Chapter 11.06: Regulations of Nitrate and Nitrite post-1920’s: the problem of residual nitrite

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


Amsterdam

January 2000

Submitted by Tristan and Lauren as Chapter 11.6 of our dad’s work on bacon.  It logically fits with the section on the preserving power of nitrites.  The review reach back to 1920 but incorporates mostly new research and developments.

INTRODUCTION

My dad worked most of his life in a pork processing plant.  He was not a scientist but he loved finding out how things work and had a special love for chemistry.  The health considerations of the use of nitrite and nitrate together in a bacon curing brine are the issue brought about by the fact that it is allowed in South Africa.  We approach the issue from the standpoint of residual nitrite from a historical perspective.  The entire matter of phenomenally complex and this is our best attempt to introduce the issue.

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SUMMARY

In South Africa commercial curing brines are still being sold that contain both nitrates and nitrites.  In Europe and America, this is not allowed.  We examine the historical context and the health concerns that gave rise to limiting residual nitrite since the 1920s and following the N-nitrosamine hysteria of the 1970s, the introduction of ascorbate or erythorbate in nitrite brines and the fact that it was made illegal to use nitrate with nitrite in certain classes of bacon.

The matter of preservatives in food is always a balancing act.  On the one hand, there is the potential negative influence on the human health of preservatives and on the other hand are the pathogens that the preservative protects us from.  It will become clear that the exact same is at issue in the consideration of nitrite.  A second important aspect is always that of dosage.  Preservatives, in high dosages, are harmful to human health, but at low dosages are less problematic.  An example is alcohol which is allowed in human food and drink even though at high dosages, it is harmful.  Nitrite falls somewhat in this category, but the reality of N-nitrosamine formation warrants a far more comprehensive approach to minimise it in bacon than only limiting the dosage of nitrite (even though this by itself is an important strategy).

Salpeter (Nitrate)

The story of bacon is the story of nitrate, nitrite and nitric oxide and its ability to preserve meat, imparting a particular cured meat flavour and a characteristic pinkish-reddish cooked-cured meat colour.

The earliest curing agent that imparted these qualities to the meat was nitrate.  The chemical formula for nitrate is CodeCogsEqn (1) .  It is used as an ingredient in gunpowder, as fertiliser and to cure meat.  It was one of the earliest and most enigmatic salts known from antiquity both in the East and the West.  There is a long line of inquiry to try and determine what gives this amazing compound its unique power.  In the West, some scholars likened it to the character of the triune God himself and in the East, in China, it was seen by some as one of the components of the elixir of immortality.

The metals most generally reacting with nitrate (CodeCogsEqn (1)) are the alkali metals, potassium to form saltpeter and sodium to form Chilian saltpeter and sometimes the alkali earth metal, calcium to form calcium nitrate, originally known as Norwegian Saltpeter.  It is most abundantly found naturally in arid regions around the world and it can be made by human action.  By the 1800s, the technology to produce it was so widespread among German farmers that authors, writing about it, did not even bother to describe the techniques used.

The preserving power of saltpeter is something which I suspect was noticed by ancient civilizations from as early as 5000 BCE.  (Salt – 7000 years of meat-curing)  There is no doubt that these civilizations also noticed its ability to cause meat colour to change from dull brown as it oxidises after slaughter, back to a reddish-pinkish colour and to impart a particular appealing cured meat taste.

It is probable that the art of meat curing developed in desert regions in China, probably in the vast Taklimakan Desert in Western China, in the Tarim Bason from where it spread into the heart of Europe.  The nations of Germany, Italy, Spain, Denmark, Holland, England, and Ireland adopted meat curing which was done with salt and a little bit of saltpeter.  In Europe, saltpeter became universal in its inclusion along with salt in meat curing between 1600 and 1750, probably near 1700.  (Lauer K., 1991)

There is evidence to suggest a link between the use of saltpeter and human disease from very early on.  Klaus Lauer (1991) analysed cookbooks from Germany and Austria between 1540 and 1900 and found some historical parallels between the use of saltpeter in foods and the appearance of colorectal cancer and multiple sclerosis.  Lauder writes,  “According to summarizing works on the history of cancer, large bowel cancer was only seldom reported in the antiquity and Middle-Ages. Its first detailed depictions date from the early 19th century, followed by a rapidly increasing number of reports during the 19th century.”  He notes that “it is of particular interest at what time nitrate or saltpeter was first used in human nutrition,” being at around the same time and increasing as the use of saltpeter in food increased.  (Lauer K., 1991)  There is, however, no record that this was ever noticed at the time.

As alarming as this is, it should be noted that this may prove nothing more than the danger of uncontrolled or highly irregular nitrite levels in meat curing brought about by the use of saltpeter.  Adding nitrate (saltpeter) is, in fact, adding nitrite.  Later we will see that the exact opposite is also true namely that adding only nitrite, is at the same time adding nitrate also since just as bacterial reduction changes nitrates to nitrites, so chemical reactions in the meat matrix change nitrites into nitrates through oxidation.  More about this later.

The people may not have noticed the health impact on the overall population of the use of nitrates, but something that was noticed is the fact that the use of saltpeter in food prevents foodborne toxins.  Kerner in Germany found in a series of studies conducted in 1817, 1820 and 1822 that the outbreaks of sausage poisoning or botulism are linked to the omission of nitrate (saltpeter) in the salt mixture to cure meat for sausage production.    Botulism is an often fatal foodborne disease from the toxins produced by bacteria, Clostridium Botulinum. (Frences, M. P., et al. 1981)

In a time of superstition and secret remedies, saltpeter was regarded with awe and wonder.  (Saltpeter:  A Concise History and the Discovery of Dr. Ed Polenske)  A newspaper report from 1898 says that saltpeter miners working in a cave have “remarkable health.”  (The Wyandotte Herald, Kansa City, Kansas, 7 April 1898, “Air in Mammoth Cave“)

So, despite the fact that we can look back at the time before 1920, and see that there may have been an impact from the increased use of saltpeter on the general health of the German and Austrian population, and by extension, on the European population, such a link was probably not obvious.  The general view of saltpeter was favourable.

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Nitrite

From the late 1800s, scientists started to work out that the saltpeter was not the real curing agent, but its cousin, the far more toxic compound, nitrite (CodeCogsEqn (2)). It started to emerge that it has a more direct impact on curing than nitrate.  

Contrary to the generally positive view of saltpeter pre-1900’s, nitrite was viewed by the public in the most negative light.  Their view was not completely unfounded because it is estimated that nitrite is 10 times more toxic than nitrate, but what the general public did not understand was that nitrate became nitrite after a time and that the nitrate from their darling of all salts, sodium or potassium nitrate, turned into the villain, nitrite.

Scientists experimented from early on in its direct use in meat curing.  A private laboratory in Germany, founded in 1848 by C.R. Fresenius recorded, for example, experimented with sodium nitrite as curing agent.  (Concerning Chemical Synthesis and Food Additives)  THis is the earliest experiment I have been able to locate thus far where nitrite is used as a preservative in meat.

The Russian botanist and microbiologist, Sergei Nikolaievich Winogradsky (1856 – 1953) identified a class of bacteria which oxidizes ammonia (CodeCogsEqn (3).gif) or ammonium (CodeCogsEqn (4)) to nitrite (CodeCogsEqn (2)) and nitrite to nitrate (CodeCogsEqn (1)).  The process is called nitrification.

E. Meusel (1875) discovered another class of microorganisms living in soil and natural waters which reduce nitrates to nitrites and even further.  (Meusel, E. 1875)  It was found that in the absence of oxygen, these microbes use and thus reduces nitrates (CodeCogsEqn (1)) to nitrite (CodeCogsEqn (2)) in their metabolic processes.  In 1790 Antoine de Lavoisier (1743 – 1794) named the compound nitrite “as they are formed by nitric or by nitrous acid.”  (Lavoisier, A; 1965: 217)  Thus two different compounds exist with only a small change in the spelling namely nitrate and nitrite, indicating the fact that nitrite has one less oxygen atom compared to nitrate.  The loss of one oxygen atom, however, renders the molecule far more reactive, increasing its toxicity 10 times.

In 1891, Eduard Polenske, working for the Imperial Health Office, analysed cured meat for its nutritional value and noted that the nitrate in the curing brine and in the meat changed to nitrites.  He predictably and correctly speculated that this was due to microbial activity, identified by Meusel, 16 years earlier.  In his article, he predicted that the expected reduction would cause an outcry.

Academic work continued uncovering a much closer relationship between the toxic nitrite and meat curing than the darling of the sciences, saltpeter.  The German scientist, Nothwang confirmed the presence of nitrite in curing brines in 1892.  In 1899, another German scientist, K. B. Lehmann confirmed that the cured colour was linked to nitrite and not saltpeter.  Yet another German hygienists, one of Lehmann’s assistant at the Institute of Hygiene in Würzburg,  Karl Kißkalt (1875 – 1962), confirmed Lehmann’s observations and showed that the same red colour resulted if the meat was left in saltpeter (potassium nitrate) for several days before it was cooked, thus confirming Polenske’s notion of bacterial reduction of nitrate to nitrite which finally cures the meat.  S. J. Haldane showed that nitrite is further reduced to nitric oxide (NO) in the presence of muscle myoglobin and forms iron-nitrosyl-myoglobin. It is nitrosylated myoglobin that gives cured meat, including bacon and hot dogs, their distinctive red colour and protects the meat from oxidation and spoiling.

The work of these scientists was enough evidence for the German government and in 1909, probably due to the negative views of the public towards nitrite, they legalised only the use of a partially reduced form of nitrates in curing mixes which were marketed across Europe.  (Bryan, N. S. et al, 2017: 86 – 90)

The Irish invention

The Irish and later the Danes and the English applied their knowledge of bacterial reduction of nitrate to nitrite and developed a curing method where they reused brine that was “reduced” to nitrite already. They allowed fresh brine to be continually introduced into the system, bacterial reduction to take place and thus supplemented the nitrite concentration of the previously used brine.  This had the additional benefit of “seeding” new brine with just the right bacteria required for nitrite reduction.

According to this method they first injected fresh brine consisting of salt and saltpeter (potassium nitrate) into meat.  They then left the meat for several days in a cover brine. The cover brine was never changed and came to be known as the “mother brine.”  It was their source of nitrite that was directly applied to the curing process.  The mother brine was strained and boiled before it was re-used to eliminate pathogenic bacteria.

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The German/ Austro-Hungarian Invention

Where Ireland, Denmark and England focused on harnessing the power of old brine, in Germany they were toying with the idea of using sodium nitrite as their source of nitrite.  Sodium nitrite was at this time used extensively in an intermediary step in the lucrative coal tar dye industry that flourished in Germany and in the Austrian-Hungarian empire, notably around the city of Prague.  There was a second use of sodium nitrite in medicine. It was expensive to produce and viewed with much skepticism by the general public for use in food on account of its high toxicity.  (Concerning the direct addition of nitrite to curing brine)

It was the First World War that provided the transition events that caused the sodium nitrite to end up being used as the source of nitrite in curing brines in Germany where its use in food was still illegal.  Saltpeter was reserved for the war effort is one of the main components used in the manufacturing of gunpowder and was consequently no longer available as curing agent for meat during World War One. (Concerning the direct addition of nitrite to curing brine)

1914

In August 1914, the War Raw Materials Department (Kriegsrohstoffabteilung or KRA) was set up under the leadership of Walther Rathenau.  It was Rathenau who was directly responsible for the prohibition on the use of salpeter.  He, therefore, is the person in large part responsible creating the motivation for the meat industry in Germany to change from saltpeter to sodium nitrite as curing medium of choice for the German meat industry during World War One.  (Concerning the direct addition of nitrite to curing brine)

The first country to legalise the use of nitrite directly was the Austro-Hungarian Empire and in 1915.  At age 19, Ladislav Nachmüllner invents Praganda, the first legal commercial curing brine containing sodium nitrite in the city of Prague.  He says that he discovered the power of sodium nitrite through  “modern-day professional and scientific investigation.”  He probably actively sought an application of the work of Haldane. He quotes the exact discovery that Haldane was credited for in 1901 that nitrite interacts with the meat’s “haemoglobin, which changes to red nitro-oxy-haemoglobin.”  (The Naming of Prague Salt)

1917

By 1917 nitrite was not only used for curing meat in Germany, but proprietary meat cures containing nitrites were being marketed across Europe.  (Concerning Chemical Synthesis and Food Additives)

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Developments in the United States

Both these methods were being looked at very closely in the United States around this time.

1905

The first recorded direct use of sodium nitrite as a curing agent in the USA was in a secret experiment in 1905.  The USDA approved its use as a food additive in 1906.  (Concerning the direct addition of nitrite to curing brine)

1910

A court case was brought by the US Federal Government against the Mill and Elevator Company of Lexington, Nebraska.  The charge was that they adulterated and misbranded flour and sold it to a grocer in Castle, Missouri.  The case was brought by the government under the pure food and drug act of 1906.  (Chicago Daily Tribune ; 7 July 1910; Page 15) The government contended that “poisonous nitrites are produced in the flour by bleaching.”  This is one example of the gigantic controversy that raged around the world about the use of nitrites in food and the careful work that was done by the US government in the 1920, 30’s and onwards, was in the first place in dealing with the known high toxicity of nitrites.

1915

In 1915, George F. Doran of Omaha, Nebraska, filed a patent for using “sterilized waste pickling liquor which he discovered contains soluble nitrites produced by conversion of the potassium nitrate, sodium nitrate, or other nitrate of the pickling liquor when fresh, into nitrites.  As such his patent involved taking waste pickling liquor from the cured meats.”  This is the same concept as tank curing invented in Denmark sometime before 1910 and probably after 1899. He states the objective of his invention as “to produce in a convenient and more rapid manner a complete cure of packing house meats; to increase the efficiency of the meat-curing art; to produce a milder cure; and to produce a better product from a physiological standpoint.” (US 1259376 A)

Despite the obvious advantage of a far quicker curing time of the use of sodium nitrite had over the tank cured Irish/ Danish/ English method, the fact that Doran still took the trouble to register the patent for a tank curing method in 1915 makes sense if one considers that tank-curing or the Wiltshire curing process became widespread in application in England.

The problem with the Irish/ Danish and later, Engish system was, of course, shelf life due to the high microbial load from the mother brine and the uncontrolled nature of the process of nitrite formation (nitrite levels have been shown to range between 2 and 960 ppm in products cured using this method). (Bryan, N. S. et al, 2017: 86 – 90)

1923

In 1923, the Bureau of Animal Industry commissioned a study to investigate the direct addition of nitrite for meat curing.  Kerr, et al, under the supervision of inspectors from the Bureau of Animal Industry, cured hams with approximately 2000 ppm nitrite in the curing mix.  The first issue they investigated was to compare nitrite curing with nitrate curing from the standpoint of organoleptic equivalence and if excess amounts of nitrite are required for nitrite curing.

They also looked at the amount of nitrite that was left in the meat after sufficient curing took place, thus introducing the concept of residual nitrite.  These they compared with the amount of nitrite that was in the curing brine.  The question was how much nitrite is required to cure meat.  It was known that nitrite is a more powerful toxin than nitrate; it was further known that using nitrate instead of nitrite caused inconsistent nitrite levels in the curing brine and in the meat.  By understanding the amount of nitrites that typically react in the meat to form nitric oxide and to cure the meat and by taking that as the limit of nitrite that can be added directly, one, therefore, minimises the risk of having consumers ingest nitrites.

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1925

By 1925 a document was prepared by the Chicago based organisation, The Institute of American Meat Packers and published in December of this year.  The Institute started as an alignment of the meatpacking companies set up by Phil Armour, Gustavus Swift, Nelson Morris, Michael Cudahy, Jacob Dold and others with the University of Chicago.  (Concerning the direct addition of nitrite to curing brine)

A newspaper article about the Institute sets its goal, apart from educating meat industry professionals and new recruits, “to find out how to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.”   (The Indiana Gazette.  28 March 1924).  In this statement is the clue to the reason for its dominance in the United States where bigger, better and faster was the call to arms for the new world’s industries.

The document is entitled, “Use of Sodium Nitrite in Curing Meats“, and it is clear that the direct use of nitrites in curing brines has been practiced from earlier than 1925. (Industrial and Engineering Chemistry, December 1925: 1243)

The article begins “The authorization of the use of sodium nitrite in curing meat by the Bureau of Animal Industry on October 19, 1925, through Amendment 4 to B. A. I. Order 211 (revised), gives increased interest to past and current work on the subject.”  Sodium Nitrite curing brines would, therefore, have arrived in the USA, well before 1925.

The rest of the opening paragraph continues to elaborate on the reason for its preference.   “It is now generally accepted that the saltpeter added in curing meat must first be reduced to nitrite, probably by bacteria, before becoming available as an agent in producing the desirable red color in the cured product.  This reduction is the first step in the ultimate formation of nitrosohemoglobin, the color principle.  The change of nitrate to nitrite is by no means complete and varies within considerable limits under operating conditions.  Accordingly, the elimination of this step by the direct addition of smaller amounts of nitrite means the use of less agent and a more exact control.”

1926

The 1926 study by Kerr and co-workers, was done long before there was any link established between nitrite and the formation of cancer-causing substances upon frying and ingestion.  This only emerged in the ’70s.  In 1926, the work was based on the general knowledge of nitrite’s toxicity and the publics’ very negative perceptions about it.  In the report, they state that public health was the primary motivation behind the study.  (Kerr, et al, 1926: 543)  The test was a step in the right direction – towards defining and limiting residual nitrite.

I quote from their report.  “The first experiment involving the direct use of nitrite was formally authorized January 19, 1923, as a result of an application by one of the large establishments operating under Federal meat inspection. Before that time other requests for permission to experiment with nitrite had been received but had not been granted. The authorization for the first experiment specified that the whole process was to be conducted under the supervision of bureau inspectors and that after the curing had been completed the meat was to be held subject to laboratory examination and final judgment and would be destroyed if found to contain an excessive quantity of nitrites or if in any way it was unwholesome or unfit for food. This principle was rigidly adhered to throughout the experimental period, no meat being passed for food until its freedom from excessive nitrites had been assured, either by laboratory examination or through definite knowledge from previous examinations, that the amount of nitrite used in the process would not lead to the presence of an excessive quantity of nitrites in the meat. By “excessive^ is meant a quantity of nitrite materially in excess of that which may be expected to be present in similar meats cured by the usual process.”  (Kerr, et al, 1926: 543)

An interesting side note is the fact that this fixes the date of the first official experiment using nitrites ever conducted in the United States.  There can be little doubt that the large packing plants in Chicago used nitrites directly in meat curing, long before this, at least from 1918, following World War 1.  I have even received reports of the first unofficial experiment of this nature that was done in 1905, presumably also in Chicago.  (Concerning the direct addition of nitrite to curing brine)  The large establishment who applied for the permit would have been one of the following lists of packers, the Armour Packing operation, Morris & Company, Cudahy Packing Company, Wilson Packing Plant or Swift Packing.  These four companies, at the time, were some of the largest and most powerful corporations on earth.

The maximum nitrite content of any part of any nitrite-cured ham [was found to be] 200 parts per million. The hams cured with nitrate in the parallel experiment showed a maximum nitrite content of 45 parts per million.”  (Kerr, et al, 1926: 543) The conclusion was that “hams and bacon could be successfully cured with sodium nitrite, and that nitrite curing need not involve the presence of as large quantities of nitrite in the product as sometimes are found in nitrate- cured meats.”  (Kerr, et al, 1926: 545)

Related to health concerns, the report concluded the following:

  1. The presence of nitrites in cured meats was already sanctioned by the authoritative interpretation of the meat inspection and pure food and drugs acts sanctioning the use of saltpeter; as shown previously, meats cured with saltpeter and sodium nitrate regularly contain nitrites. (Wiley, H, et al, 1907) (Kerr, et al, 1926: 550)
  2. The residual nitrites found in the nitrite-cured meats were less than are commonly present in nitrate-cured meats.  The maximum quantity of nitrite found in nitrite-cured meats, in particular, was much smaller than the maximum resulting from the use of nitrate.  (Kerr, et al, 1926: 550)
  3. The nitrite-cured meats were also free from the residual nitrate which is commonly present in nitrate-cured meats.  (Kerr, et al, 1926: 550)
  4. On the contrary, the more accurate control of the amount of “nitrite and the elimination of the residual or unconverted nitrate are definite advantages attained by the substitution.  (Kerr, et al, 1926: 550)

Following further studies, the Bureau set the legal limit for nitrites in finished products at 200 parts per million.  (Bryan, N. S. et al, 2017: 86 – 90)

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Conventional wisdom that surfaced in the 1920s suggested that nitrate and nitrate should continue to be used in combination in curing brines  (Davidson, M. P. et al; 2005:  171) as was the case with the Danish curing method and the mother brine concept of the previous century.  Nitrite gives the immediate quick cure and nitrate acts as a reservoir for future nitrite and therefore prolongs the supply of nitrite and ensures a longer curing action.  This concept remained with the curing industry until the matter of N-nitrosamines came up in the 1960s and ’70s, but remarkably enough, it still persists in places like South Africa where to this day, using the two in combination is allowed for bacon.

1931

The USDA progressed the ruling on nitrate and nitrites further in 1931 by stating that where both nitrites and nitrates are used, the limit for nitrite is 156 ppm nitrite and 1716 nitrate per 100lb of pumped, cured meat.  (Bryan, N. S. et al, 2017: 86 – 90)

1960’s – N-Nitrosamine

Up to the 1960’s the limit on the ingoing level of nitrites was based on its toxicity.  In the late 1950s an incident occurred in Norway involving fish meal that would become a health scare rivaled by few in the past.  1960’s researchers noticed that domestic animals fed on a fodder containing fish meal prepared from nitrite preserved herring were dying from liver failure.  Researchers identified a group of compounds called nitrosamines formed by a chemical reaction between the naturally occurring amines in the fish and sodium nitrite.  Nitrosamines are potent cancer-causing agents and their potential presence in human foods became an immediate worry.  An examination of a wide variety of foods treated with nitrites revealed that nitrosamines could indeed form under certain conditions.  Fried bacon, especially when “done to a crisp,” consistently showed the presence of these compounds.  (Schwarcz, J)  In bacon, the issue is not nitrates, but the nitrites which form N-nitrosamines.

This fundamentally sharpened the focus of the work of Kerr and co-workers of the 1920s in response to the general toxicity of nitrites to the specific issue of N-nitrosamine formation.  Reviews from 1986 and 1991 reported that “90% of the more than 300 N-nitroso compounds that have been tested in animal species including higher primates causes cancer, but no known case of human cancer has ever been shown to result from exposure to N-nitroso compounds.”  However, despite this, there is an overwhelming body of indirect evidence that shows that a link exists and “the presence of N-nitroso compounds in food is regarded as an etiological risk factor.   It has been suggested that 35% of all cancers in humans are dietary related and this fact should not surprise us.  (Pegg and Shahidi, 2000)

Studies have been done showing that children who eat more than 12 nitrite-cured hot dogs per month have an increased risk of developing childhood leukemia.  The scientists responsible for the findings themselves cautioned that their findings are preliminary and that much more studies must be done.  It may nevertheless be a good approach for parents to reduce their own intake of such products along with that of their children in cases where intake is high.  (Pegg and Shahidi, 2000)

These studies must be balanced by the fact that an overwhelming amount of data has been emerging since the 1980s that indicate that N-nitroso compounds are formed in the human body.  What is important is that we keep on doing further research on N-nitrosamines and the possible link to cancer in humans.  Not enough evidence exists to draw final conclusions.

1970 – The Response to the N-Nitrosamine Scare

Back to the 1970s, so grave was the concern of the US Government about the issue that in the early 1970s they seriously considered a total ban on the use of nitrites in foods. (Pegg and Sahidi, 2000)  The response to the N-nitrosamine issue was to go back to the approach that was implemented following the work of Kerr and co-workers in 1926.

The first response was to eliminate nitrate from almost all curing applications.  The reason for this is to ensure greater control over the curing.  Meat processors continued to use nitrate in their curing brines after 1920 until the 1970s.  One survey from 1930 reported that 54% of curers in the US still used nitrate in their curing operations.  17% used sodium nitrite and 30% used a combination of nitrate and nitrite.  By 1970, 50% of meat processors still used nitrate in canned, shelf-stable.  In 1974 all processors surveyed discontinued the use of nitrates in these products including in bacon, hams, canned sterile meats, and frankfurters.  One of the reasons given for this change is the concern that nitrate is a precursor for N-nitrosamine formation during processing and after consumption.  (Bryan, N. S. et al, 2017: 86 – 90)

The reason for the omission in bacon, in particular, is exactly the fact that the nitrates will, over time continue to be converted to nitrites which will result in continued higher levels of residual nitrites in the bacon compared to if only nitrite is used.  The N-nitrosamine formation from nitrites is a reaction that can happen in the bacon during frying or in the stomach after it has been ingested.  It will not happen from the more stable nitrates.

It has been discovered that nitrate continues to be present in cured meats.  Just as the view that if nitrate was added, no nitrite is present in the brine as was the thinking in the time before the early and mid-1800s, in exactly the same way it is wrong to think that by adding nitrite only to meat, that no nitrate is present.  “Moller (1971) found that approximately 20% of the nitrite added to a beef product was converted to nitrate within 2 hours of processing.  Nitrate formation was noted during incubation before thermal processing, whereas after cooking only slight nitrate formation was detected.  Upon storage, the conversion of nitrite to nitrate continued.  Herring (1973) found a conspicuous level of nitrate in bacon formulated only from nitrite.  As greater concentrations of nitrite were added to the belly, a higher content of nitrate was detected in the finished product.  They reported that 30% of the nitrite added to bacon was converted to nitrate in less than one week and the level of nitrate continued to increase to approximately 40% of the added nitrite until about 10 weeks of storage.  Moller (1974) suggested that when nitrite is added to meat, a simultaneous oxidation of nitrite to nitrate and the ferrous ion of CodeCogsEqn (5)  to the ferric ion of metMb occurs.” Adding ascorbate or erythorbate plays a key role in this conversion.  (Pegg and Shahidi, 2000)  The issue is not the nitrate itself, but the uncontrolled curing that results from nitrate and the higher residual nitrites.

Secondly, the levels of ingoing nitrite were reduced, especially for bacon.  The efficacy of these measures stems from the fact that the rate of N-nitrosamine formation depends on the square of the concentration of residual nitrites in meats and by reducing the ingoing nitrite, the residual nitrite is automatically reduced and therefore the amount of N-nitrosamines.  (Pegg and Sahidi, 2000)  Legal limits were updated in 1970 in response to the nitrosamine paranoia.  A problem with this approach is however that no matter by how much the ingoing nitrite is reduced, the precursors of N-Nitrosamine still remain in the meat being nitrites, amines, and amino acids.

An N-nitrosamine blocking agent was introduced in the form of sodium ascorbate or erythorbate. “There are several scavengers of nitrite which aid in suppressing N-nitrosation; ascorbic acid, sodium ascorbate, and erythorbate have been the preferred compound to date.  Ascorbic acid inhibits N-Nitrosamine formation by reducing CodeCogsEqn (11)  to give dehydroascorbic acid and NO.  Because ascorbic acid competes with amines forCodeCogsEqn (11), N-Nitrosamine formation is reduced.  Ascorbate reacts with nitrite 240 times more rapidly than ascorbic acid and is, therefore, the preferred candidate of the two.  (Pegg and Sahidi, 2000)

More detailed studies identified the following factors to influence the level of N-nitrosamine formation in cured meats.  Residual and ingoing nitrite levels, preprocessing procedure and conditions, smoking, method of cooking, temperature and time, lean-to-adipose tissue ratio and the presence of catalyst and/ or inhibitors.  It must be noted that in general, levels of N-nitrosamines formation has been minuscule small, in the billions of parts per million and sporadic.  The one recurring problem item remained fried bacon.  In its raw state bacon is generally free from N-nitrosamines “but after high-heat frying, N-nitrosamines are found almost invariably.”  One report found that “all fried bacon samples and cooked-out bacon fats analyzed” were positive for N-nitrosamines although at reduced levels from earlier studies.  (Pegg and Sahidi, 2000)

Regulatory efforts since 1920 have shown a marked decrease in the level of N-nitrosamines in cured meats, even though it is still not possible to eliminate it completely.  “Cassens (1995) reported a marked decrease (approx 80%) in residual nitrite levels in of US prepared cured meat products from those determined 20 years earlier; levels in current retail products were 7 mg/kg from bacon.”  This and similar results have been attributed to lower nitrite addition levels and the increased use of ascorbate or erythorbate.  (Pegg and Sahidi, 2000)

Current USA Regulations and Tightening the Measures from the 1970s

Nitrite can be used in foods and nitrate, very selectively based on the product category and the method of curing.  Immersion cured, massaged or pumped products (example hams or pastrami) – maximum ingoing level of 200 ppm sodium or potassium nitrite and/ or 700 ppm nitrate based on raw product weight.  (Bryan, N. S. et al, 2017: 86 – 90)

Dry-cured products – a maximum of 625 ppm ingoing nitrite, and/ or 2187 ppm nitrate since the products have long curing times that result in immediate nitrite reaction with myoglobin and longer-term conversion of nitrate to nitrite.  (Bryan, N. S. et al, 2017: 86 – 90)

Comminuted products such as Frankfurters, Bologna, and other cured sausages – maximum ingoing nitrite level of 156 ppm sodium or potassium nitrite based on raw meat block.  Nitrite can be added to all these at a rate of 1718 ppm regardless of salt used.  (Bryan, N. S. et al, 2017: 86 – 90)

1978 Bacon Levels – USA

Ingoing nitrite levels were reduced in 1978 and a required limit was set for ascorbate.  It was also explicitly ruled that nitrate may not be used in bacon production.

-Maximum ingoing level of sodium nitrite – 120 ppm

-Maximum ingoing level of potassium nitrite – 148 ppm

-547 ppm ascorbate or erythorbate must be added.

(Bryan, N. S. et al, 2017: 86 – 90)

1980

In the USA, in 1980, the National Acadamy of Sciences (NSA) entered into a contract with the USDA and FDA.  They established the Committee on Nitrate and Alternative Curing Agents in Food.  The brief of the committee was to investigate the health risk associated with the overall exposure to nitrate, nitrite and N-nitroso compounds.  They published a report, “The Health Effects of Nitrite and N-nitroso Compounds.”

They found nitrate not to be carcinogenic or mutagenic.  It was found that certain populations showed an association of exposure to high nitrate levels and certain cancers.  More studies are required.

Nitrite was similarly found not to act directly as a carcinogen in animal studies and more studies are necessary.

The committee recognised the use of nitrite as an effective barrier against foodborne botulism, thus validating the continued use of nitrites in meat curing.  They also put the overall risk in perspective by estimating the lifetime risk of cancer from cured meats to be one in a million if “humans were exposed to a daily dose of 5.8 to 19 ng of nitrosodimethylamine per ki~ogram of body weight or 0.85 to 2. 7 ng of nitrosodimet~lamine per em of body surface. In arriving at this estimate, the committee has also assumed that (1) the dietary doses given to rats can be converted to unit of dose per unit of body weight or per unit of body surface area to reflect human exposure and (2) that nitrosodimethylamine is the main source of exposure to nitrosamine& for humans and is, therefore, representative of all nitrosamine&, even though its potency in animals is greater than that of many other nitrosamine.”

The committee also examined seven pothetical population groups and estimated that the lifetime risk of cancer from exposure to all sources of nitrosamines would be 820 to 18,000 per million for a high risk group (including occupational exposure), 11 to 250 in a million for a high cured meat diet group, 8 to 180 in a million for an average population of nonsmokers, and 3 to 74 in a million for a low risk group.”

A specific recommendation, relevant to the question of the use of nitrates in curing brines is that the use of nitrates in curing systems should be eliminated with the exception of products where long curing time is required.  The reason is that nitrate and nitrates can have acute toxic effects and contribute to the formation of N-nitrose compounds.

Despite all this, the committee found that the prudent approach is to continue to use nitrite as a proven and effective hurdle to prevent the outgrowth of Clostridium Botulinum spores and the accompanying toxin formation.  It is in the public interest to assume that temperature and other product abuses will take place and using nitrite as a hurdle remains a reasonable measure.

Here is the pdf copy of the entire report:  The Health Effects of Nitrite and N-nitroso Compounds

rn 7

New 1986 Bacon Levels – USA – Testing the Limits of the System

The general trend of reducing residual nitrate and limiting N-nitrosamine formation continued.  The danger, however, exists that ingoing nitrite levels may be reduced so dramatically as to compromise its function as a barrier against botulism.  The danger of nitrites and its benefits must always be held in balance.

-Skinless bacon – the requirements were kept at the 1978 levels, but it was explicitly emphasised that these ruling applies in order to reduce the possibility of N-nitrosamine formation.  A practical measure was introduced which allows for an approximately 20% variance is allowed from the ingoing nitrite on injection or massaging (96-144 ppm).

In order to ensure efficacy against pathogens, sodium nitrite can be reduced to 100 ppm (123 ppm potassium nitrite) with an “appropriate partial quality control program.”  If sugar and a starter culture are added to the brine, 40 – 80 ppm sodium nitrite (49 – 99 potassium nitrite).

Dry-cured bacon – the limit was set at 200 ppm nitrite or 246 potassium nitrite.

(Bryan, N. S. et al, 2017: 86 – 90)

EU Rules, Directive 95/2/EC, Modified in Directive 2006/52/EC

Maximum ingoing level of bacon is 150 ppm nitrite; max residue level at between 50 and 175 ppm. (in Denmark, this limit is lower at 60 – 150 ppm for semi preserved products and special cured hams).  (Bryan, N. S. et al, 2017: 86 – 90)

Canadian Regulations Bacon

120 ppm and it is stated that this level is set in order to prevent N-Nitrosamine formation.  (Bryan, N. S. et al, 2017: 86 – 90)

South African Regulations

The South African max allowed limits on nitrite, nitrate, and ascorbate or erythorbate are:

from Regulation R965 of 1977(18):

– Potassium and sodium nitrate:  200mg/ kg
– Potassium or sodium nitrite: 160mg/kg

Where nitrate and nitrite are used in combination they must be added together and proportionally neither one can exceed the max limit (section 2b of Regulation R965 of 1977).

For using erythrobic acid or sodium erythorbate:  550 mg/kg
L Ascorbic Acid:  550 mg/kg.

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CONCLUSION

The continued use of nitrite is undoubtedly valid in the face of its efficacy against serious foodborne pathogens.  It is, however, important to take every precaution possible to mitigate the risk posed by N-nitrosamines, including limiting the maximum allowed addition of nitrite to curing brines, limiting residual nitrite, controlling the curing by using nitrites and not nitrates in bacon and the addition of correct levels of ascorbate or erythorbate.  The fact that nitrates are still allowed with nitrites in curing brines in South Africa is a matter of concern.

Objections are two-fold.  On the one hand, it increases the residual nitrites (over time, nitrites continue to be formed from nitrates through bacterial reduction) increasing the amount of nitrites present during frying and ingested which can form N-nitrosamines in the stomach.  Another issue is that the exact dosage of nitrites is not left, in part, to the action of bacteria and I fail to see the point behind this.  The thinking about nitrates acting as a reservoir for continued nitrite production in order to maximise its antimicrobial efficacy becomes an irrelevant point in light of the danger of N-nitrosamine formation from the higher residual nitrites and the thinking which stems from the 1920s has been altered around the world with good reason and yielding good results.

An equally serious problem may be that the South African regulations do not make the use of ascorbate or erythorbate mandatory nor does it set minimum required levels.  It will be interesting to do a study of the residual nitrate levels in South African bacon over time.  Much work remains.

After we did the article, it occurred to us that if we would cut out cured meat from our diet altogether in order to prevent even the smallest chance of exposure to N-nitrosamines and if we would subject the rest of my diet to the same rigor applied to the issue of nitrites, it may very well be found that we were better off eating the processed foods in comparison with what we may consume in its place.  As a whole, it is possible that consuming processed foods along with regular exercises places me in a better position health-wise than cutting out these foods from my diet altogether and no exercise.  This issue must be seen in context.  This is a fact that researchers regularly point to when they publish data on the health effects of nitrite.  I can only echo the prevailing sentiment on the subject – that much more research needs to be done.

Few issues received more comprehensive treatment than the matter of N-nitrosamine formation since the early ’70s and an unfathomable amount of excellent literature exists on the subject.  I write these articles in order to learn.  As the issue of meat curing itself, the matter at hand is very complex.


Further Reading

Regulations of Nitrate and Nitrite post-1920’s: the problem of residual nitrite.


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References

Bryan, N. S. and Loscalzo, J. (Editors) 2017.  Nitrite and Nitrate in Human Health and Disease.  Springer International Publishing.  Chapter by J. T. Keeton.  jkeeton@tamu.edu

Chicago Daily Tribune, 7 Jul 1910, Thu. P15

Frances, M. P. (Editor) et al..  1981.  The Health Effects of Nitrate, Nitrite, and N- Nitroso Compounds.  National Academic Press. (https://books.google.co.za/books?id=QkorAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false)

The Indiana Gazette, 28 March 1924

KERR, R. H., MARSH, C. T. N., SCHROEDER, W. F., and BOYER, E. A..  1926.   Associate Chemists, Bureau of Animal Industry, United States Department of Agriculture.  THE USE OF SODIUM NITRITE IN THE CURING OF MEAT.  Journal of Agricultural Research Vol. 33, No. 6.  Sept. 15, 1926 Key No. A-112.  Washington, D. C.

Lauer K. 1991.  The history of nitrite in human nutrition: a contribution from German cookery books.  Journal of clinical epidemiology. 1991;44(3):261-4.

Lavoisier, A.  1965.  Elements of Chemistry.  Dover Publications, Inc.  A republication of a 1790 publication

Morton, I. D. and Lenges. J.  1992.  Education and Training in Food Science: A Changing Scene.  Ellis Hornwood Limited.

Schwarcz, J http://blogs.mcgill.ca/oss/2013/01/04/what-is-saltpeter-used-for-and-is-it-true-it-reduces-certain-%E2%80%9Ccarnal-urges%E2%80%9D/

WILEY, H. W., DUNLAP, F. L., and MCCABE, G. P. 1907. DYES, CHEMICALS, AND PRESERVATIVES IN FOODS. U. S. Dept. Agr., Off. Sec. Food Insp. Decis. 76, 13 p.

The Wyandott Herald, Kansa City, Kansas, 7 April 1898, “Air in Mammoth Cave

http://www.elmswell-history.org.uk/arch/firms/baconfactory/baconfactory.html

https://www.theguardian.com/lifeandstyle/wordofmouth/2011/may/11/how-to-make-bresaola

Chapter 11.05: The Preserving Power of Nitrite

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


The Preserving Power of Nitrite

October 1959

Dear Lauren,

Star_Tribune_Tue__Dec_29__1959_
From Star Tribune, Minneapolis, Minnesota, 25 December 1959.

It is almost Christmas and I am looking forward to your visit!  There is a possibility that Trista will be here also.  You can imagine my great excitement!

I am sure you read the news of the international opposition to the policies of the South African government. I am very happy about this for the policies of the National Party are diabolical and nothing but a perpetuation of the suppression of the black man since the day Europeans set foot on this great continent.  I include a newspaper clipping from a newspaper from Minnesota. The government is set on creating independence from Brittain where the opposition to the Apartheid policies is gaining momentum.  I am sure they will succeed because the National Party is very determined.

The white people live under the wrong assumption that they need laws to secure their future.  They desire to preserve their heritage of this land by oppressing others.  This can never to the basis for survival of a nation.  I am glad that Oscar and I decided years ago to seek independence through economic means and not political.  I often wondered if we would have been able to start our bacon company if we were black.

My goal is not to judge every small part of history but to report the story as it unfolded.  I wrote to Tristan how it happened that the direct addition of sodium nitrite in curing brines replaced tank curing as the most advanced way of curing bacon.  The question revolved around the fact that nitrite, in too high dosages is toxic.  Thinking very simplistically about it, the fact that it is toxic is not only something to be very conscious of but also contributes massively to its usefulness in bacon curing.  It means that we place a substance, toxic to microorganisms in the very small dosages we add in brine, inside the meat and we coat the bacon from the outside with smoke, another toxin for microorganisms that protects the meat from the outside.  The important point is that in the small dosages we use, it is not harmful to humans.

Preservation Through the Right Brine Composition

Conventional wisdom that surfaced in the 1920s suggested that nitrate and nitrate should continue to be used in combination in curing brines  (Davidson, M. P. et al; 2005:  171) as was the case with the Danish curing method and the mother brine concept of the previous century.  Nitrite gives the immediate quick cure and nitrate acts as a reservoir for future nitrite and therefore prolongs the supply of nitrite and ensures a longer curing action.  The question comes up if there are any other reasons why one should continue to use nitrate?  Is there, for example, any preservative role of nitrate and while we are considering this question, what exactly is the preservative value of nitrite?

Clostridium Botulinum – the Key Organism

The first thing to remember when considering the effectiveness of a preservative is that not all preservatives are equally effective against all microorganisms.  A second point is that different microorganisms are generally associated with different kinds of food.  When we look at bacon in particular, what are some of the microorganisms associated with it?   Some of the these are Lactobacillus, Pseudomonas, Clostridium, yeasts like Dabaryomyces and molds like Aspergillus and Penicillium. (Jay, J. M. et al.; 2005:  102)  We then want to look at antimicrobials that are particularly effective against these and other organisms associated with bacon.

Before we look at this list more carefully and how these organisms are managed, one organism is the starting point when considering the antimicrobial efficacy of any chemical.  The first and most important microorganism, to begin with, associated with bacon and other foods is clostridium botulinum.  (see Concerning Clostridium Botulinum – the priority organism)

The reason for its priority in food safety is that certain types of toxins counts as some of the most lethal substances on earth.Montclair_Tribune_Thu__Apr_20__1972_

A headline appeared in a newspaper in California in 1972, reporting that nitrate has been found effective against botulism.  (Montclair Tribune; 20 April 1972:  28)  The headline incorrectly read “Nitrate useful against botulism“.  The study is reporting on deals with nitrite.

The discovery was newsworthy.  Botulism is a serious and potentially fatal disease that caused considerable alarm since it was identified in the early 1800s by Justinus Kerner.  (Emmeluth, D.; 2010: 16)  It is caused by a toxin called botulin, a neurotoxic protein produced by the bacteria clostridium botulinum.  It is so poisonous that one-millionth of a gram can kill an adult human.  500mL is enough to kill every person on earth.  (Sterba, J. P.; 28 April 1982)

Preventing it remained a focus for the food industry throughout the 1900s and into the present day and any consideration of the anti-microbial effect of nitrate and nitrite must include its effectiveness in preventing it.  It affects humans and animals and one of the ways we contract it is through food.

Clostridium botulinum was isolated as the microorganism causing botulism in 1895 by Emile Emergem, professor of bacteriology at the University of Ghent, in Belgium.  (Emmeluth, D.; 2010: 19)  The following year and article appeared in The Centralia Enterprise and Tribune in Centralia, Wisconsin, reporting on a warning issued by the Connecticut State Department of Health, issued in its weekly bulletin, in response to two cases of botulism that occurred in New Haven, the week prior.  The warning identified home canned foods as the usual source of botulism.  Especially “improperly processed, non-acid fruits and vegetables which are served cold”.  The incidents of the previous week were traced back to improperly processed home-canned figs.   (The Centralia Enterprise and Tribune; 25 January 1896:  5)

Such was the public’s concern over botulism that in 1896 when in the US new Food and Drug Administration rules came into effect allowing low-level radiation of food, concern was raised by some consumer groups that this would destroy “more common and more vulnerable spoilage bacteria” while deadly botulism bacteria would grow undetected.  The argument was that the more common spoilage bacteria would alert the consumer that the food has gone bad before the deadly botulism toxins could be produced.  The FDA responded to this concern by pointing out that at higher radiation levels it would share the concern, but that the levels were to low to completely destroy the spoilage bacteria.  (The Laredo Times;  1 December 1896: 14)

It is interesting that this same principle is still a recognised hurdle against botulism where spoilage bacteria is allowed to be present in certain food in order to cause spoilage before clostridium botulinum toxin formation takes place. The Montclair Tribune article of 20 April 1972 reported on work done by Dr. Richard A. Greenberg, director of research for Swift & Company, on behalf of the American Meat Institute. After studying canned ham he suggested that the unblemished botulism safety record of the curing industry in the USA may be due to the use of nitrites. So, clostridium botulinum will feature prominently in our considerations of the efficacy of nitrate and nitrite as antimicrobial agents, but other bacteria will also be considered.

The historical perspective

There are many reviews of the antimicrobial efficacy of nitrate and nitrite.  I rely exclusively on an review article written by Dr. R. Bruce Tompkin (1), the former Vice President for Food Safety, ConAgra Refrigerated Prepared Foods, published as part of  Davidson, M. P. et al’s,  2005 publication, “Antimicrobial in Food, Third edition.”  Dr. Tomkin is an exceptionally qualified man to write such a review.  He is a “microbiologist with more than 45 years in the food processing industry and one of the developers of HACCP.” (Maple Leaf Press release) He arranges the material chronologically which provided insight into why the research was conducted and why certain important points were missed early on.

It is in line with our approach of first understanding the historical background to any technology associated with the bacon industry.

10262188_10152414306796650_3469446068461831418_n

Observations

We remain with the story of nitrite and nitrate as science started to unlock the fascinating secret of its full effect in cured meats since the 1930s.  Most of the research focuses on canned and cured meat and we incorporate some of these important findings and see what can be applied to bacon.  The focus on research of nitrite and its effectiveness in canned cured meat makes sense since botulin formation occurs mostly from canned food and due to its deadly nature it is the priority organism in food safety. All consideration of preservatives must, therefore, start with the question if its effective against clostridium botulism, its spores and toxins.

“Unlike most other antimicrobial agents, there has been a long, controversial history over whether nitrate and nitrite have antimicrobial properties. ” (Davidson, M. P. et al.;  2005:  172)  An avalanche of investigations followed, elucidating the efficacy of these chemicals as antimicrobials.

Tanner and Evans (1933) said that sodium chloride (normal table salt), is the most effective component in curing mixtures and that sodium nitrite present, apparently produced no effect on organisms.  They then sited MacNeal and Kerr who said that potassium nitrate (saltpeter), in acid solutions had marked inhibitory efficacy.  They said that this effect was “incompatibly greater than that of salt.”   They believed that the claim of meatpackers that small amounts of nitrate in the pickle produced better preservation of the meat was born out by their results.  It seemed that nitrate was especially valuable in preventing a high degree of acidity of souring of meat. (Davidson, M. P. et al.;  2005:  172)

Brooks et al (1940) looked at bacon curing in the United Kingdom and concluded that bacon can be produced with nitrite only.  “They said that the characteristic cured flavour of bacon is primarily the result of the action of nitrite.  The conversion of nitrate to nitrite in commercial bacon curing brines is mainly the result of growth of micrococci.  The presence of nitrate or microbial action during the curing process is not essential for bacon flavour.”  Rapid chilling, as was practiced in the United States, was also not detrimental, as some speculated.  (Davidson, M. P. et al.;  2005:  172)

Tarr and Sutherland (1940) showed that nitrite delayed spoilage in fish.  Tarr (1941) revealed the importance of pH to the efficacy of nitrite.  At pH 7.01 there was little or no inhibition, but at p”H 5.7 and 6.0, complete or strong microbial inhibition occurred”. (Davidson, M. P. et al.;  2005:  173)

Jensen and Hess (1941) insisted that nitrite’s role was purely colour development and said that nitrate “exerts a definite inhibitory effect upon bacteria”.  They reported that nitrite reacts with protein during the heating process and is destroyed, “thus leaving the meat in much the same state as freshly cooked uncured meat”.  Scott (1955) agreed.  Jensen and Hess said that a combination of heat, nitrate, nitrite, and salt caused the destruction of anaerobic spores at much lower temperatures. (Davidson, M. P. et al.;  2005:  173)

Yesair and Cameron (1942) took up this concept and reached the conclusion that curing salts do not assist in thermal destruction but inhibit outgrowth.  Stumbo et al. (1945) reported that nitrite delayed germination, although salt was the stronger inhibitor.  Nitrate alone or in combination with other ingredients did not “appreciably influence spoilage.” (Davidson, M. P. et al.;  2005:  173)

Jensen et al. (1949) looked at the combination of heat and curing salts.  The magical temperature range where increased inhibition occurs in tubes of pork was between 50 deg C and 65 deg C, for 30 minutes.  Raising the temperature and heating it for longer times did not increase the effect.  However, looking at the effect of canned ham, increasing salt and nitrite increased inhibition.  Studying these effects of C. sporogenes 369 showed that increasing nitrate did not increase the inhibition. (Davidson, M. P. et al.;  2005:  173)

Steinke and Foster 1951 found salt to be major factor retarding botulinal outgrowth in temperature-abused products. Having a moderately high brine of 5.05% to 5.37% and a pH range of 6.1 to 6.5.  A combination of sodium nitrate, nitrate, and nitrite was the most inhibitory. (Steinke and Foster 1951)  (Davidson, M. P. et al.;  2005:  174) Bulman and Ayres (1952) found that a mixed cure of salt, nitrate, and nitrite yielded the maximum inhibition.  (Davidson, M. P. et al.;  2005:  174)

“Henry et al. (1954) found that at pH 7.5 or above, nitrite enhanced bacterial growth in curing brine. A pH of 5.6 to 5.8 was optimal for antibacterial efficacy.  At pH 5.3 or below, nitrite rapidly disappeared and was ineffective. Nitrite was more inhibitory in the presence of ascorbate.” (Davidson, M. P. et al.;  2005:  175)

Castellani and Niven (1955) said that nitrite was not known to have any practical preservative value against those organisms not inhibited by high salt in cured meat.  They also found that if a broth medium (pH 6.55) was autoclaved with glucose, a very small amount added nitrite prevented staphylococcal growth when incubated anaerobically. (Davidson, M. P. et al.;  2005:  175)

Lechowich (1956) showed that S. aureus growth can occur in any combination of salt, nitrite, and nitrate that is palatable and permissible.  (Davidson, M. P. et al.;  2005:  175)

Scott (1955) said that because nitrate exhibited relatively poor antimicrobial inhibition and nitrite, although effective, has been shown to be unstable, the control of salt concentration and resultant water activity is the most reliable bacteriostatic system for cured meats. (Davidson, M. P. et al.;  2005:  175)

As late as in 1957, Eddy was very cautious when expressing an opinion about the antimicrobial ability of nitrite.  He wrote: “Taken in their totality, these observations leave no doubt inhibition by nitrite is at least a possibility”. (Davidson, M. P. et al.;  2005:  176)

Tomkin summarizes the findings from 1950 to 1960 and state that it was found that salt, per se, had no antimicrobial effect, other than its possible influence on water activity. (Davidson, M. P. et al.;  2005:  176) He further states that by the end of the 1960s nitrite was recognized as an effective antimicrobial agent, but its value as a preservative in perishable meat was still in doubt.  The majority of studies focused and proved its effectiveness in shelf-stable canned meat. (Davidson, M. P. et al.;  2005:  176)

Brine content was shown to be an important factor in botulinal outgrowth and toxin formation.  (Davidson, M. P. et al.;  2005:  177)

Following 1960, the focus shifted towards the role of nitrite in the total inhibitory system in cured meat.  (Davidson, M. P. et al.;  2005:  177)

In 1962, Eddy and Ingram investigated “the survival of S. aureus in vacuum-packed, sliced bacon.  They found that staphylococci grew among the natural microflora of the bacon but growth was better when the number of saprophytic microorganisms was low and the storage temperature was high.  (Doyle, M.  1989.  :  476)

Gould (1964) showed that the toxicity of nitrite was 3 to 5 times greater at pH 6 than at pH 7.  (Davidson, M. P. et al.;  2005:  177)

Brownlie (1966) indicated that at pH 7.0, the presence of nitrite caused very little or no inhibition. At pH 6.0 and below, increasing the amount of nitrite from 25 to 200 μg/g caused progressively greater inhibition.  (Davidson, M. P. et al.;  2005:  178)

Brownlie (1966) has shown that nitrite was more inhibitory at 0°C than at the other temperatures tested (10°C and 25°C)  Several studies showed that salt becomes more inhibitory as storage temperatures are decreased in perishable vacuum-packed cured meat. (Davidson, M. P. et al.;  2005:  177)

Brownlie (1966) showed the inhibitory effect of sodium nitrite concentration, pH and temperature.  Brine content was shown to be an important factor in botulinal outgrowth and toxin formation. (Davidson, M. P. et al.;  2005:  177)

According to studies by Riemann Anon (1968), C. botulinum type A, the most toxic form, seemed to be completely inhibited by 4.5% brine at pH 5.3, 5.5% brine at pH 6.1, and 8.6% brine at pH 6.5.   (Davidson, M. P. et al.;  2005:  180)

Studies by Baird-Parker and Baillie (1974) indicated that when adding sodium nitrite and L-ascorbic acid as filter-sterilized solutions, the number of strains showing growth in broth was found to decrease with increasing nitrite (50, 100, 150, 200 μg/g), decreasing temperature (25°C, 20°C, 15°C), decreasing pH (7.0, 6.5. 6.0, 5.5), increasing salt (1.5%, 3.0%, 4.5%, 6.0% w/v), and decreasing inoculum level (106, 103, 101).  Adding L-ascorbic acid (1.0%) markedly increased the effectiveness of nitrite.  (Davidson, M. P. et al.;  2005:  180)

Adding hemoglobin resulted in a lower level of residual nitrite after processing, decreasing botulinal inhibition. (Davidson, M. P. et al.;  2005:  181)

Tompkin et al. concluded that Isoascorbate, ascorbate, cysteine, and ethylenediaminetetraacetic acid (EDTA) share a common function in meat, which later was demonstrated to be the sequestering of iron. (Davidson, M. P. et al.;  2005:  180)

Grever (1974) indicated that Bacillus species are less sensitive to nitrite than clostridia. (Davidson, M. P. et al.;  2005:  187)

Tompkin et al (1979) also showed that although isoascorbate enhances the antibotulinal effect of nitrite in freshly prepared perishable cured meat that is temperature abused, isoascorbate also reduces the efficacy of nitrite by causing more rapid depletion of residual nitrite.  (Davidson, M. P. et al.;  2005:  187)

According to Crowther et al. (1976),  studying mixtures of nitrite, nitrate, ascorbate and brine levels and their effect on botulinal toxins in vacuum packed back bacon, a higher percentage of samples analysed were toxic with the addition of 200 μg/g of nitrite than with 100 μg/g of nitrite. The addition of ascorbate enhanced the antibotulinal effect of 100 μg/g but not 200 μg/g of nitrite. These values raise a question concerning the conclusions that (1) protection was greater if the level of nitrite was increased to 200 μg/g and (2) sodium ascorbate at a level up to 2000 μg/g did not reduce the protection afforded by nitrite against C. botulinum. (Davidson, M. P. et al.;  2005:  187)

Crowther et al. (1976) also reported that S. aureus grew well in the medium-salted bacon, regardless of the level of nitrite or ascorbate. (Davidson, M. P. et al.;  2005:  189)

Shaw and Harding (1978) studied the effect of nitrate and nitrite on the microbial flora of Wiltshire bacon. The predominant flora of the bacon after curing consisted of micrococci, Moraxella species, and Moraxella-like bacteria. Omitting nitrate led to higher numbers of Moraxella species in the cured bacon.  However, bacon that was sliced and vacuum packaged developed a flora mainly of micrococci and lactics. Including nitrate in the bacon enhanced the growth of micrococci.  (Davidson, M. P. et al.;  2005:  189)

Shaw and Harding (1978) showed that because higher numbers of lactics were present in bacon with the lowest initial nitrite concentration, it was suggested that nitrite could be important in delaying the sour spoilage caused by the growth of lactics.  (Davidson, M. P. et al.;  2005:  189)

Various botulinal studies were conducted in the USA in the 1970’s.  It showed that vacuum-packaged bacon prepared with 0.7% sugar (sucrose) or more provides sufficient fermentable carbohydrate that naturally occurring lactics cause a decline in pH to inhibitory levels. (Davidson, M. P. et al.;  2005:  190)

The botulinal studies in the ’70s also showed that brine levels below 4.0% are not inhibitory to botulinal outgrowth. As the brine level exceeds 4.0%, outgrowth is increasingly delayed. If a lactic fermentation develops in the interim, the combination of relatively higher brine and decreasing pH can prevent botulinal outgrowth. (Davidson, M. P. et al.;  2005:  190)

These same studies showed that the level of residual nitrite at the time the bacon is abused influences the extent of the delay in botulinal outgrowth. The level of nitrite added to the product is not important, aside from the fact that the amount of added nitrite partially determines the level of residual nitrite. (Davidson, M. P. et al.;  2005:  190)

It also showed that the addition of ascorbate or isoascorbate can act in concert with residual nitrite to retard botulinal outgrowth in freshly produced bacon. However, ascorbate and isoascorbate can also have a negative effect by causing more rapid loss of residual nitrite during processing and storage. (Davidson, M. P. et al.;  2005:  190)

Nurmi and Turunen (1970) studied the effect of adding nitrite to a previously autoclaved broth medium (pH 6.0). Lactobacilli (78 strains), micrococci and staphylococci (24 strains), and Pediococcus cerevisiae (1 strain) were examined for their tolerance to nitrite in the presence and absence of 4.01% salt. At 200 μg/g growth was delayed or slower. At 40 μg/g growth was comparable to that in the control without nitrite, results were subsequently reported that showed the production of enterotoxin A to decrease as pH decreased, salt increased, and nitrite increased (Tompkin et al., 1973).

Morse and Mah (1973) studied the effect of glucose on enterotoxin B synthesis in a broth medium buffered to an alkaline pH (7.7). Adding glucose caused decreased toxin production.  Glucose repression of enterotoxin B production was also reported to occur at pH 6.0 but to a lesser degree than at pH 7.7 (Morse and Baldwin, 1973).

Bean and Roberts (1974, 1975)  The inhibitory effect of nitrite in the recovery medium increased with increasing salt content, decreasing incubation temperature, and decreasing pH. (Davidson, M. P. et al.;  2005:  190)

Zeuthen (1980) conducted studies on the effect of pH on the rate of microbial growth in sliced ham.  They found that the lower pH meat resulted in ham with a pH of 6.0 with residual nitrite after processing and the higher pH meat resulted in a ham with a pH of 6.35 with a higher residual nitrite level.  The brine level of both products was equal.  During 7 – 8 weeks of storage at 5 deg C, the rate of microbial growth was considerably slower in the sliced ham prepared with the lower pH meat.  (Davidson, M. P. et al.;  2005:  203)

In the 1980s, the USDA adopted a regulation for bacon that requires a maximum of 120 μg/g sodium nitrite and the addition of 550 μg/g sodium ascorbate or isoascorbate.  (Davidson, M. P. et al.;  2005:  203)

It was also shown during this period that the mechanism of nitrite inhibition differs in different bacterial species.  (Davidson, M. P. et al.;  2005:  203)

In 1988, the USDA initiated a series of increasingly restrictive policies on the rate of chilling for perishable cured meat manufactured under USDA inspection.    Dr. Tompkin continues that this is a case where the epidemiologic data indicate a negligible public health concern for cured meats but the evidence from challenge studies and predictive modeling suggests otherwise.  He notes that the situation is a reminder of Morris Ingram’s frustration with the increase in research on nitrite’s role in botulinal inhibition in the 1970s.  At the time he stated, ” What we need at the present time, in my opinion, is not more inoculated pack experiments but a rationale for interpreting them” (Ingram, 1974).” Since 1990 there has been an increased interest of L. monocytogenes in ready-to-eat foods.

McClure et al (1991) found the efficacy of sodium nitrite to be temperature and pH-dependent.  At a pH value of 6.0 sodium nitrite had little effect in delaying the time to detect visible growth except at the highest level tested (200 ppm) and a temperature of 15 deg C or below.  At pH 6.0 and 5 deg C, no growth was observed with any of the levels of sodium nitrite evaluated (50, 100, 200, 400 μg/g).  Buchanan and Golden, 1995; Buchanan et al., 1997) conducted an extensive series of experiments that led to the conclusion that nonthermal inactivation of L. monocytogenes by sodium nitrite is pH-dependent and related to the concentration of undissociated nitrous acid.  (Davidson, M. P. et al.;  2005:  203)

Duffy et al. (1994) inoculated a variety of vacuum-packaged cooked sliced meat with L. monocytogenes and found the lag time increased and the rate of growth decreased at 0 deg C and 5 deg C with the addition of sodium nitrite (0 to 315 μg/g).   The effectiveness of sodium nitrite was significantly increased with the addition of sodium ascorbate. (Davidson, M. P. et al.;  2005:  203)

eben 4

Points of Application

Here are a few practical applications that flows from the consideration of nitrite and nitrate in bacon.

– An important economic and food safety consideration is shelf life.  In order to extend shelf life, good manufacturing practices, a thorough food safety program and using the correct heat, freezing and pH during processing are as important as antimicrobial chemicals.  Some argue that these may have the ability to replace most antimicrobial’s in food. An example of this is the contention that much of the improved shelf life in the US on bacon and poultry products is “attributed to improvements in sanitation between cooking and packaging as a requirement to control Listeria contamination”.  (private communication with Dr. Tompkin)

– It is possible, in manufacturing certain products, to reduce the pH.  We suggest manipulating the pH of the meat to levels of between 5.6 and 5.8.  Not below 5.3 since reducing the pH will increase the rate of nitrite depletion  (private communication with Dr. Tompkin) and 5.3 has been shown to be a threshold.

– Use nitrite and salt in combination with a low temperature, targeting an internal core temp of between 50 and 65 deg C for at least 30 minutes.

–  The goal of keeping the meat temperature below 5 deg C from receiving meat till before smoking/ cooking and then rapid chilling and freezing and keeping the finished product below 5 deg C is an excellent way of increasing the lag time and the reduce the rate of growth of L. monocytogenes.  As a general policy, meat must be kept below this during processing.

–  Related to the greening of bacon.  “Greening is due to the growth of certain other lactobacilli which also occur on cured meats and is a very old problem.  It is a major problem at times if cooked product is held in storage allowing for the lactobacilli to multiply and then the product is used as rework into a new product.  Over time the repetitive addition of aged rework leads to a high population of lactobacilli that are exceptionally heat resistant. They are microaerophilic meaning they can not tolerate much oxygen and grow well under the perimeter of sausages or in vacuum packaged meats. Upon opening the packages the product turns green.” (private communication with Dr. Tompkin)

Another reason often cited for a green discolouration in cured meat is nitrite burn.  It is caused by a combination of excessive levels of nitrite and reduced pH (Deibel and Evans, 1957).  The levels that nitrite is used in cured meat is so low that greening in bacon is unlikely to occur as a result of nitrite and reduced pH.  (private communication with Dr. Tompkin)

10170683_10152501991376650_4986278986190926576_n

Nitrite’s role in cured meat is far more than only colour and taste.  It is a key component of a very complex environment with definite antimicrobial efficacy.  It is an effective hurdle against clostridium botulinum.  Its antimicrobial efficacy extends to other organisms, the level of which differs from organism to organism.  It is definitely an important general antimicrobial hurdle.

Regarding nitrate, enough early research has been done that show efficacy if it’s used in conjunction with nitrite and salt to warrants its inclusion in brine curing mixes. The efficacy of nitrate and nitrite is strongly tied to brine composition, pH, heat treatment and adding complementary chemicals. The story of saltpeter (potassium nitrate) and sodium nitrite is epic in the true sense of the word.

It is a huge responsibility to not only produce the best bacon on earth, but also the safest bacon on earth!  This is a consideration that never featured high on my agenda in the early years, but as time went by,  I started becoming obsessed with it.  I know you will have many questions and you can contribute with the most recent research on the subject.  Please continue to update this letter in particular when you eventually combine them all into a book.

I wish it was December already that I could see you again.  We count the days!

Lots of love from Cape Town,

Dad and Minette.


Further Reading

Concerning Nitrate and Nitrite’s antimicrobial efficacy – chronology of scientific inquiry

Clostridium Botulinum – the priority organism


green-previousgreen-home-icongreen-next


(c) eben van tonder

Bacon & the art of living” in book form
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Notes

(1)    Dr. Tompkin is retired and currently associated with the School of Applied Technology as part of the Illinois Institute of Technology.  For his background, see https://appliedtech.iit.edu/people/bruce-tompkin.

References

Davidson, P. M. et al.  2005.  Antimicrobials in Food, Third Edition.  CRC Press.

Doyle, M.  1989.  Bacterial Pathogens.  Marcel Dekker, Inc.

Emmeluth, D.  2010.  Botulism.  Infobase Publishing.

Jay. M. J. et al.  2005.  Modern Food Microbiology. Springer Science + Business Media.

The Centralia Enterprise and Tribune.  Centralia, Wisconsin.  25 January 1896.

The Laredo Times.  Laredo, Texas.  1 December 1896.

Maple Leaf Press release:  http://investor.mapleleaf.com/phoenix.zhtml?c=88490&p=irol-newsArticle&ID=1363993&highlight=

McCarthy, M. Chairman of the Committee of nitrite and alternative curing agents in food.  Et al.  1981.  The Health Effects of Nitrate, Nitrite, and N- Nitroso Compounds.  National Academy Press.

Montclair Tribune.  Montclair, California. 20 April 1972.

Sterba, J. P.. 28 April 1982.  The History of Botulism.  The New York Times.

http://medical-dictionary.thefreedictionary.com/Clostridium+putrificum

Images

Image 1:  Clipping from newspaper article:  Montclair Tribune (Montclair, California), 20 April 1972.

Chapter 11.04: The Direct Addition of Nitrites to Curing Brines – The Spoils of War

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


The Direct Addition of Nitrites to Curing Brines – the Spoils of War

September 1959

Dear Tristan,

I thought I would write your sister this time around but then realised that I have to finish my tale of how sodium nitrite became the most popular way to add nitrite to curing brines.  The story is epic and I don’t want you to lose the thread.

From a scientific standpoint, using sodium nitrite as the source of nitrite is an important progression of the technology of bacon curing but there was a problem.  The general public saw sodium nitrite as a poison and the cost was exorbitant.  It would require more than just an energetic and brilliant Master Butcher from Prague to convince the world that it is an improvement in curing technology.

Early Public Perception about Nitrite

Between the mid-1800s and early 1900s, industry and informed members of the public knew nitrite as an ingredient in medication [8] (Vaughn E, et al.;2010;  Jul–Aug; 18(4): 190–197) and sodium nitrite as an intermediary in the chemicals dye industry. (Concerning Chemical Synthesis and Food Additives)  Most people, however, knew nitrite as a toxic chemical that kills livestock and people if the drinking water has even small traces of it.  Such was the concern that nitrite levels in drinking water were reported in local newspapers every week to alert the public to possible contamination.  It is, therefore, no wonder that the public and authorities were very skeptical about its use in food.

At the beginning of the 1900s, scientists developed a detailed understanding of the chemistry of curing which clearly showed the priority of nitrites in the process.  In contrast to this, the general public and their elected officials were against the direct use of nitrites in food.  As is many times the case, the scientific understanding was not general knowledge yet.

We now delve deeper into the story and zoom in on developments in three parts of the world, Prague, Germany and in the USA, Chicago.  Events, dates, and places will start to overlap and two processes will become very important, the electric arc method of extracting nitrogen from the atmosphere and the Haber process.

As we do so, it is important to understand one more point in chemistry namely the close proximity of nitric oxide (CodeCogsEqn (13)), nitrous acid (HNO2), nitric acid (CodeCogsEqn (46)), nitrite (CodeCogsEqn (17)), nitrate (CodeCogsEqn (47)) and ammonia (CodeCogsEqn (48)).  All have a nitrogen atom as part of either the molecule or the ion.  The Haber process yields ammonia (CodeCogsEqn (48)) and the electric arc process, either nitrous acid (CodeCogsEqn (19)) or nitric acid (CodeCogsEqn (46)).  From any of these, nitrite (CodeCogsEqn (17)) can be formed.    (Webb, H. W.; 1923)

Germany 1910 – 1920 – the Race to Access Atmospheric Nitrogen

austerity-for-middle-class-meat-market
Austerity for the middle class in Germany during the Great War.

By the end of the war, the largest stockpiles of nitrite in the history of humanity were in Germany.  It was created by the most productive chemicals industry in the world.  How this happened is fascinating!

By the late 1800s, it was apparent that the world’s growing populations will not be fed unless atmospheric nitrogen can be harvested.  Solving the problem of how to do this became one of the biggest priorities of science. After an intense search and various processes tested on an industrial scale, including the electric arc method, the German chemist, Fritz Harber finally solved the problem with the help of Robert Le Rossignol who developed and build the required high-pressure device to create ammonia from atmospheric nitrogen.

The process was first demonstrated in 1909.  The German dyes manufacturer, BASF acquired the technology and under the leadership of Carl Bosch, the first Haber-process factory went into operation in Oppau, Germany in 1913. (Concerning the direct addition of nitrite to curing brine),

As a direct consequence of this development, Germany was no longer reliant on saltpeter from Chili (sodium nitrate) as fertilizer to feed its massive agriculture industry.  Another consequence of the Haber-process is that it made World War One possible on an industrial scale.  Nitrogen is key in ammunition production.  Germany and its allies could escalate the war to a never before seen level.

When ammonia is made from atmospheric nitrogen, it was possible to produce nitrates and nitrites.  The concept of using nitrites as a preservative in food was not something new.  There are good examples of Germans toying with the use of nitrite in food, even before the war.  The German scientist,  Glage (1909) wrote a pamphlet where he outlines the practical methods for obtaining the best results from the use of saltpeter in the curing of meats and in the manufacture of sausages. (Hoagland, Ralph,  1914: 212, 213)

Glage gives for the partial reduction of the saltpeter to nitrites by heating the dry salt in a kettle before it is used.  It is stated that this partially reduced saltpeter is much more efficient in the production of color in the manufacture of sausage than is the untreated saltpeter (Hoagland, Ralph,  1914: 212, 213), pointing to the fact that nitrite was being considered as a preservative and for its effect of meat colour, from the earliest times.

This means that by the 1910s, German scientists tried to solve the problem by still using saltpeter as a starting point to the reaction but getting to a reduced state faster.  The line of thinking of using nitrate as the starting point was finally perfected by the Irish, Danes, and British who allowed the reduction to take place at the normal pace through bacterial means.

It was however not before BASF’s new Haber process came into operation that sodium nitrite became generally and cheaply available which meant for curing of meat that it could be added directly without allowing a bacterial reduction of nitrate to nitrite first. Solving the problem by using sodium nitrite was now a serious possibility.  The Great War provided the environment to “motivate” the entire meat-curing industry to change from saltpeter to sodium nitrite when saltpeter was suddenly not available for curing, survival was linked to speed of curing and public perceptions were put aside.

A document from the University of Vienna would fill out the story.  According to it, saltpeter was reserved for the war effort and was consequently no longer available as curing agent for meat during World War One. (University of Vienna). It was reserved for the manufacturing of explosives, and for example, the important industry of manufacturing nitrocellulose, used as a base for the production of photographic film, to be employed in war photography.  (Vaupel, E.,  2014: 462)  It gets even better.  The prohibition on the use of saltpeter gives us the background of why people started using sodium nitrite as curing salt instead of saltpeter in Germany.

In August 1914, the War Raw Materials Department (Kriegsrohstoffabteilung or KRA) was set up under the leadership of Walther Rathenau.  It was Rathenau who was directly responsible for the prohibition on the use of saltpeter.  (11) He, therefore, is the person in large part responsible creating the motivation for the meat industry in Germany to change from saltpeter to sodium nitrite as curing medium of choice for the German meat industry during World War One. It was the vision and leadership of Walther Rathenau, the man responsible for restricting the use of saltpeter, which drove Germany to produce synthesized Chilean Saltpeter.  He saw this as one of the most important tasks of his KRA.  He said:  “I initiated the construction of large saltpeter factories, which will be built by private industries with the help of governmental subsidies and will take advantage of recent technological developments to make the import of saltpeter entirely unnecessary in just few months“.  (Lesch, J. E.,  2000:  1)

Fritz Harber was one of the experts appointed by Rathenau to evaluate a study on the local production of nitric acid. During World War One production was shifted from fertilizer to explosives, particularly through the conversion of ammonia into a synthetic form of Chile saltpeter, which could then be changed into other substances for the production of gunpowder and high explosives (the Allies had access to large amounts of saltpeter from natural nitrate deposits in Chile that belonged almost totally to British industries; Germany had to produce its own). It has been suggested that without this process, Germany would not have fought in the war, or would have had to surrender years earlier.”  (www.princeton.edu)

So it happened that Germany became the leader in the world in synthesised sodium nitrate production and it effectively replaced its reliance on saltpeter from Chile with synthesised sodium nitrate, produced by BASF and other factories. As a result of the First World War, sodium nitrite was produced at levels not seen previously in the world and in large factories that were built, using the latest processing techniques and technology.  Sodium nitrite, like sodium nitrate, was being used in the production of explosives.  Nitroglycerin is an example of an explosive used extensively by Germany in World War One that uses sodium nitrite in its production.

amyl-nitrite-3d-ballsBall-and-stick model of Amyl nitrite used in the production of nitroglycerin. Amyl nitrite is produced from sodium nitrite. The diagram shows the amyl group attached to the nitrite functional group.

Sodium nitrite and the coal-tar dye industry

The importance of the manufacturing cost of nitrite and the matter surrounding availability can be seen in the fact that sodium nitrite has been around since well before the war.  Despite the fact that it was known that nitrite is the curing agent and not nitrate, and despite the fact that sodium nitrite has been tested in meat curing agents, probably well before a clandestine 1905 test in the USA,  it did not replace saltpeter as the curing agent of choice.  is was due to cost restrictions as much as public opinion.

The technology that ultimately is responsible for synthesising Chilean Saltpeter and made low-cost sodium nitrite possible was incubated in the coal-tar dye and textile industry and in the medical field.  The lucrative textiles and dye industry was the primary reason for German institutions of education, both in science and engineering to link with industry, resulting in strong, well-organised skills driven German economy. For example, “Bayer had close ties with the University of Göttingen, AGFA was linked to Hofmann at Berlin, and Hoechst and BASF worked with Adolph Baeyer who taught chemists in Berlin, Strasbourg, and Munich.” (Baptista, R. J..  2012:  6)

“In the late 1870s, this knowledge allowed the firms to develop the azo class of dyes, discovered by German chemist Peter Griess, working at an English brewery, in 1858.  Aromatic amines react with nitrous acid to form a diazo compound, which can react, or couple, with other aromatic compounds.” (Baptista, R. J..  2012:  6)

Nitrous acid (HONO) is to nitrite (NO2-) what nitric acid (NO3) is to nitrate (NO3-). According to K. H. Saunders, a chemist at Imperial Chemical Industries, Ltd., Martius was the chemist to whom the introduction of sodium nitrite as the source of nitrous acid was due.   (Saunders, K. H., 1936:  26)

The Economic Imperative

The simple fact is that ammonia can be synthesized through the direct synthesis ammonia method at prices below what can be offered through Chilean Saltpeter.  (Ernst, FA.  1928: 92 and 100)  Sodium Nitrite can be supplied at prices below Chilean saltpeter and this made sodium nitrite the most effective curing agent at the lowest price since World War One.

As an example of the cost differences, the price of Nitric Acid (HNO3) from direct synthesis in 1928 was $23.60 per ton HNO3 plus the cost of 606 lb. of NH3 by-product and from Chilean Nitrate at $32.00 per ton of HNO3, plus the cost of 2840 N NO3 by-product.  (Ernst, FA.  1928: 112)

The Advantage of Scale and Technology

By 1927, Germany was still by far the world’s largest direct syntheses ammonia producer.  Production figures for the year 1926/ 1927  exceeded Chilean saltpeter exports even if compared with the highest levels of exports that Chilean saltpeter ever had in 1917.  A total of 593 000 tons of nitrogen was fixed around the world in 1926/27.  Of this figure, Germany produced 440 000 tons or 74%.  The closest competitor was England through the Synthetic Ammonia and Nitrates Ltd. with a total capacity of 53 000 tons of nitrogen per year.  (Ernst, FA.  1928: 119, 120)

In the USA, seven direct synthesis plants were in operation with a combined capacity of 28 500 tons of nitrogen per year.  (Ernst, FA.  1928: 120)

Supporting Evidence from the USA

The thesis that before the war, the production of sodium nitrite was not advanced enough for its application in the meat industry (resulting in high prices and low availability) is confirmed when we consider the situation in the USA.

The first US plant for the fixation of atmospheric nitrogen was build in 1917 by the American Nitrogen Products Company at Le Grande, Washington.  It could produce about one ton of nitrogen per day.  In 1927 it was destroyed by a fire and was never rebuild. (Ernst, FA, 1928: 14)

An article in the Cincinnati Enquirer of 27 September 1923 reports that as a result of cheap German imports of sodium nitrite following the war, the American Nitrogen Products Company was forced to close its doors four years before the factory burned down.  The imports referred to, was as a result of Germany selling their enormous stockpiles of sodium nitrite at “below market prices” and not directly linked to a lower production price in Germany, even though this was probably the case in any event. ( The Cincinnati Enquirer ( Cincinnati, Ohio), 27 September 1923. Page 14.)

The meat curers initially used sodium nitrite directly (i.e. not mixed with sodium chloride).  It looks similar to regular table salt.  Several cases of poisoning were reported including the mass poisoning of 34 people including a child who died in Leipzig.  The Government promptly banned its use (Hans Marquardt , et al, 1999:  21), but in the prevailing war conditions, and with the Government’s inability to stamp out the massive black market in foods, there can be no doubt that this practice persisted throughout the war.

The practice of colouring curing salt containing sodium nitrite pink, probably stems from this indecent of incidents like this, in order to prevent people from confusing sodium nitrite with table salt.  The practice became law in most countries in subsequent years and the remains to this day.  The Vienna University document indicates that the fast curing of sodium nitrite was recognised and after the war, the ban was lifted.

Walter Rathenau’s actions may have motivated the change, but it was the developments in synthesizing ammonia, sodium nitrate and sodium nitrite which provided the price point for the compound to remain the curing agent of choice, even after the war and after the prohibition on the use of saltpeter was lifted.

By 1909, the world production of inorganic nitrogen by the electric arc method and some miscellaneous processes were standing at a combined 3000 metric tons.  The Haber process was not invented yet.  One year after Ladic started working as a meat curer, by 1913, the arc and miscellaneous processes yielded 18 000 metric tons and the Haber process, 7000 metric tons.

By 1917, the arc and miscellaneous processes delivered 30 000 metric tons and the Haber process, 100 000 metric tons.  This was 5 years after Ladic learned the art of curing and possibly started using sodium nitrite in meat curing.  Over these five years, he has seen a dramatic increase in the availability of nitrite and therefore a reduction in nitrite prices. In 1920, the Haber process delivered a staggering 308 000 metric ton of nitrogen, compared to the 33 600 metric tons of the arc and miscellaneous processes. (Scott, E. Kilburn. 1923; : 859–76)

World War One broke out on 28 July 1914 and lasted until 11 November 1918.  When the war ended, Germany had huge stockpiles of sodium nitrite (along with many other war-chemicals).  They had to pay a massive war debt and raise the German economy from the dead.  These were desperate times and Germany threw its full energy and industriousness behind this effort.  The effort focused on the lucrative market of the USA.

The USA – 1910’s – Nitrite on Trial

The drama of the sale of German nitrites played itself off in the USA and particularly in Chicago.  This directly led to the creation of a legendary curing salt, Prague Salt, which later became Prague Powder.  We used Prague Powder all the years that I was with Woodys.  These events played off in America.

We begin our US story by looking at public and government views on nitrite.  During the 1910s, the USA wrestled with the question of whether nitrites in food constitute adulteration and it’s consideration created its own epic drama.

Vastly opposing views were held in relation to preservatives and colourants generally.  Prof. Julius Hortvet, a chemist at the Minnesota Dairy and Food Commission said in an address delivered on 16 July 1907, at the Eleventh Annual Convention of the Association of State and National Food and Dairy Departments, in Jamestown, “Some state laws go so far as to inflict fine and imprisonment for making an article appear better than it really is.” He presented the opposing view when he said that he believes that “if we must have legislation in regards to this, it would be wiser to reserve it and punish the man who did not make his food product as attractive as possible.”  (American Food Journal; 1907)

In his speech, he made the following prophetic comment about saltpeter which in years to come would become one of the dominant arguments for the use of nitrite in foods.  He said that “we know..that certain substances, as salt and saltpeter, have caused death from the effects of large doses.”  He then draws a brilliant comparison between these products and alcohol when he said that “alcohol is classed as a poison.” His point was that what is good for alcohol, which is a poison if consumed in high concentrations and large volumes, should be good for saltpeter (i.e. limit the amount of nitrate and nitrite in foods instead of banning it altogether, as is the case with alcohol).  “In short,” he said, “the whole question sometimes is relative.” (American Food Journal; 1907)

He was “not contending that certain articles commonly used in…food may or may not under certain circumstances act as a poison.”  He was “simply defending… against two possible evils:  first, the addition to…food of any substances that will tend to augment the possibilities of harm arising from our daily diet.” His second point sounds like one directed to the use of nitrite and its medicinal use when he said that “he is secondly defending against,” the addition to … foods of substances having therapeutic or even toxic properties by persons unqualified to prescribe such substances.” (American Food Journal; 1907)  He is possibly tripped up by a lack of scientific understanding about nitrites at the time, but both cautionary notes are commended and points that I have for years lived by.

In the 1910s, the US Department of Agriculture had the right to promulgate “standards of purity for food products and to determine what is regarded as adulteration therein.”  (American Food Journal; 1907 vol 2 no 2, 15 Feb 1907, p43 )  Whether these standards would become law was an open question at this stage.  If there was a dispute about a substance, it was heard by a special organ of the US Department of Agriculture, the Referee Board of Consulting Scientific Experts, created in 1908.

The battleground about the use of nitrites itself was not the meat industry.  It seems that the meat industry considered and possibly used it in secret.  The battle played out in its use as a bleaching agent in flour.  The controversy came to a head in a landmark court case in 1910 related to flour.

The millers were infuriated because the attorney general opted for a jury trial instead of referring the matter to the Referee Board of Consulting Scientific Experts.  (Chicago Daily Tribune; 7 July 1910; Page 15)  I can only suspect that he was himself against the use of nitrites in food and probably did not want scientists to decide.

A court case was brought by the US Federal Government against the Mill and Elevator Company of Lexington, Nebraska.  The charge was that they adulterated and misbranded flour and sold it to a grocer in Castle, Missouri. The government seized as evidence 625 sacks of flour from the grocer.  The court case lasted five weeks.  The case was brought by the government under the pure food and drug act of 1906.  (Chicago Daily Tribune; 7 July 1910; Page 15)  This is an act “for preventing the manufacture, sale, or transportation of adulterated or misbranded or poisonous or deleterious foods, drugs, medicines, and liquors, and for regulating traffic therein, and for other purposes.”  (www.fda.gov)

The government contended that “poisonous nitrites are produced in the flour by bleaching.” They did not share the view of Prof. Julius Hortvet that we looked at earlier who said that these matters are relative to the amount of the substance used since alcohol is also a poison if used in the right quantity.  The Federal Government said that “any amount of poison introduced into food is an adulteration.”  (Chicago Daily Tribune; 7 July 1910; Page 15)

The issue was that as much as 80% of the flour produced in the USA during that time was bleached with a nitrogen peroxide process.  Flour naturally has a creamy tint.  The cheaper the grade, the more creamy it is.  In ages past, flour was bleached simply by age. The chemical bleaching process with nitrogen peroxide instantly changes the yellowest flour whiter than the highest grade.  The process results in residue traces of nitrous and nitric acid being left in the flour which produce nitrites and nitrates.  (Chicago Daily Tribune; 7 July 1910; Page 15)

The defense argued that “nitrates (and nitrites) were present in such small quantities that no man could eat enough bread at one time to be poisoned by them.”  (Chicago Daily Tribune; 7 Jul 1910; Page 15)  The government contended that “if this view were upheld by the courts all foodstuffs manufactured could introduce quantities of poison into their products, infinitely small in each case, but devastating in their cumulative effect.” (Chicago Daily Tribune, 7 Jul 1910, Thu, Page 15)  (I will look at the arguments and provide an overview of how the international food industry answered it in the years following 1910 in a separate letter)

This was a case of huge importance to the industry as can be seen from the list of people called upon by the defense.  Pierce Butler of St Paul acted as a special attorney for the defense.  (Chicago Daily Tribune; 7 Jul 1910;  Page 15) Whether he still had the position in 1910 when the case was heard must be verified, but he was a lawyer of such stature that in 1908, Butler was elected President of the Minnesota State Bar Association.  From 1923 to 1939 he served as Associate Justice of the Supreme Court of the United States.  (saintpaulhistorical.com)

Apart from Butler, “a large staff of distinguished lawyers fought for the company who’s flour was seized, and for the millers of Nebraska, the millers of Kansas, and the company who makes the bleaching machines.  Among the experts who testified were all the toxicologists who testified in a previous landmark case (the Swope case), professors of chemistry and medicine from twenty universities, doctors, bakers, millers, and housewives.” (Chicago Daily Tribune; 7 Jul 1910; Thu, Page 15) After seven hours of deliberation, the jury returned a verdict in favour of the government upholding the charge that the bleached flour was both adulterated and misbranded.  (Chicago Daily Tribune; 7 Jul 1910; Thu, Page 15) It is fair to conclude that by 1910, nothing was more sensitive in food production than the presence of nitrites and the use of sodium nitrite in food was highly controversial.

Sodium Nitrite Tested in Meat Curing in Chicago

In the early 1900s, in Chicago, the powerful meatpacking companies set up by Phil Armour, Gustav Swift, and Edward Morris were all looking for ways to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.”   (The Indiana Gazette.  28 March 1924). The earliest reference to a test of meat curing with sodium nitrite in the USA places a secret experiment conducted where sodium nitrite was used to cure meat in 1905. [11] This was probably done in Chicago.  When the “Pure Food and Drug Act and Meat Inspection Act” of 1906 was promulgated, it made the use of sodium nitrite in food illegal.  It was not specifically forbidden, but the act was applied, for example in the 1910 court case we just looked at, in such a way that it was seen as making its use in food illegal.

During the 1910s a very interesting article appeared in Chicago that places a company with the technology to produce sodium nitrite in the same city.  It appeared in the American Food Journal of 15 February 1907 entitled “Cheap Nitrogen.” It said that a Chicago-based company was producing nitric acid by the electric arc method invented by Prof. Mościcki of the University of Freiburg, Switzerland, that we looked at before.  The method, in reality, was able to produce both nitric and nitrous acid  (US patent US1097870) and dates back to 1901. (cesa-project.eu)  The article states that the process made its production “cheap enough to be commercially applicable.”  (American Food Journal.  Vol 2.  No 2.  15 Feb 1907, p29)  The entrepreneur behind this company was William M. Thomas, who set an experimental plant up in Marshfield Avenue, Chicago. His main goal was probably to produce fertilizer.  (Chicago Sunday Tribune, Nov 10, 1907)

We have already referred to the electric arc method several times.  Mościcki, the inventor of the process was the former assistant to Józef Wierusz-Kowalski (1896), professor of physics, and rector (provost) at Albert-Ludwigs University in Freiburg, Switzerland. Prof Mościcki was an interesting person.  After a very successful academic career and a career as an inventor, he became the 3rd president of the second Polish Republic.  He was in office from 4 June 1926 to 30 September 1939.  Another interesting fact relates directly to his invention is that in Bern, Switzerland, his patent application was handled by none other than Albert Einstein.

“In 1905 Einstein evaluated Prof Mościcki’s special arc furnace which employed a rotating electric arc and was used for the production of nitric (and nitrous) acid…” ” The field generated by an electromagnet was used to rotate the arc. The 26-year-old physicist (Einstein) and the still young (38) but already renowned inventor and scholar (Prof Mościcki’s)  met and discussed the patented idea. Einstein was curious to know why an electric arc changed its orientation in a magnetic field.” Prof Mościcki’s became a successful businessman in Switzerland.   (Zofia Gołąb-Meyer Marian.  2006)  [12]

When we looked at the career of Ladic Nachtmullner, we have seen that the first production of nitrous acid in Switzerland was in 1910, during World War One based on the invention of Prof Mościcki.  This happened “immediately after his procedure was patented.” “A factory was opened in Chippis in Wallis canton, Switzerland.”  “In the subsequent years, this procedure was substantially perfected and nitrous acid could be supplied not only to Switzerland but also to neighbouring countries.”  (cesa-project.eu)

What is interesting in relation to Chicago is that the American Food Journal article says that the Chicago company was already in production by 1907 manufacturing nitric acid “in a small way” from free nitrogen, using the technology invented by Mościcki’s.  (American Food Journal.  Vol 2.  No 2.  15 Feb 1907, p29)

In the USA the fixation of atmospheric nitrogen was a priority and they knew the lagged behind Germany.  The first US plant for the fixation of atmospheric nitrogen was built in 1917 by the American Nitrogen Products Company at Le Grande, Washington.  It could produce about one ton of nitrogen per day.  In 1927 it was destroyed by a fire and was never rebuild. (Ernst, FA, 1928: 14)

An article in the Cincinnati Enquirer of 27 September 1923 reports that as a result of cheap German imports of sodium nitrite following the war, the American Nitrogen Products Company was forced to close its doors four years before the factory burned down. We will consider America’s response to these cheap imports momentarily. ( The Cincinnati Enquirer ( Cincinnati, Ohio), 27 September 1923. Page 14.)

We can conclude then with great certainty that there was at least one company in Chicago by 1907 that could produce sodium nitrite.  Was this venture funded by the meatpacking companies?  It is a question for further discovery.  A much larger project got underway in 1917, but by 1923, the USA was not in a position to supply material quantities of sodium nitrite.

Nitrite Curing Known in the USA Pre-1925

A document, published in the USA in 1925 shows that sodium nitrite as a curing agent has been known well before 1925. The document  was prepared by the Chicago based organisation, The Institute American Meat Packers and published in December 1925.  The Institute started as an alignment of the meatpacking companies set up by Phil Armour, Gustavus Swift, Nelson Morris, Michael Cudahy, Jacob Dold and others with the University of Chicago.

A newspaper article about the Institute sets its goal, apart from educating meat industry professionals and new recruits, “to find out how to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.”   (The Indiana Gazette.  28 March 1924). The document is entitled, “Use of Sodium Nitrite in Curing Meats“, and it is clear that the direct use of nitrites in curing brines has been practiced from earlier than 1925. (Industrial and Engineering Chemistry, December 1925: 1243) The article begins “The authorization of the use of sodium nitrite in curing meat by the Bureau of Animal Industry on October 19, 1925, through Amendment 4 to B. A. I. Order 211 (revised), gives increased interest to past and current work on the subject.” Sodium Nitrite curing brines would therefore have arrived in the USA, well before 1925.

It continues in the opening paragraph, “It is now generally accepted that the salpteter added in curing meat must first be reduced to nitrite, probably by bacteria, before becoming available as an agent in producing the desirable red color in the cured product.  This reduction is the first step in the ultimate formation of nitrosohemoglobin, the color principle.  The change of nitrate to nitrite is by no means complete and varies within considerable limits under operating conditions.  Accordingly, the elimination of this step by the direct addition of smaller amounts of nitrite means the use of less agent and a more exact control.”

Aftermath of the Great War

At the end of World War One, England had its own stockpiles of nitrite to dispose of. Sodium nitrite in the UK appeared for sale in an advertisement in the Times of London on 1 May 1919, 6 months after the armistice.  (The Times, London)

The stockpile of the English was dwarfed by what was available from Germany. The German Government did not wait long before they started selling their war stockpile.  An article appeared in The Watchman and Southron on 19 Feb 1921 and shows that German goods, especially chemicals have been making its way to the USA in such quantities that it was seen as a threat to the local industry.

Restrictions on German Sodium Nitrite in the USA

Our three worlds of Germany, Prague, and the USA now merge. The Detroit Free Press (Detroit, Michigan) reported on 14 Jan 1921 that “large stocks of imported sodium nitrite are offered at extremely low prices by agents of German manufacturers.”

Some of the tactics used by Germany to get goods into the USA, including goods subjected to presidential restrictions, were to import goods through the “concealment of the origin of shipment.”  German chemicals, subject to such restrictions have been making their way into the USA “appearing as having been shipped from Switzerland, Italy and elsewhere.  “Also, there has been extensive smuggling.”  The article states that the German plans to sell their products in the USA and economic domination have been made as early as May 1919.  (The Watchman and Southron, 19 Feb 1921, page 3)

Great emphasis is placed on sodium nitrite.  The author of an article that appeared in The Watchman and Southron, 19 Feb 1921, misread its importance when it was reported that “sodium nitrite would seem to be of minor importance.”  “Since the first of the year (Jan 1921), the Germans have glutted the American sodium nitrite market, threatening to destroy the hitherto prosperous American industry, and no relief has yet been obtained through the war trade board.”  (The Watchman and Southron, 19 Feb 1921, page 3)

In April 1921, the call made in February for greater control over the import of sodium nitrite was answered when the war trade board in the USA placed an embargo on the importation of sodium nitrite.  In the future, it could only be imported under license.

An article that appeared in the Detroit Free Press, 22 April 1921, reported that the goal of the embargo was to “check the heavy imports from Germany and Norway which have swamped the market in the country and reduced prices to a level below the cost of manufacture in the United States.  (Detroit Free Press, 22 Apr 1921, Page 18)

On 7 May 1924, The Indianapolis News, reports that the tariff for importing sodium nitrite was increased by a massive 50% from 3 cents a pound to 4.5 cents per pound.  This was the maximum duty permitted under the Fordney-MacCumber tariff act.  The additional duty was levied in response to a petition filed by the American Nitrogen Products Company of Seattle, Washington.  (Detroit Free Press, 22 Apr 1921, Page 18) In June it is reported that the measures were effective and that sodium nitrite prices were increasing.  (Detroit Free Press, Detroit, Michigan, 11 June 1921, p4)

German Sodium Nitrite Appears as Curing Agent in the USA – Ingredients for Deceit.

union stock yard chicagoUnion Stock Yard, Chicago, USA, C 1920

Then arrived 1925 and everything seems to change as sodium nitrite became available through the Griffith Laboratories in a curing mix for the meat industry.  They described Prague Salt and how they came upon the concept in official company documents as follows, “The mid-twenties were significant to Griffith as it had been studying closely a German technique of quick-curing meats.  Short on manpower and time, German meat processors began curing meats using Nitrite with salt instead of slow-acting saltpeter, potassium nitrate. This popular curing compound was known as “Prague Salt.”  (Griffith Laboratories Worldwide, Inc.)

In Canada, Prague Salt was classified as food adulteration.  A progress report from the Canadian department of agriculture in 1925 lists the fact that “one sample of Prague salt” was tested and it was found to contain “5.87 % of potassium nitrite.” It calls it an adulteration.  (Progress Report for the Years  Canada. Dept. of Agriculture. Division of Chemistry, 1912)

In 1925 in the USA however, the fortunes of nitrite seem to change overnight.  If the courts continue to find against the use of an ingredient in food that is seen as a food adulteration, the easiest way to solve the problem is to change the law. In Oct 1925 the American Bureau of Animal Industries legalised the use of sodium nitrite as a curing agent for meat. In December of the same year (1925) the Institute of American Meat Packers document appeared which we already referenced, “created by the large packing plants in Chicago”, entitles “The use of sodium Nitrite in Curing Meats.”

A key player suddenly emerges onto the scene in the Griffith Laboratories, based in Chicago and very closely associated with the powerful meatpacking industry.  In that same year (1925) Hall was appointed as chief chemist by the Griffith Laboratories and Griffith started to import a mechanically mixed salt from Germany consisting of sodium nitrate, sodium nitrite and sodium chloride, which they called “Prague Salt.”

Probably the biggest of the powerful meat packers was the company created by Phil Armour.  You will recall that Phil was the mentor who set David de Villiers Graaff on his course of to build refrigerated railway cars to transport meat which became the backbone of his Anglo Boer War supply to the English forces.  More than any other company at that time, Armour’s reach was global.  It was said that Phil had an eye on developments in every part of the globe.  (The Saint Paul Daily Globe, 10 May 1896, p2) He passed away in 1901 (The Weekly Gazette, 9 Jan 1901), but the business empire and network that he created endured long enough to have been aware of developments in Prague in the 1910s and early ’20s.

Could one of the offers of employment that Ladislav received before 1926 have been from Armour or one of the other meatpackers in Chicago? Griffith Laboratories is formed in the year following the armistice in 1919.  This is the same year when the United Kingdom starts selling its sodium nitrite stockpile.  Two years later, even cheaper German and Norwegian sodium nitrite start arriving in the USA.  In response to this, import duties are levied against German sodium nitrite.

By April 1921, the import duties have been bolstered by a blanket embargo on importing sodium nitrite, except where a special permit is granted.  In 1924, the tariffs on sodium nitrite are increased by 50% to the maximum allowed level permitted under the law.  By this time, the use of sodium nitrite in curing brines were in all likelihood the norm in Chicago and the 50% increase would have impacted the bottom line of these companies.

Is it possible that by calling it the curing mix from Germany, Prague Salt (as opposed to German Salt or German Nitrites), did Griffith sidestep the import tariff and the required permit for importing sodium nitrite completely?  My thesis is that it is entirely possible. Even probable.  It probably misrepresented the content in Prague Powder (mislabeling) as well as misrepresenting the country of origin.

Just as a side note, I have over the years seen the same trend returning to the meat industry.  More and more companies pack their products without declaring the ingredients and apart from protecting the exact composition, I have seen many illegal ingredients going into meat curing in this way.

When Phil Armour passed away, his personal fortune was estimated at $50 000 000.  This is almost $1,500,000,000 in 2016.  So powerful were the packing companies that US anti-trust legislation was created to break these companies up.  The point is that big money was at stake and a big influence on parts of the American government.

Prague Salt

Is it possible that Prague Salt is no more than a clever name given to a curing brine?  Taking the full weight of the historical context of events in Prague, Germany, and the USA into account in the 1910s and 1920s; particularly the severe measures to keep German sodium nitrite out of the USA, with the last blow being dealt, in 1924; understanding the extreme pressure on the packing houses to deliver huge volumes of bacon faster, I seriously doubt it.  The name was probably deliberate in referring to the salt invented by Ladic in Prague but instead of giving him credit for the invention, it was in all likelihood a ruse to distract the attention from the real issue that German sodium nitrite was still coming into the USA despite a ban.

It seems that the name, Prague Salt was crafted to misrepresent the country of origin and possibly its real composition.  Importing salt was no problem.  There is a possibility, of course, based on the popularity of salt from Bohemia, and the fact that we know it was widely exported, including to Germany, that the original mix done in Germany, could even have contained salt from Prague, mixed with German sodium nitrites. Whether this was so or not, the name had enough of a basis in reality in Ladislav Nachtmullner, Praganda and the famous salts from Prague to get it past the customs officers at the American harbours and into the meatpacking plants of Chicago and later, around the world. The fact that it was tested in Canada and found to contain nitrite shows that this was not declared at borders, at least in one of the events of the import into Canada and even though this does not prove that it was done in the US also, it builds the case for the theory that it was imported into the US without a disclosure of its nitrite content at the borders.

Prof. Julius Hortvet, in his address in Pittsburgh, had these prophetic concluding remarks about the future of science in the food industry.  He said that “…it is imperative that the use of colouring matter should be kept under intelligent control.  Regulations of the food industries will in future depend more than ever before on the results of scientific investigations, and the laboratory will become the dominant factor in the shaping of food standards and food laws.”  (American Food Journal; 1907)

The legal status of nitrites as food additive was clarified in 1925 through proper legislation, based on Prof. Hortvet’s principle of “intelligent control” when science decided the matter and it was taken out of the hands of “the court of popular opinion.” However, the involvement of the packing plants and Griffith in everything that happened in 1925 raises suspicion of collusion with the US government.

The real hero in the story is the master butcher from Prague who through practical application and the exact scientific inquiry that Prof Hortvet spoke about, developed the first commercially successful curing mix, Praganda.  Unknowingly, he became the central figure in the saga about the naming of  Prague Powder and the worldwide phenomena of the direct addition of nitrites to curing brines.

Finally, there is Griffith Laboratories.  The way in which Prague Salt came into the USA was probably not above board.  They did, however, became pivotal around the world in making the direct addition of sodium nitrite through Prague Salt and later, Prague Powder a worldwide phenomenon.  If Ladislav was the messiah to the bacon industry with his nitrite containing curing mix, Griffith was his St. Paul, the evangelist to the gentiles! 

They preached the gospel of a new curing brine that swept the world.  So much so that today, it is universally used as the curing brine of choice and only a handful of artisan curing operations still use the tank curing method.  One of the largest operations in the world that retain this as at least one of their curing methods is Direct Table Foods from Bury St Edmunds, United Kingdom.

This was one of the most significant developments in the world of bacon curing.  As I have said many times before, understanding the limitations and the mechanics of the system is very important to the modern-day curing plant manager.  The tale of nitrite and how sodium nitrite became the curing salt of choice is riveting and involves some of the most important names in scientific history.

Well, my son, there you have it.  A story of suspense, intrigue, and risk-taking!  Remarkable!  I am excited to see you soon during your upcoming vacation.  There is a chance that Lauren may come home over the same time.  What a blessing that will be to Minette and me.  Liam is finishing school this year as Luan is going to Grade 1.  We can all go up in Kirstenbosch with Skeleton Gorge one morning and spend the day in the Botanical Gardens in Cape Town.  I can not wait to see you!

Lots of love from Cape Town,

Dad and Minette.


Further Reading

Difference between Fresh Cured and Cooked Cured Colour of Meat.

Mechanisms of meat curing – the important nitrogen compounds

Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour.

The Naming of Prague Salt

Tank Curing Came from Ireland

The Mother Brine

Concerning the direct addition of nitrite to curing brine

Concerning Chemical Synthesis and Food Additives


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Notes

1. The colour changes in meat.

The meat colour generally “changes” (either red, purple or brown), based on how many electrons are spinning around the iron atom which is part of myoglobin. Nitric oxide stabilizes or fixes the myoglobin colour through a reversible chemical bond. It does not colours the meat. (Pegg, B. R. and Shahidi, F.; 2000: 23 – 45) This is an important point to remember because, in the consideration of the use of nitrite in meat, nitrite can not be viewed as a meat colourant.

2. Rate of reaction.

The reaction of nitrite in meat is slow, in part due to the very small quantity used in the curing brine. The rate of reaction, as always, depends on the concentration of the reactants, the pH and temperature.

3. Nitrosating species from nitrous acid.
“The first step in the reaction sequence beginning with nitrous acid is the generation of either a nitrosating species or the neutral radical nitric oxide (NO).” (Sebranek, J. and Fox, J. B. Jn.. 1985)

The following list gives the relative reactivities of various nitrosating species, species 1 being the strongest and species 5 being the weakest.

Species 1:

NO smoke

Source: “From smoke which has many other phenolic compounds”

Species 2:

CodeCogsEqn (55)

Source: From curing salt

Species 3:

CodeCogsEqn (57)

Source: Found in the air.

Species 4:

CodeCogsEqn (22)

Source: Nitrous acid anhydride

Species 5:

Nitrose derivatives of citrate, acetate, sulphate, phosphate.

Sources: Cure ingredients, weakly reactive under certain conditions.

I excluded those found under very acidic conditions. (Comparison by Sebranek, J. and Fox, J. B. Jn.. 1985)

4. The term “nitrite”

“The term nitrite is used generically to denote both the anion, CodeCogsEqn (17), and the neutral nitrous acid CodeCogsEqn (19) , but it is the latter which forms nitrosating compounds.” (Comparison by Sebranek, J. and Fox, J. B. Jn.. 1985)

5. Reducing agents in the meat system.

One such mechanism for the conversion of “nitrite to nitric oxide in meat is by oxidation of myoglobin to metmyoglobin (brown coloured meat; Fe3+). This oxidation-reduction coupling produces both nitric oxide and metmyoglobin. It has been suggested by Kim et al. (2006) that metmyoglobin can be converted back to deoxymyoglobin through metmyoglobin reducing activity (MRA), a reaction facilitated by lactate. It is the enzyme activity of LDH that helps convert lactate to pyruvate and produce more NADH. Hendgen-Cotta et al. (2008) suggested that deoxymyoglobin can convert nitrite to nitric oxide and the generation of more deoxymyoglobin is likely to result in more nitric oxide (NO) from nitrite and less residual nitrite.” (Mcclure, B. N.; 2009: 28)

Several specific biochemical reducing systems have been the subject of intense investigation as far as their importance in the development of cured meat colour is concerned.

“Endogenous compounds such as cysteine, reduced nicotinamide adenine dinucleotide, cytochromes, and quinones are capable of acting as reductants for NOMb formation (Fox 1987). These reductants form nitroso-reductant intermediates with NO and then release the NO to Mb, forming a NOmetMb complex that is then reduced to NOMb. In model systems, the rate-limiting step in the production of NOMb was the release of NO from the reductant-NO complex (Fox and Ackerman 1968). Several researchers have investigated the effects of endogenous muscle metabolites including peptides, amino acids, and carbohydrates on the formation of NOMb. Tinbergen (1974) concluded that low-molecular-weight peptides such as glutathione and amino acids with free sulfhydryl groups were responsible for the reduction of nitrite to NO, which is subsequently complexed with Mb to produce NOMb. Similar work by Ando (1974) also suggested that glutathione and glutamate are involved in cured-meat colour formation. Depletion of these compounds in meat via oxidation occurs with time, but reductants such as sodium ascorbate or erythorbate are added to nitrite-cured meats before processing to ensure good colour development (Alley et al. 1992) The role of reductants in heme-pigment chemistry is somewhat ambiguous, but they can promote oxidation and even ring rupture under certain conditions. Thus to form cured meat pigment, two reduction steps are necessary. The first reduction of nitrite to NO and the second is conversion of NOmetMB to NOMb.” (Pegg, B. R., and Shahidi, F.; 2000: 44, 45)

6. Sugar as reducing agent.

“Sugars itself does not reduce dinitrogen trioxide in the way that ascorbate or erythorbate does, but it contributes to “maintaining acid and reducing conditions favorable” for the formation of nitric oxide.” (Kraybill, H. R.. 2009)”Under certain conditions reducing sugars are more effective than nonreducing sugars, but this difference is not due to the reducing sugar itself. The exact mechanism of the action of the sugars is not known. It may be dependent upon their utilization by microorganisms or the enzymatic systems of the meat tissues.” (Kraybill, H. R.. 2009)

7. Ascorbate or erythorbate supplements sugar.

An excellent reducing agent was discovered in the 1920s when ascorbate was isolated. As early as 1927, two German chemists, J. Tillmans and P. Hirsch (1927) observed that there is a correlation between the reducing capacity of animal tissue and their vitamin C content. (Concerning the Discovery of Ascorbate) . It reacts so aggressively (effectively) with nitrite, that a less effective, but more manageable cousin (an isomer of ascorbate), erythorbate turned out to be the most practical to use in curing brines along with nitrite and salt.

Ascorbate (vitamin C) reacts so aggressively (effectively) with nitrite, that a less effective, but more manageable cousin (an isomer of ascorbate), erythorbate turned out to be the most practical to use in curing brines along with nitrite and salt.

The old curing brines of the 1800s consisting of saltpeter (nitrate), sugar (create reducing conditions) (6) and salt are, therefore, equivalent to the current curing brines of nitrite (being added directly), erythorbate (reducing agent) and salt. The same general functionality at vastly reduced curing time.

Today, nitrate is still being added to many curing brines as a reservoir for future nitrite as bacteria continue to change nitrate into nitrite. This bolsters the residual nitrite levels in cured meat which is important since it was found that nitrite has a unique anti-microbial function in cured meat, in addition to its function of fixing the cured colour and contributing to the cured taste. It is unique in the sense that it is the most effective chemical control against a highly lethal pathogen, clostridium botulinum. (Concerning Nitrate and Nitrite’s antimicrobial efficacy – chronology of scientific inquiry)

Table salt remains the most important curing agent, but salt alone will not give the cured colour or taste and will not, on its own, be effective against clostridium botulinum. Sugar is still being used in many brines today, mostly to enrich the taste profile and to create browning during frying, especially in bacon. Its contribution to reducing conditions is now secondary and since the addition of ascorbate or erythorbate. Saltpeter has been replaced by sodium nitrite.

8. Nitrite as medicine.

“The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris in 1867, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action.” BACK TO POST

9. Azo dye and textile colouring in 1895.

“Dyeing with Diazotised Dyestuffs

All the diazotised dyestuffs belong to the substantive group, and therefore, all that has been said with regard to these dyestuffs and their manner of application applies to the former also. In the majority of instances, however, the dyeings obtained directly are not sufficiently fast to be usable in that condition. Nevertheless, they can be converted into fast dyeings — provided the dyestuff contains free amino groups — by diazotising, followed by developing or coupling. The chemical reactions and method of procedure are just the sam.e as in the case of cotton.

In practice, the diazotising is effected in the following manner : —

The dyed and rinsed silk is entered at once into the cold diazotising bath and is worked about constantly for fifteen to thirty minutes. For every 100 parts of silk, the bath contains 3 parts of sodium nitrite dissolved in 1500-2000 parts of cold water, 8-10 parts of crude hydrochloric acid (20° Be.) being added. The operation must be conducted in wooden vats, metal vessels or fittings (lead excepted) being unsuitable. At one time, ice was used for cooling during the process, but this has been given up in favour of water at ordinary temperature, and in some cases, e. g. diazo indigo blue, the bath may be allowed to rise to 20-30° C. As a rule, the diazotisation will be complete in fifteen minutes, though some dyestuffs take longer and have to be left in the nitrite bath for half an hour. The goods are centrifuged or squeezed, contact with metal being avoided. A lead-lined hydro-extractor may be used, or else the goods must be wrapped in packing-cloth.

The intermediate diazo compound formed on the fiber is very unstable and sensitive to light, especially direct sunlight. The operation must therefore be carried on in a shady room, and care be taken to prevent any part of the diazotised goods from getting dry, or streaks and spots will be formed in the coupling stage. The diazotised material is rinsed and then immediately entered into the developing bath. The nitrite baths will keep for a considerable time and can be freshened up for use by the addition of one-third the original amounts of nitrite and acid. During the whole process the bath should smell strongly of nitrous acid. In the case of light shades, the bath may be weaker in nitrite and acid.” (Ganswindt, A; 1895: 98, 99) BACK TO POST

10. The Professional Career of Ladic

After his apprenticeship, he worked in several factories in Praha (Kracik, Beranek, Ugge-Sitanc and Miskovsky) as an assistant. His first work as a specialist in his field was with A. Chmel, Fr. Hlousek in Paha, Fr. Strnad in Lazne Luhacovice, and later in Germany, at the factories of Josef Sereda, Fr. Seidl, Zemka and Leopold Fisher in Berlin.

He worked as a “cellar man” at Josef Cifka, Vaclav Miskovsky in Praha, Kat. Rabus & Son in Zagreb, Jugoslavia,

Later he worked as a Foreman (Workman Leader) for the companies, Fr. Maly, Vacl. Havrda, A. Kadlec in Praha and Alexander Brero, Hard a/Bodensee Vorarlbersko and, in the end, he worked as a “Quick Production Specialist” for the export of hams for Carl Jorn A.-., Hamburg, Germany, Herrmann Spier, Elberfeld, Westfalsko, Karl Frank, Urach b/Stuttgart, Wurttemberg, A. Brero & Co, St. Margrethen, Switzerland.

11. The first War Raw Materials Department (KRA) in Germany was created (KRA) in mid-August 1914,  as suggested by Walther Rathenau.   (Vaupel, E.  2014:  462)  Walter was the son of the founder of AEG and “one of the few German industrialists who realized that governmental direction of the nation’s economic resources would be necessary for victory, Rathenau convinced the government of the need for a War Raw Materials Department in the War Ministry. As its head from August 1914 to the spring of 1915, he ensured the conservation and distribution of raw materials essential to the war effort. He thus played a crucial part in Germany’s efforts to maintain its economic production in the face of the tightening British naval blockade.”


References:

Ladislav Nachmüllner vulgo Praganda. Nachmüllnerová, Eva, Editor, 2000, Translated by Monica Volcko

1907. American Food Journal. Volume 2.Chicago Daily Tribune, 7 Jul 1910, Thu. P15Chicago Sunday Tribune, Nov 10, 1907, The Cincinnati Enquirer ( Cincinnati, Ohio), 27 September 1923. Page 14

The Detroit Free Press (Detroit, Michigan) reported, 14 Jan 1921, p 16Detroit Free Press, Detroit, Michigan, 11 June 1921, p4

Detroit Free Press, 22 Apr 1921, Fri, Page 18Ernst, FA. 1928. Fixation of Atmospheric Nitrogen. D van Nostrand, Inc.http://www.fda.gov/RegulatoryInformation/Legislation/ucm148690.htm

Gamgee, A. 1867 – 1868. Researches on the Blood. On the Action of Nitrites on the Blood. Proceedings of the Royal Society of London. Vol. 16 (1867 – 1868), pp. 339-342. Published by: Royal Society.

Ganswindt, A. 1895. Dyeing. Silk, Mixed silk fabrics and artificial silks. Translated from German by Charles Salter. Scott, Greenwood & Son.Griffith Laboratories Worldwide, Inc. official company documents.

Hoagland, Ralph. 1914. Coloring matter of raw and cooked salted meats. United States Department of Agriculture. National Agricultural Library. Digital Collections.

Hiemstra-Kuperus, E. 2010. The Ashgate Companion to the History of Textile Workers, 1650–2000. Ashgate Publishing, Ltd.

The Indiana Gazette, 28 March 1924The Indianapolis News, 7 May 1924, Wed, Page 1

Jones, G. 1920. Nitrogen: Its Fixation, Its Uses in Peace and War. The Quarterly Journal of Economics. Vol. 34, No. 3 (May, 1920), pp. 391-431. Oxford University Press.

Kim-Shapiro, D. B., Schechter, A. N., Gladwin, M. T. 2006. Unraveling the Reactions of Nitric Oxide, Nitrite, and Hemoglobin in Physiology and Therapeutics. Arteriosclerosis, Thrombosis, and Vascular Biology. Published online before print January 19, 2006.

Kraybill, H. R.. 2009. Sugar and Other Carbohydrates in Meat Processing. American Meat Institute Foundation, and Department of Biochemistry, The University of Chicago, Chicago, Ill. USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY. Chapter 11, pp 83–88. Advances in Chemistry, Vol. 12. Publication Date (Print): July 22, 2009 . 1955

Ladislav Nachmüllner vulgo Praganda Nachmüllnerová, Eva. OSSIS,2000Mcclure, B. N.; 2009.

The effect of lactate on nitrite in a cured meat system. Iowa State University.Packer, L. 1996. Nitric Oxide, Part 1. Academic Press.

Pegg, B. R. and Shahidi, F. 2000. Nitrite Curing of Meat. Food & Nutrition Press, Inc.

Polenske. E.. 1891 Works from the Imperial Health office, Volume 7, Springer, Berlin, S. 471-474Progress Report for the Years Canada. Dept. of Agriculture. Division of Chemistry.

Sebranek, J. and Fox, J. B. Jn.. 1985. A review of nitrite and chloride chemistry: Interactions and implications for cured meats. J. Sci. Food. Agric. 1985, 36, 1169 – 1182.

The Saint Paul Daily Globe, 10 May 1896,

http://saintpaulhistorical.com/items/show/183

http://www.stm-ke.sk/index.php/en/detached-expositions/solivar-near-presov

Scott, E. Kilburn. 1923. “NITRATES AND AMMONIA FROM ATMOSPHERIC NITROGEN. Lecture I”.

Journal of the Royal Society of Arts 71 (3702). Royal Society for the Encouragement of Arts, Manufactures and Commerce: 859–76.

http://www.jstor.org/stable/41356346.

Sullivan, G. A., 2011. “Naturally cured meats: Quality, safety, and chemistry”. Graduate Theses and Dissertations. Paper 12208.Sydney Morning Herald on 1 Mar 1870 (p4)

The Times, London, Greater London, England, 1 May 1919, Page 18Toldr, F.. 2010.

Handbook of Meat Processing. John Wiley & Sons Inc.Turmock, D.. 1989.

Eastern Europe: A Historical Geography 1815-1945.

RoutledgeVaughn E. Nossaman, Bobby D. Nossaman, Philip J. Kadowitz; Cardiol Rev. Author manuscript; available in PMC 2011 July 1; Published in final edited form as: Cardiol Rev. 2010 Jul–Aug; 18(4): 190–197. 10.1097/CRD.0b013e3181c8e14a

The Watchman and Southron, 19 Feb 1921, Sat, First Edition, page 3

The Weekly Gazette, 9 Jan 1901, Wed, Page 3

Webb, H. W.. 1923. Absorption of Nitrous Gasses. Edward Arnolds & Co, London.

Zofia Gołąb-Meyer Marian. 2006. Albert Einstein and Ignacy Mościcki’s, Patent Application. Smoluchowski Institute of Physics, Jagellonian University, Cracow, PolandImages

Image

1: Old Prague: Old Prague Logansport Pharos-Tribune Sat Oct 19, 1895Image

2: Ladislav Nachmüllner from Ladislav Nachmüllner vulgo Praganda Nachmüllnerová, Eva. OSSIS, 2000.Image

3: Ladislav Nachmüllner from Ladislav Nachmüllner vulgo Praganda Nachmüllnerová, Eva. OSSIS, 2000.Image

4: Sodium nitrite, photos by Prof Duchon.Image

5: Germany. http://theintersectionist.com/wp-content/uploads/2012/05/austerity-for-middle-class-meat-market.jpg

Image 6 and 7: Notice of sale by UK government: The Times, 1 May 1919, Thu, Page 18Image 8: Union Stock Yard, Chicago. The Modern Packing House. 1905, 1921. Nickerson & Collins.

Chapter 11.03: The Direct Addition of Nitrites to Curing Brines – the Master Butcher from Prague

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


The Direct Addition of Nitrites to Curing Brines – the Master Butcher from Prague

September 1959

Dear Tristan,

Prague 1
Prague, photo by Dawie Hyman

I received your previous mail with great excitement. Your account of Henry Hudson’s exploration around the New York area, what became known as Hudson Bay and the Hudson River is riveting! I am so glad you go to exhibitions such as these! It broadens our horizons ! You know that we get to read newspapers from around the world in our Cape Town library. Last Monday I went into the city and spent the day at the library and the archives. I made this clipping from the Troy Record for you advertising the exhibition you visited in Amsterdam.

The_Troy_Record_Fri__Mar_27__1959_
From the Troy Record, Troy, New York, 27 March 1959.

The story is epic. How an Englishman was employed by the Dutch East Indian Company to find the rumoured northeast passage to Cathay via a route above the arctic circle. He landed in North America in 1609 where he explored the regions around New York looking for a Northwest Passage. His exploits became the basis for a Dutch Colony that was later established here and the Hudson River was named after him.

He was back in 1611, this time on behalf of the English East Indian Company but his voyage ended in a mutiny by his crew when, after a long winter, they were eager to return to Europe when Hudson wanted to press on with his trip. In the end, Hudson, his teenage son John, and seven crewmen (all men who were either sick and infirm or loyal to Hudson) were forced into a small shallop (a name used for several types of boats and small ships) and left behind. The small vessel tried to keep up with the large ship but they hoisted another sail and left the small boat behind. Hudson, his son and the others left behind were never seen again.

It can, on the one hand not imagine a more desperate situation than to be left behind with your son when he will either see his dad dying at the hand of hostile locals or by the challenges of nature. If the son did not see his father suffering these, it was surely the father who saw his son dying. Yet, I can not help but notice that he took his son with him on his exploration! That reminds me us!

The events transpired in the 1600s which is where I want to pick up the story of the art of bacon. I am very thankful that I am able, through the technology of writing, drawings, and pictures, to share my adventure with you and your sister. I enjoy the fact that my voyage of discovery involves all the senses. It challenges and engages my entire being, mind, and soul! The quest is not only bacon but life itself and the crown of life most certainly, is not the places I visited and the many things I learned, but Minette! How thankful am I that we walk this amazing path together and with you guys!

Meat Curing: 1600 to 1910

Prague 2
Prague Breakfast by Dawie Hyman

Before the 1600s meat preservation was done with salt only. Colour in meat was important from antiquity because a reddish appearance denotes freshness. People looked for ways to manipulate meat colour for a long time, probably since meat was sold or traded. In the 1600s vegetable dyes were used to bolster colour. (The history of curing) A few people added a little bit of saltpeter (potassium nitrate) to the salt for “cured colour development.” This practice gained momentum from the year 1700. By 1750, the trend turned into the norm, being practiced almost universally as salpeter became universally available and the quality and purity improved. During the 1800s sugar was added to the mix. This, with the exception of ascorbic acid and phosphates that have been added since the mid-1900s, is very much the same process as we follow today. (Ladislav NACHMÜLLNER vs The Griffith Laboratories)

On 7 May 1868, Dr. Arthur Gamgee from the University of Edinburgh, brother of the famous veterinarian, Professor John Gamgee (who contributed to the attempt to find ways to preserve whole carcasses during a voyage between Australia and Britain), published a groundbreaking article entitled, “On the action of nitrites on the blood.” He observed the colour change brought about by nitrite. He wrote, “The addition of … nitrites to blood … causes the red colour to return…” (Gamgee, A; 1867 – 1868; Vol. 16, 339-342) Over the next 30 years, it would be discovered that it is indeed nitrites responsible for curing and not the nitrates added as saltpeter.

It fell upon a German researcher, Dr. Ed Polenske (1849-1911), working for the Imperial Health Office in Germany, to make the first discovery that would lead to a full understanding of the curing action. He prepared a brine to cure meat and used only salt and saltpeter (nitrates). When he tested it a week later, it tested positive for nitrites. (Polenske. E. 1891)

The question is where did the nitrites come from if he did not add it to the brine, to begin with. He correctly speculated that this was due to nitrate being converted by microbial action into nitrite. He published in 1891. (Polenske. E. 1891)
Karl Bernhard Lehmann and Karl Kißkalt discovered in 1899 that nitrite is responsible for the reddish color of dry-cured meat. It was John Scott Haldane who showed in a 1901 article that the cured meat colour is due to a nitrosylheme complex. (Concerning the direct addition of nitrite to curing brine) (Hoagland, Ralph. 1914)[1] The heme part of the meat protein is where the colour is generated through the presence of an Fe ion and nitrolsyl refers to a non-organic compounds containing the NO group. In the protein, nitric oxide is bound to the Fe ion through the nitrogen atom. Therefore the term, nitrosylheme complex.

The change of nitrate into nitrite through bacterial action takes weeks. If a salt, like sodium nitrite, is used instead of saltpeter, curing is accomplished in days or even hours (if a heating step is applied to the meat before it is smoked).

The only aspect in curing that is time-consuming is however not the bacterial reduction of nitrates to nitrites. The change from nitrite into a form that reacts with the meat protein and produce the nitric oxide coupling with the Fe ion is also not instantaneous. The rate of reaction is slow.[2] It is not like mixing sugar into coffee. An analogy is if you put sugar in your coffee and have to wait twelve hours and reheat it in the microwave before you can taste sweetness.

When the brine enters the meat, the anion CodeCogsEqn (17) is formed and a very small amount of nitrite (less than 1% of the total nitrite) forms the neutral nitrous acid (CodeCogsEqn (19)). It is nitrous acid that is responsible for the formation of nitrosating compounds which is the ultimate reaction of joining nitric oxide to an organic compound, in this case, the myoglobin protein (resulting in a nitroso derivative). (Sebranek, J. and Fox, J. B. Jn.. 1985)

The first step in the reaction sequence of creating such a link between myoglobin and nitric oxide is the formation of nitrous acid (HNO2). From nitrous acid, the neutral radical, nitric oxide is formed directly as well as a variety of nitrosating species or molecules that create such a nitrite-oxygen pair of atoms to link to an organic structure like a protein. [3] [4] (Sebranek, J. and Fox, J. B. Jn.. 1985)

This reaction takes time and its rate is dependent on the pH of the meat it is injected into, the temperature of the meat and the brine and the concentration of nitrite. Curing then happens when the nitric oxide reacts with iron which is part of the meat proteins, myoglobin. [1]

The concentration of nitrous acid is very low in meats. This means that the potential for nitrite to change into nitric oxide to react with the meat protein is very low. In general, nitrite is readily reduced by endogenous reductants in the meat to form nitric oxide. (Toldr, F.; 2010: 180) [5] The reduction of nitrous acid can be sped up by adding a “reducing agent” to the brine mix. (Pegg, B. R. and Shahidi, F.; 2000: 39) (the presence of table salt also speeds up the conversion of nitric oxide, but this matter is for another article.

One such reducing agent, introduced to brine cures in the 1800s, is sugar. [6] Sugar was added originally to reduce the salty taste of the meat. Curers noticed that if sugar is added with saltpeter to the brine mix, the meat cures slightly faster and with better colour development. (The history of curing) In the 1920s, ascorbate or its isomer, erythorbate became the magical reducing agent [7], but this too is the subject for a future letter.

If saltpeter is used as principal curing ingredient, adding sugar favours the proliferation of bacteria that reduces nitrate to nitrite. It, therefore, speeds up the curing process. Better colour development is due to the action of reducing sugars (such as brown sugar) to create a reducing environment in the meat which encourages the reduction of nitrous acid to nitric oxide (Kim-Shapiro, D. B. et al. 2006). [6] (The history of curing)

Investigating Two Sources of Nitrite’s

Prague 3
Prague Supper by Dawie Hyman

This was then the understanding of meat curing by the beginning of the 1900s. Scientists knew that adding nitrite directly to the meat would dramatically speed up the curing process, but working out how to do it and navigating through the complex maze of public perception and legal restraints would be another matter altogether.

The Irish and later the Danes took the development where nitrites are directly applied to curing, in one very particular direction. They invented the “mother brine” cure. The concept of re-using the old brine and meat juices was a well-known practice in many regions of the world from early on. Butchers worked out that it speeds up curing, even long before the term nitrite was coined. It was the Irish who invented a system to exploit the mother-brine approach on an industrial scale. The Danes got the technology from Ireland and I, after studying under Uncle Jeppe and Andreas in Denmark taught the system to John Harris in Calne. They called it tank curing which is a method of allowing bacteria to reduce saltpeter to nitrites and the nitrites to be added back into bacon brine after it was boiled to kill the bacteria. The net result is that nitrites were produced through bacterial means and the nitrites were used to cure the meat much quicker than could ever be done with saltpeter alone. (The Mother Brine and C & T Harris and their Wiltshire bacon cure)

There was, however another readily available source of nitrites which became the focal point of meat curers in Germany, Austria, Hungary and in the USA. Nitrites were already being used in a large, industrial process since the end of the 1800s in the form of sodium nitrite. This made it generally available.

Sodium nitrite was used in the production of azo dyes. It was available in every country and city where there was a large dye industry. This was part of the new and booming new industry of coal-tar dyes. The late 1800s and early 1900s was the birth of the age of chemistry and chemical synthesis, a development that directly resulted from the dye industry. (Concerning Chemical Synthesis and Food Additives)

There were early scientific flirtations with the use of sodium nitrite in meat. A laboratory in Germany, founded by C. R. Fresenius, records in 1848 experiment with sodium nitrite to preserve meat. (Ladislav NACHMÜLLNER vs The Griffith Laboratories)

An article appeared in the Sydney Morning Herald on 1 March 1870 where it lists the methods of preserving canned meat in use at that time. Included in the list of “antiseptic agents” are “sulfurous and nitrous acids, sulphites and nitrite. (It also lists sodium and “other substances having a special affinity for oxygen.”) It was explained that “these agents are not applied to meat itself, but are used simply to absorb oxygen unavoidably left within the tins and pores of the meat.” As far as the preservation of fresh meat is concerned, the world saw it as a race between the use of chemicals or cold. (Sydney Morning Herald, 1 March 1870, p4)

PRAGUE 1800 – 1920 – Food innovation, industrial leadership and the availability of nitrite

old-prague-logansport_pharos_tribune_sat__oct_19__1895_Prague, Logansport Pharos-Tribune, 19 Oct. 1895

Germany’s neighbor and ally in World War One, the Austro-Hungarian Empire with the key cities of Prague, Vienna, and Budapest, in the late 1800s and early 1900s led the world in many respects in matters pertaining to science and technology.  In Bohemia and regions surrounding Prague, the industries were leading Europe in innovation.  (Turmock, D.;1989: 40)  It was reported that in many respects, the industry  in this region surpassed Germany.

A huge textile industry developed in Vienna.  In Prague, cotton printing became the dominant industry with the accompanied dyes industry.  Bohemia, in general, had well-developed textile manufacturing.  (Hiemstra-Kuperus, E. 2010)  This means that by the early 1900s, sodium nitrite was available in and around the city of Prague.

Prague and surrounding areas were not just a consumer of chemicals.  The scientific and industrial environment was sophisticated and advanced and they produced many of the chemicals for their industry themselves, primarily in support of the textile printing industry.  The point is that we when we deal with the people in Prague, we are talking about people who understood chemistry (my personal experience is that this is still the case to this day).

D. Hirsch, for example, established his factory in Prague to “provide acid for calico printing in 1835.”  F. X. Brosche supplied  printing inks, paint, and pharmaceuticals.  The first major chemicals producer in the area was Johann David (J. D.) Starck had a sulfuric acid plant near Zwittau (now Svitavy in the Czech Republic), 183km to the east of from Prague, in 1810.

Between 1810 and 1850, J. D. Starck expanded into a multi-plant operation manufacturing a variety of products including phosphates at Kaznau (now Kosnejov, in the Czech Republic), 109km South West of Prague.   He was big enough to own his own source of coal from the Falknov (Sokolov) basin.   (Turmock, D.;1989:  39)  It all supports a picture of sodium nitrite being readily available in Prague as part of the chemicals associated with the dying and textile printing industry. [9]  More than that, the Bohemian people proofed to be innovative and capable in matters pertaining to chemistry.

At the end of the 1800 and beginning of the 1900s, Prague was a fertile breeding ground for industrial and food innovations.  A case in point is the phenomenal success of Pilsner named after the city of Pilsen (Plzen).  The innovation was the application of steam power to the production of chilled lager.  It was an important improvement in the old processes and helped the town of Pilsen to become one of the great European beer producers. (Turmock, D.;1989: 40)

Another Bohemian innovation was the invention of the sugar beet refining process through diffusion to produce refined sugar.  “The diffusion process was discovered in Seelowitz  (Zidlochovice) in Moravia by J. Robert, the son of the founder of the first sugar beer factory in the Czech lands.”  Within a few years, 25 other factories converted to this process and sugar refining machines were being exported to Germany and France.  The Prague-based engineering firm of C. Danek (founded in 18540) was particularly successful.   (Turmock, D.;1989: 40)

The kingdom boasted the most sophisticated food industry with a very strong scientific backing from the local academia in Prague.  Under their leadership, the first food code in industrialized Europe was created, the Codex Alimentarius Austriacus, which is the basis for international food legislation to this day.   (The Life and Times of Ladislav NACHMÜLLNER – The Codex Alimentarius Austriacus) It also became the first country in the world to specifically allow the use of sodium nitrite in food, before Germany and the US.

Not just was Prague and the Bohemian people leading the world in food innovation and food science and chemistry, but the existence of large food industries created an environment where other food industries would benefit, for example, the meat industry.  (Turmock, D.;1989: 39, 40)

The Master Butcher from Prague

The ether around Prague and the Bohemian people was right for a company or an individual to step forward and take up the challenge to work out the details of how to use sodium nitrite directly in meat curing.

Ladic

Into this advanced and scientifically and industrially mature environment, Ladislav Nachmullner was born on 2 April 1896. (Eva’s Beloved Dad) In 1912, the Bohemian boy, Ladic (Ladislav) NACHMÜLLNER was 16 years old. His dad tragically burned to death four years earlier, in 1908, when his clothes caught fire in his home. His mother had just passed away from tuberculosis and as the oldest child, the responsibility fell on him to care for his siblings.

Ladic got an opportunity to learn the art of meat curing to provide for his siblings in a land where chemistry was well understood, salts were of high quality, sodium nitrite was widely available and there was an appetite for and a culture of innovation in food production. The kingdom boasted the most sophisticated food industry with a very strong scientific backing from the local academia in Prague. Under their leadership, the first food code in industrialized Europe was created, the Codex Alimentarius Austriacus, which is the basis for international food legislation to this day. (The Life and Times of Ladislav NACHMÜLLNER – The Codex Alimentarius Austriacus) More importantly for my quest to understand bacon chemistry, it was the first country in the world to specifically allow the use of sodium nitrite in food, before Germany and the US. This set the stage for a remarkable development.

Ladic knew sodium nitrite well from his father who was a glassmaker. Even as a boy, he would have been exposed to it. His father encouraged him never to enter the glassmaking profession and he instead chose curing as a way to provide for his siblings. He was taught the art of curing by a well-known butcher, Josef Pazderky from Praha, almost 600km from Prague. He was an unusually gifted young man who learned fast and an illustrious career followed.[10] At the young age of 19, he invented Praganda, which would become the most successful curing brine of its day, containing sodium nitrite. This was the year 1915 when he also started writing his book on Praganda.

Ladic knew sodium nitrite well. The seemingly boring facts of the early experiments on curing and the confirmation through science that it was indeed nitrite responsible for curing and nit saltpeter was cutting edge technology of the time and the scientific findings were reported upon in many publications and newspapers of the time. Ladic must have been an unusually gifted and curious person and he read these reports with great attention, realising that he may have the answer to a much faster and more controlled way of accessing nitrite namely through the direct addition of sodium nitrite to the curing brine.

He wrote that he discovered the power of sodium nitrite through “modern-day professional and scientific investigation.” He probably actively sought an application of the work of Haldane. Ladic quotes the exact discovery that Haldane was credited for in 1901 that nitrite interacts with the meat’s “hemoglobin, which is changing to red nitro-oxy-haemoglobin.” This must have made a profound impression on him which explains why he never forgot it. If it was not him personally, it must have been his mentors in Prague who decided to start experimenting with sodium nitrite to develop a meat curing brine.

The “modern-day professional investigations” that he spoke off would have been the input of master butchers who were not primarily interested in a quicker process but in a better end product. Saltpeter is potassium nitrate. The butchers did not like it due to the slightly bitter taste of potassium. Butchers who used Ladic’s brine would later put signs in their shop windows that their meat is free of saltpeter.

Another point that Ladic specifically addressed in his nitrite-based brine is the use of as little nitrite as possible. This shows an advanced understanding of the chemistry or curing and an ability to apply this to his trade. The little nitrite would still cure the meat much faster than even the mild cured techniques as the Irish called it or the tank curing technology as the English referred to it.

His fame as curer spread and he received employment offers from more countries. He moved to Austria and then, Switzerland for the duration of the war. He received offers for management positions from all over Germany, France, England, Holland, Switzerland, Romania, Yugoslavia , Poland and as far afield as America and China.

Praganda

He says that he invented Praganda in 1915 (when he was 19 years old) and at a time when the use of nitrites in food was not legal in Germany.

We know that it was not legal in Germany before August 1914 when Walther Rathenau who created the War Raw Materials Department (Kriegsrohstoffabteilung or KRA) restricted the use of saltpeter to military purposes only and the use of nitrites in food was allowed. Germany again banned its use sometime during the war. The concession on sodium nitrite’s use in food was reversed after an accident in Leipzig where sodium nitrite was mistaken for table salt and 34 people died. (Concerning Nitrate and Nitrite’s antimicrobial efficacy – chronology of scientific inquiry) This must then have happened sometime in 1915.

The impression one gets from reading his life story through the writings of his daughter Eva, is that he probably learned the basics of nitrite curing early on and this “paid his way” on many travels through Europe. Along the way, he must have continued to refine and perfect his formulations and solve the many challenges of using such a potentially dangerous chemical. (For a detailed analysis of the technical challenged facing him and how he dealt with it, see Ladislav NACHMÜLLNER vs The Griffith Laboratories.)

His move to Switzerland for the remainder of World War One is of interest. In Switzerland, the Polish chemist, Prof. Mościcki of the University of Freiburg, invented a process to use atmospheric nitrogen to produce both nitric and nitrous acid (US patent US1097870) in 1901 through the use of an electric arc in a closed container. (cesa-project.eu)

In 1910, a factory opened in Switzerland, Chippis, in Wallis canton, where the world’s first nitrous acid was produced using Prof. Mościcki’s electric arc process. (cesa-project.eu) This means that a factory producing nitrite was in operation in the same country where Ladislav lived, during the war.

It is equally important that Prof. Mościcki opened another factory in Poland during the War, the Azot nitrogen factory near Jaworzno. (cesa-project.eu) Jaworzno is less than 460km from Prague.

From the evidence of his life, handed down to us by his daughter, Eva, he returned to Prague from Switzerland in 1929 and set up his first outlet where he sold Pragnada and ham moulds which he invented. It makes Prague the center of the development to add sodium nitrite directly to meat, other than canned meat.

The Salts from Prague

The history of Ladislav Nachmuller not only points to the first commercial curing brine containing nitrites but also to the use of pure salt from the regions surrounding Prague.  Using the correct salt was very important to Ladislav.  The area around Prague, like the neighbor to the north, Poland, was famous for the production of high-quality salt.  Ladislav procured salt from various mines, including from the salt producer, Solivary Prešov.  He gives the requirement for good salt as pure, clean, and “regular salt.”  This mine delivered on these requirements.

Mining at Solivary Prešov started as far back as the 13th century.  The salt was produced from “brines” (water saturated with a salt solution) where the water was evaporated.  First in pans and then in boiling rooms.  The final result was good quality NaCl (table salt) which has been popular among butchers in the area on account of its purity. (From private communication with the museum curator, Prof. Marek Duchoň)

Historical records inform us that the salt production exceeded local consumption, which points to the fact that the salt from Solivary Prešov was widely traded. The technology used in producing the salt was sophisticated. (http://www.stm-ke.sk/)

An interesting fact, relevant to our current discussion, is that the mine produced its own sodium nitrite since 1945.  It falls outside our time of interest and the production has since been discontinued, but the fact that producing sodium nitrite was fairly “widespread” and the technology, common in the area is fascinating.  (From private communication with the museum curator, Prof. Marek Duchoň)

prague saltSodium nitrite, produced at Solivary in 2007.

This is a key fact in piecing together why it was “natural” to call the sodium nitrite/ sodium chloride mix that Griffith imported into the USA, Salt from Prague.  The region was indeed famous for its salts.

A Fork in the Road

Ladislav’s invention was a fork in the road for nitrite technology. A new and “more direct” way of getting nitrite in the curing brine was developed. It is not surprising that it happened in the part of the world where nitrogen technology was best understood and where people were mesmerised through the opportunities created by the science of chemistry. It challenged the Irish mild cured system and the Danish and English Tank curing systems, as they called the mild cured process, by offering an even faster curing solution and one which is “safer”. The exact quantity of nitrites added can be much better controlled with this new system and when it comes to a substance such as nitrite that is poisonous in too high dosages, being able to control the amount of ingoing nitrite into the meat is very important.

Almost concurrent with Ladislav’s invention was events in Germany that brought about a wholesale conversion of German meat curers to this new and faster technology. Its getting time for Minette and my hike down to the promenade where we plan to do a 15km this afternoon. Caring for the body is just as important as caring for the mind.

I am glad you are getting out and seeing exhibitions in this great city where you find yourself! Learn as much as you can while you live in Amsterdam!

Lots of love from Cape Town,

Dad and Minette.


Further Reading

Difference between Fresh Cured and Cooked Cured Colour of Meat.

Mechanisms of meat curing – the important nitrogen compounds

Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour.

The Naming of Prague Salt

Tank Curing Came from Ireland

The Mother Brine


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Chapter 11.02: Fresh Meat Colour vs Cooked Cured Colour

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


Fresh Meat Colour vs Cooked Cured Colour

August 1959

Dear La’jie,

The_Evening_Sun_Thu__Dec_18__1958_
Advert from The Evening Sun, Hanover, Pennsylvania, 18 December 1958.

You are a very special person and the determination you showed in completing Biochemistry is tremendous! I am very thankful to Dawie who invited you to Los Angeles and got you an intern position at UTZ’s Meat Market! I remember the first booklet you did for our staff to explain the different hams we made at Woody’s!

Minette and I are excited to visit you one of these days. I wrote a letter to Tristan last month where I gave him an overview of the men and woman who shaped our understanding of the different reactions involved in meat curing. I also asked him to continue to add to my work even after I am gone so that it will be as “current’ as possible. You will have to do the bulk of the work since you have the understanding of the processes. Even after I returned to Cape Town in 1893 to help set up Woodys, the progress of our understanding of bacon did not stop. In fact, the opposite is true. It went full steam ahead!

The quest remained to understand it so that we are able to manipulate the process and produce the best bacon on earth! The two of you encouraged me for years to complete my work and document my journey, but with the pressure of a large bacon plant and me being responsible for production, I did not have any time. Now that both Oscar and I left the company, I have time to complete it and in my letters, I will continue with the story. One day you and Tristan can come together and take everything I wrote, compile it into a book and publish it.

When I was managing production at Woodys Consumer Brands (Pty) Ltd., I knew that I needed a detailed understanding of meat curing mechanisms to ensure that conditions exist to optimise cured colour development, limit bacterial growth and deliver good product flavour and taste. In short, understanding is required to make the best bacon on earth!

Here I set the historical context of the discoveries following Polenske by reviewing the 1914 landmark article by Hoagland. I focus on the importance of nitric oxide (NO) in cured colour development for both fresh and cooked cured meat.

The formation of cured meat colour takes place “by the reaction of nitrite with the natural meat pigment myoglobin to form dinitrosyl ferrochrome (DNFH). The pigment, which gives meat its characteristic cured-meat colour, is formed from the meat pigment myoglobin, which consists of an iron porphyrin complex, the heme group, attached to the protein globin. In the presence of nitrite, the bright red nitrosomyoglobin is formed, in which the H2O in the axial position on the heme iron is replaced by nitric oxide (NO). The NO is formed from nitrite by the natural reducing activity of the muscle tissue, which is accelerated by the addition of reductants such as ascorbic acid. In heat-processed cured meat, the globin has been split off to a heat-stable pink pigment, nitrosyl hemochromogen.” (Soltanizadeh, N., Kadivar, M.. 2012)

Ralph Hoagland

Chicago_Tribune_Sun__Jun_26__1927_
From the Chicago Tribune, Chicago, Illinois, 26 June 1927

This understanding of curing developed over many years with input from a variety of scientists. (The Fathers of Modern Meat Curing) One of these influential minds was Ralph Hoagland. His brilliance is seen in his academic work that shapes the meat curing industry. He had wide appeal in academia, industry and in the popular press. He contributed immensely to the developing sciences of nutrition and meat processing with a special interest in pork processing and pork nutrition.

He was the Senior Biochemist, Biochemie Division, Bureau of Animal Industry, United States Department of Agriculture in Chicago who was, at this time, one of the curing centers of the world along with Denmark and Calne, in the United Kingdom where the Harris operation started. He served as the department head of the Minnesota College of Agriculture (part of the University of Minnesota), appointed in 1909. The College of Agriculture later became the College of Biological Sciences. (http://cbs.umn.edu/ and The Bismarck Tribune, 1912)

In 1908 he published results obtained upon studying the action of saltpeter upon the colour of meat and “found that the value of this agent in the curing of meats depends upon its reduction to nitrites and nitric oxid, with the consequent production of NO-hemoglobin, to which compound the red color of salted meats is due.” He found that “saltpeter, as such, [had] no value as a flesh-color preservative.” (Hoagland, R. 1914) In 1914 he published, Colouring Matter of Raw and Cooked Salted Meat. Reviewing this article has three important objectives.

It shows what was understood by 1914 about meat curing and colour formation in particular. This has important implication for determining an accurate chronology of developments around the direct addition of nitrite to curing brines, such as the invention of Praganda in Prague in 1915 and later, the introduction of Prague Salt in Chicago (The Naming of Prague Salt) where Hoagland worked for a time. Secondly, it is a novel way for an introduction to meat curing mechanisms and shows the progression in our understanding. It also draws an important difference between the colour of fresh cured meat and cooked-cured meat. This is more important than it seems and highlites the importance of the heat step in bacon production.

In the notes, we interject the thoughts of Hoagland from 1914 with quotes on our current understanding by two of the leading scientists on the subject namely Ronald B. Pegg and Fereidoon Shahidi with quotes from their 2000 publication, Nitrite Curing of Meat. I briefly introduce these two scientists. (1)

THE COLOUR OF FRESH MEAT

Hoagland starts with the colour pigment of fresh meat, oxyhemoglobin. The word itself tells us what it is. “Oxy” is oxygen, connected to hem which is “hamatin” or the colouring group and “globin”, the protein. In Oxyhemoglobin, oxygen is connected to “hemoglobin, which is the protein molecule in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs.” (medicinenet)

Hoagland states that oxyhemoglobin, is “part of which is one of the constituents of the blood remaining in the tissues, while the remainder is a normal constituent of the muscles,” and “responsible for the red color of fresh lean meat, such as beef, pork, and mutton.” (Hoagland, R. 1914) Today we know that the colour of fresh lean meat is due to myoglobin, “the pigment in muscle that carries oxygen” (medicinenet), as opposed to protein in the blood.

I told Tristan in the letter to him that Hoagland and other older researchers of his day used hemoglobin and not myoglobin in their research. The reason for this was “a matter of convenience” and “a matter of necessity since myoglobin was not isolated and purified until 1932,” (Theorell, 1932) a full 18 years after Hoagland published. “In spite of the differences between hemoglobin and myoglobin, Urbain and Jensen (1940) considered the properties of hemoglobin and its derivatives sufficiently like those of myoglobin to allow the use of hemoglobin in studies of meat pigments.” (Cole, Morton Sylvan, 1961: 2)

Despite the fact that it is oxymyoglobin that is responsible for the bright red colour of fresh meat, we follow his arguments using oxyhemoglobin since the same mechanisms of colour development apply in both proteins. Pegg and Shahidi use myoglobin. (2)

The_Morning_Call_Sat__Mar_28__1931_
From the Morning Call, Allentown, Pennsylvania, 28 March 1931

THE COLOUR OF CURED MEAT

Generally, Hoagland saw the cured colour of meat as “the same color as the fresh meat.” (Hoagland, R. 1914) There is a difference between the cured colour of fresh meat and the cured colour of cured-cooked meat. He recognised this difference and said that “the red color is not destroyed on cooking, but rather it is intensified.” (Hoagland, R. 1914)

The nature of these two different kinds of colour is the subject of his article, “undertaken for the purpose of obtaining more complete information concerning the color of raw and cooked salted meats.” (Hoagland, R. 1914) It is therefore important to distinguish between the cured coulour and cured-cooked colour. This is important. The influential South African food scientist, Dr. Francois Mellett, developed a method of bacon curing that uses only the cured colour. He achieves this by curing and then freezing the meat. Freezing the meat should speed up the curing reaction as reagents are “forced together.” It is important to understand that the colour achieved in this way is different from the cured-cooked colour of conventional bacon. This is a novel invention with definate application, but understanding the different properties is very important since fresh cured meat and cooked-cured meat react differently to exposure to oxygen and light.

HISTORICAL BACKGROUND

In his historical summary, he lists the following developments that lead up to his own work.

-> Weiler and Riegel

“Weiler and Riegel (1897), in the examination of a number of samples of American sausages, obtained a red coloring matter on extracting the samples with alcohol and other solvents, which color they concluded to be in some manner due to the action of the salts used in curing upon the natural color of the meat. On account of similarity of spectra, this color was considered to be methemoglobin.” (Hoagland, R. 1914) (3)

-> Lehmann and Kisskalt

Lehmann (1899) identified nitrite as responsible for the red colour of meat and not nitrate. Kisskalt (1899) confirmed this and noted that “if the meat was first allowed to stand several days in contact with saltpeter and then boiled, the red color appeared” (Hoagland, R. 1914)

-> John Scott Haldane

John Scott Haldane (1901) made several important observations after an extensive study of the colour of cooked salted meat.

He is the first to attribute the colour of cooked salted meat “to the presence of the nitric oxide hemochromogen” (reduced hematin; Fe in reduced ferrous state, CodeCogsEqn (2); obtained by boiling oxymyoglobin/ oxyhemoglobin with a reducing agent). (Hoagland, R. 1914) He correctly concluded that nitric oxide hemochromogen is “resulting from the reduction of the coloring matter of the uncooked meat, nitric-oxid hemoglobin (NO-hemoglobin).” Hemochrome can be any of a number of complexes with the iron-porphyrin complex with one or two basic ligands (normally amines).

The terms nitric oxide hemochromogen, nytrosomyochrome, nitrosyl hemochrome, nitric oxide hemochrome, nitric oxide denatured globin hemochromogen, denatured globin nitric oxide ferrohemochrome, pigment of cured, heated meat, are all synonyms to refer to the same thing. (ICMSF; 1980: 140) Chromogen is a substance which can be easily converted into dye or other coloured compounds for example through oxidation. Since the 1940’s, the term “hemochrome” (hem and chrome) has been used instead of “hemochromogen” and “parahematin.” “The term “hemochromogen” is associated historically with an erroneous conception of one of these substances as the colored component of hemoglobin. These compounds are in any case not “chromogens” in the chemical sense, i.e., leuco compounds. The new term has the additional advantage of greater brevity.” (Lemberg, R. and Legge, J. W.; 1949: 165)

The_Birmingham_News_Fri__Jun_24__1927_
From the Birmingham News, Birmingham, Alabama, 24 June 1927

Linossier was the first to describe it and produced it by passing nitric oxide through hematin. (Haldane, J. S.. 1901) After careful study and observation, Haldene drew the following brilliant conclusions.

1. “The red colour of cooked salt meat is due to the presence of NO-haemochromogen.” (Haldane, J. S.. 1901)

2. “The NO-haemochromogen is produced by the decomposition by heat of NO-haemoglobin, to which the red colour of unsalted meat is due.” (Haldane, J. S.. 1901)

3. “The NO-haemoglobin is formed by the action of nitrite on haemoglobin in the absence of oxygen, and in presence of reducing agents.” (Haldane, J. S.. 1901)

4. “The nitrite is formed by reduction within the raw meat of the nitre used in salting.” (Haldane, J. S.. 1901)

5. “The nitrite is destroyed by prolonged cooking.” (Haldane, J. S.. 1901) (4)

He mentions Orlow (1903) who stated that “the red color of sausages is due to the action upon the color of the fresh meat of the nitrites resulting from the reduction of the saltpeter used in the process of manufacture.” (Hoagland, R. 1914)

“Humphrey Davy in 1812 (cited by Hermann, 1865) and Hoppe-Seyler (1864) noted the action of nitric oxid upon hemoglobin, but it appears that Hermann (1865) was the first to furnish us with much information as to the properties of this derivative of hemoglobin. He prepared NO-hemoglobin by first passing hydrogen through dog’s blood until spectroscopic examination showed that all of the oxyhemoglobin had been reduced to hemoglobin, then saturating the blood with pure nitric oxid prepared from copper and nitric acid, and finally again passing hydrogen through the blood to remove all traces of free nitric oxid.” (Hoagland, R. 1914)

By the time of publishing this article in 1914, he notes that NO-hemoglobin was mentioned very briefly in most of the texts on physiological or organic chemistry as being a hemoglobin derivative of “but little practical importance.” “Abderhalden (1911) and Cohnheim (1911), however, describe this compound quite fully.” (Hoagland, R. 1914)

Hoagland conducted several further experiments with NO-hemoglobin and outlined it in his 1914 paper.

COLOUR OF FRESH, CURED MEAT

He first deals with the Colour of Uncooked Salted Meats. “To a sample of finely ground fresh beef was added 0.2 percent of potassium nitrate, and the material was placed in a refrigerated room at a temperature of 34 deg F (1 deg C) for seven days. At the end of that period the meat had a bright-red color, but gave evidence of incipient putrefaction.” (Hoagland, R. 1914) He did the same by curing the meat with nitrite. He correctly concluded that the colour of fresh meat, cured with nitrite, is due to NO-hemoglobin. (Hoagland, R. 1914) (5)

Hoagland’s conclusion in his 1914 article is, however, limited to NO formation and its role in cured colour formation. He states that “the evidence is ample to show that the action of saltpeter in the curing of meats is primarily to cause the formation of NO-hemoglobin; but it is very possible that under certain conditions of manufacture or processing to which salted meats are subject, the NO-hemoglobin may undergo changes.”

fmc10
Ralph Hoagland at work.

COLOUR OF COOKED, CURED MEAT

“Haldane has shown that the red color of cooked salted meats is due to the presence of NO-hemochromogen, a reduction product of NO-hemoglobin to which the color of uncooked salted meats is due.”… “While Haldane’s work seems to show clearly that the color of cooked salted meats is due to NO-hemochromogen, it has seemed desirable to study the subject further and to determine especially if the NO-hemoglobin of uncooked meats be reduced to NO-hemochromogen under other conditions than by cooking. The fact that in the examination of certain uncooked salted meats a coloring matter had been obtained similar to NO-hemoglobin yet not possessing all of the properties of that compound, as has already been noted, led the writer to believe that the coloring matter of some uncooked salted meats might be due, in part at least, to NO-hemochromogen. NO-hemochromogen is but briefly mentioned in the literature. The compound is described by Linossier (1887), Haldane (1901), and by Abderhalden (1911).” (Hoagland, R. 1914)

“The structural relation between NO-hemoglobin and NO-hemochromogen is simple. NO-hemoglobin is a molecular combination of nitric oxid and hemoglobin—the latter compound consisting of the proteid group, globin, on one hand, and the coloring group, hemochromogen, on the other. NO-hemoglobin and NO-hemochromogen differ from each other simply in that one contains the proteid group, globin, while the other does not. Apparently, then, a method of treatment which would split off the globin group from NO-hemoglobin should result in the production of NO-hemochromogen, provided, of course, that the procedure did not in turn change or destroy the NO-hemochromogen produced. As has already been noted by Haldane, it was found that when a solution of NO-hemoglobin was heated to boiling, a brick-red precipitate formed, in contrast to the dark-brown precipitate which formed on heating a solution of oxyhemoglobin or of blood. The brick-red precipitate was filtered off and was then extracted with alcohol, which gave a lightred colored extract showing a spectrum with a fairly heavy band just at the right of the D line. This spectrum corresponds with that of NO-hemochromogen. On standing, the color of the extract faded rapidly.” (Hoagland, R. 1914)

“The evidence seems to show very clearly that the color of cooked salted meats is due to the NO-hemochromogen resulting from the reduction of the NO-hemoglobin of the raw salted meats on boiling.” (Hoagland, R. 1914)

“It is very probable that in the case of meats which have been cured with saltpeter or of meat food products in which saltpeter has been used in the process of manufacture, the reduction of NO-hemoglobin to NO-hemochromogen takes place to a greater or lesser degree, depending upon conditions of manufacture and storage. The two compounds are so closely allied that their differentiation in one and the same product is not a matter of great importance.” (Hoagland, R. 1914) (6)

Hoagland and other researchers from that period laid the foundation to much of our current understanding of meat curing by drawing a distinction between fresh cured meat colour and cooked cured colour. The first detailed mechanism in the development of cured meat colour that started to emerge was through the action of nitric oxide. The formation of the cured pigment is dependant on two things. Nitrite must be reduced to NO and the secondly, NOmetMB must be converted to NOMb.” (7) I will explain the chemical reaction sequence from nitrite to NO, leading to the formation of NOMb later in another letter.

What excites me no end is not that you choose to enter a field that I devoted my life to. That is not the issue. The fact that I can show you the endless pleasure I derive from this vast field is a privilege. The art of living life well is tied up in our relationship with you guys. This is true for me and Minette! We appreciate having you guys in our lives and our message is to you and your brother, follow your passions. Hold loosely to the things of this world for they are fleeting.

Lots of love from Cape Town,

Dad and Minette.


Further Reading

Difference between Fresh Cured and Cooked Cured Colour of Meat.

Mechanisms of meat curing – the important nitrogen compounds

Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour.


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Notes

(1) Ronald Pegg is currently a professor at the Department of Food Science & Technology, University of Georgia. A great piece appeared about him in FST News (from the University of Georgia Department of Food Science and Technology). “He is a researcher who feels equally at home in the classroom and the laboratory. In addition to inspiring students with the chemistry of chocolate and coffee, he’s become one of the nation’s most sought-after experts on the nutrient content of food and the bioactive compounds that make blueberries, peanuts and other nutritionally dense superfoods so “super.” Pegg joined the faculty of UGA in 2006. He immediately saw the need for a more hands-on, practical approach to teaching food chemistry. His work with students has earned him Food Science and Technology Outstanding Undergraduate and Graduate Professor awards five times. Pegg has received a major teaching honor from his department, the college or the university every year since 2007.” “In addition to his time in the classroom, Pegg has received accolades from producer groups for his research into bioactive chemistry and the health benefits of pecans, peanuts, peaches and other crops.” (http://www.foodscience.caes.uga.edu/)

His research and publishing partner in Nitrite Curing of Meat is Fereidoon Shahidi. He is a university research professor at the Department of Biochemistry, Memorial University of Newfoundland St. John’s, Canada. This monumental food scientist “has received numerous awards, including the 2005 Stephen Chang Award from the Institute of Food Technologists, for his outstanding contributions to science and technology. Between 1996 and 2006, Shahidi was the most published and most frequently cited scientist in the area of food, nutrition, and agricultural science as listed by the ISI.” (wikipedia.org/wiki/Fereidoon_Shahidi)

(2) Our current understanding: Oxymyoglobin (Mb

CodeCogsEqn (1) , bright red, CodeCogsEqn (2) – ferrous state) Oxymyoglobin is the result of myoglobin’s affinity for CodeCogsEqn (1) and it results in a bright red bloom within minutes of fresh meat’s exposure to air. The reaction is rapid and reversible. The continued red bloom depends on a “continuous supply of CodeCogsEqn (1) .” (Pegg, R. B, and Shahidi, F; 2000: 31) This is “because the enzymes involved in oxidative metabolism rapidly use the available CodeCogsEqn (1).” (Pegg, R. B, and Shahidi, F; 2000: 31)

“With time, the small layer of oxymyoglobin present on the surface of the meat propagates downward, but the depth to which CodeCogsEqn (1) diffuses depends on several factors, such as the activity of oxygen-utilizing enzymes (i.e., CodeCogsEqn (1) consumption rate of the meat), temperature, pH, and external CodeCogsEqn (1) pressure. In other words, as air diffuses inward, an CodeCogsEqn (1) and a color gradient are established throughout the meat. Muscles differ in their rates of enzyme activity which, in turn, regulate the amount of CodeCogsEqn (1) available in the outermost layers of tissue. As the pH and temperature of the tissue increase, enzymes become more active and the CodeCogsEqn (1) content is reduced. Consequently, maintaining the temperature of the meat near freezing point minimizes the rate of enzyme activity and the CodeCogsEqn (1) utilization and helps maintain a bright red color for the maximum possible time.” (Pegg, R. B and Shahidi, F; 2000: 31)

(3) Our current understanding: metmyoglobin (metMb, brown, CodeCogsEqn (4)  ferric state)

Methemoglobin and metmyoglobin actually is the brown colour of meat which develops after meat has been standing for some time. Myoglobin exists within the interior of meat and has a purple-red colour. “This is the colour of Myoglobin” (Pegg, R. B and Shahidi, F; 2000: 31) Reductants generated within a cell by enzyme activity prevents the meat from turning brown, until this is no longer available. The heme iron (in the ferrous state – CodeCogsEqn (2)) is oxidized to the ferric state (CodeCogsEqn (4)) . (Pegg, R. B and Shahidi, F; 2000: 31)

It is generated as follows. The superoxide anion (CodeCogsEqn (3).gif) is removed from the hematin. A water molecule is added. This gives a high-spin ferric hematin. “The ferric ion, unlike its ferrous counterpart, has a high nuclear charge and does not engage in strong CodeCogsEqn (5) bonding. Therefore, metmyoglobin is unable to form an oxygen adduct. (Pegg, R. B and Shahidi, F; 2000: 31)

(4) Our current understanding: nitric oxide hemochrome (Cooked Cured Meats – one nitric oxide molecule per heme).

When heated, NO-myoglobin (nitrosyl myoglobin) is transformed to nitrosyl myocromogen, which is denatured NO-myochromogen. This happens upon thermal processing. The globin unfolds (denatures); the iron atom comes loose from the globin; the unfolded globin folds itself around the heme functional part (moiety) which is the iron-porphyrin complex. This brings about the characteristic reddish-pinkish colour of cooked cured meat. (Pegg, R. B and Shahidi, F; 2000: 42)

By way of application, note that “there is a direct relationship between the concentration of NO-myoglobin in the muscle and the intensity of the cured colour” and NOT the nitrite level. “When muscle tissue are cured with equivalent amounts of nitrite, a more intense cured meat colour is produced in,” for example, corned beef as opposed to ham. “The addition of excess nitrite to that required to fix the pigment does not increase the intensity of the cured meat colour.” (Pegg, R. B and Shahidi, F; 2000: 42) This being the case, it is also true that if the concentration of nitrite and therefore nitric oxide formation is to low, that it will impact colour development.

(5) Our current understanding: nitric oxide myoglobin (NOMb, red, CodeCogsEqn (2)).

“When nitrite is added to comminuted meat, the meat turns brown because nitrite acts as a strong heme oxidant. The oxidizing capacity of nitrite increases as the pH of meat decreases, but nitrite itself may also partly be oxidized to nitrate during curing and storage. Myoglobin and CodeCogsEqn (6) are oxidized to metMb by nitrite. The ion itself can be reduced to CodeCogsEqn (13). These products can combine with one another to form an intermediate pigment, nitrosylmetmyogloboin (CodeCogsEqn (8)).” (Pegg, R. B and Shahidi, F; 2000: 40)CodeCogsEqn (9) “Nitrosylmetmyoglobin is unstable. It auto-reduces with time and in the presence of endogenous and exogenous reductants in the postmortem muscle tissue to the corresponding relatively stable Fe(II) form, nitrosylmyoglobin (NOMb).” (Pegg, R. B and Shahidi, F; 2000: 40)

A new suggestion was proposed as a mechanism for the meat curing process by Killday et al. (1988)

meat curing

“They suggested that CodeCogsEqn (8) is more adequately described as an imidazole-centered protein radical. This radical undergoes autoreduction yielding NOMb, and lacking exogenous reductants, reducing groups within the protein can donate electrons to the imidazole radical.” (Pegg, R. B and Shahidi, F; 2000: 40)

An interesting study by Corforth et al. (1998) strengthened the mechanism posed by Killday et al. (1988). “Cornforth and co-workers examined the relative contribution of CO and CodeCogsEqn (11) towards pink ring formation in gas oven cooked beef roast and turkey rolls. Data showed that pinking was not evident with up to 149 ppm of CO or 5 ppm of NO present in the burning gases; however, as little as 0.4 and 2.5ppm of CodeCogsEqn (14) was sufficient to cause pinking of the turkey and beef products, respectively. Cornforth et al. (1998) proposed that pinking previously attributed to CO and NO gas in ovens is instead due to CodeCogsEqn (14) which has much greater reactivity than NO with moisture at the surface of meats. Their argument was predicated on the fact that NO has a low water solubility unlike that of CodeCogsEqn (14) . Therefore on the basis of this consideration, NO would be an unlikely candidate to cause pink ring, since at the low levels typical of gas ovens or smokehouses, NO would be unable to enter the aqueous meat system in sufficient quantity to cause pink ring at depths up to 1 cm from the surface. On the other hand, CodeCogsEqn (14) reacts readily with water to produce nitrous and nitric acid.” (Pegg, R. B and Shahidi, F; 2000: 40, 42)

CodeCogsEqn (12)

“Nitrous acid produced at meat surfaces would be free to diffuse inwards, where endogenous or exogenous meat reductants, including Mb itself may regenerate NO. Nitric oxide binds to MetMb followed by rapid autoreduction to NOMb as suggested by Killday et al. (1988).” (Pegg, R. B and Shahidi, F; 2000: 42)

CodeCogsEqn (13)

CodeCogsEqn (17)

CodeCogsEqn (16)

NOMb is therefore responsible for the characteristic red colour of fresh cured meat before thermal processing. The NOMb pigment can be produced by the direct action of NO on a deoxygenated solution of Mb, but in conventional curing, it arises from the action of nitrite, as stated above. (Pegg, R. B and Shahidi, F; 2000: 42)

(6) Our current understanding: Nitrosylmyochromogen or nitrosylprotoheme.

Upon thermal processing, globin denatures and detaches itself from the iron atom and surrounds the hem moiety. Nitrosylmyochromogen or nitrosylprotoheme is the pigment formed upon cooking , and it confers the characteristic pink colour to cooked cured meats.” (Pegg, R. B and Shahidi, F; 2000: 44)

“Although the Cooked Cured Meat Pigment (CCMP) is a heat-stable NO hemochrome as evident by the fact that it doesnt undergo further colour change upon additional thermal processing, it is susceptible to photodissociation. Furthermolre in the presence of oxygen, CCMP’s stability is limited by the rate of loss of NO.

CodeCogsEqn (18)

This effect is important if cured meats are displayed under strong fluorescent lighting while they are also exposed to air. Under these conditions, the surface colour of cured meat will fade in a few hours, whereas under identical conditions, fresh meat will hold its colour for a few days.” “A brownish-gray colour develops on the exposed meat surface during colour fading; this pigment, sometimes called hemichrome, has its heme group in the ferric state. The most effective way of preventing light fading is to exclude CodeCogsEqn (1) contact with the cured meat surfaces. It is routinely accomplished by vacuum packaging the meat in CodeCogsEqn (1) impermiable films. If CodeCogsEqn (1) is absent from the package, NO cleaved from the heme moieties by light cannot be oxidized and can recombine with the heme.” (Pegg, R. B and Shahidi, F; 2000: 44)

(7) An interesting side note. Hoagland wondered if it is possible to produce the cooked cured colour of meat in another way than curing with nitrite and heat treatment. Pegg and Shahidi have dedicated much work along similar lines – to identify a curing system that will replace nitrite curing. In meat curing, this has always been the holy grail which on the one hand will in all likelihood remain an unattainable concept and on the other hand, as our understanding of nitrite grows, will be deemed unnecessary.


References:

The Bismarck Tribune (Bismarck, North Dakota); 10 July 1912; page 2.

Cole, Morton Sylvan, “Relation of sulfhydryl groups to the fading of cured meat ” (1961). Retrospective Theses and Dissertations. Paper 2402

Haldane, J. S.. 1901. The Red Colour of Salted Meat. Journal of Hygiene 1: 115 – 122

Hoagland, R. 1914. Cloring matter of raw and cooked salted meats. Laboratory Inspector, Biochemie Division, Bureau of Animal Industry. Journal of Agricultural Research, Vol. Ill, No. 3 Dept. of Agriculture, Washington, D. C. Dec. 15, 1914.

Lemberg, R. and Legge, J. W.. 1949. Hematin Compounds and Bile Pigments. Interscience Publishers, Inc.

Soltanizadeh, N., Kadivar, M.. 2012. A new, simple method for the production of meat-curing pigment under optimised conditions using response surface methodology. Meat Science 92 (2012) 538–547 Elsevier Ltd.

http://cbs.umn.edu/academics/departments/bmbb/about/history/timeline

http://www.foodscience.caes.uga.edu/documents/Newsletter2016June16colorforweb.pdf

https://en.wikipedia.org/wiki/Fereidoon_Shahidi

http://www.medicinenet.com

Images:

Image 1: Ralph Hoagland. Oakland Tribune, 5 July 1927

Chapter 11.01: The Fathers of Meat Curing

 

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


The Fathers of Meat Curing

June 1959

Dear Tristan,

Amsterdam is one of the greatest cities on earth and for someone with your adventurous spirit, it is perfect. I remember that you had a small cannabis garden back home in Cape Town. This makes your move to Amsterdam all the more appropriate! You already know the culture.

Hashish, another name for cannabis, has been used since antiquity as an anesthetic. It was described in the “Arabian Nights” by the name bhang. Bhang was smoked like a cigarette or taken orally in tablet form. Some mix it with sugar and eat it like candy and still, I heard that some create a green liquid from it to serve as a drink. I love your passion for the natural world and your desire to make money! Follow your dream! 🙂

T-man, since you and your sister have been entreating me to complete my work on bacon, I decided to begin with a review of everybody that I found over the years who had an impact on unraveling the mystery of meat curing. Many of the men and women did this without even realising the value of their discoveries to the inquisitive bacon factory or production manager.

I will complete this work, but you and Lauren have to promise me that before you eventually publish my work, you will add the most recent discoveries to my letters in this section of the work. This way, it will remain current and useful to the curing professional or the layperson who wants to know bacon curing or those who are simply interested in a great story will know they have the latest version with all the facts available to us!

Nitric Oxide

A study of curing is a study in the interaction between nitrogen, oxygen with a meat protein, myoglobin, with an auxiliary role for blood proteins, haemoglobin. It is about oxygenation, protonation, and reduction. It has recently been discovered that there exists a close correlation between certain reactions in human physiology and meat curing – the exact same processes are involved which means that in the basic meat curing reaction, it so happens that we merely mimic a biological process in our bodies. I decided to begin my letters from the Union of South Africa by giving you an overview of some of the men and women who contributed to our understanding of the curing process and their important contributions.

In the letters following, I will circle back and go into some detail into the important discoveries which I touch on in this overview.  There have been many important advances in our understanding of the curing reaction over the years since 1893 and they all begin with a far greater understanding of proteins on the one hand and nitrogen compounds and its role in curing on the other hand.  We discovered, for example, that meat curing begins with a bacterial reduction of saltpeter (nitrate) to nitrite and then a chemical reduction of nitrite to Nitric Oxide (NO).  It is the interaction of this molecule with protein which gives the meat its reddish/ pinkish colour and the important protein that it interacts with, in the muscle, turns out to be myoglobin.

Here I must caution you that early work was done by giving the interaction of nitric oxide with a protein found in blood, haemoblobin (Hemoglobin – American English; haemoglobin (British English).  This should not alarm you.  Let me explain what I mean.

Haemoglobin and Myoglobin

One of the proteins in the blood cell is haemoglobin. It is a red protein that is responsible for transporting oxygen in our blood. Early researchers in meat curing did their trails on it. In recent years we discovered that the curing reaction is not so much the effect of curing agents on haemoglobin, as it is in reality, the reaction with a meat protein found in all muscles, myoglobin. The oxygen is passed from the haemoglobin in the blood to the myoglobin, located in the muscle. We can say it is the cell oxygen reservoir. When you work out and the blood oxygen delivery is not enough, it temporarily provides oxygen.

The reason for using haemoglobin was “mostly a matter of convenience” and “a matter of necessity since myoglobin was not isolated and purified until 1932 (Theorell, 1932).” “In spite of the differences between haemoglobin and myoglobin, Urbain and Jensen (1940) considered the properties of haemoglobin and its derivatives sufficiently like those of myoglobin to allow the use of haemoglobin in studies of meat pigments.” (Cole, Morton Sylvan, 1961: 2)

These are then some of the fathers of meat curing and processes that were elucidated by them. In the case of Da Vinci, he is one of many people who’s work provides a link back to our ancient past and the art of meat curing that is thousands of years old. Our art is built, in huge part, on the foundations the following people laid.

7000 BCE to 3000 BCE

Good evidence suggests that meat curing has been practiced with sodium or potassium nitrate at various locations around the world where it naturally appears as a salt. Four locations stand out. The Atacama Desert in Chile and Peru, the Tarim Basin in Western China, the Dead Sea, and Egypt. It is in the Tarim Basin, where I believe, it was first developed into the art that we recognise today with a level of sophistication in the application of saltpeter by the early Christian Era that has not been fully appreciated until recently (1987).

LEONARDO DA VINCI

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Leonardo da Vince (1452–1519) described a method of preserving the cadavers for his own dissection and study. (Brenner, E.; 2014) The mixture he used consisted of turpentine, camphor (scent masking), oil of lavender (scent masking), vermilion (colouring agent), wine, rosin (a resin used as an adhesive), sodium nitrate, and potassium nitrate. In his mix, for preservation, he relied on sodium and potassium nitrate and turpentine. It is clear from these and other examples that the preserving power of nitrates was well known, well before modern-day scientific rigour would come to the same conclusions. The knowledge of the particular taste imparted, the colour formation and the preserving power of curing through nitrate, nitrite and nitric oxide has been harnessed for thousands of years.

GLAUBER, PRIESTLY, CAVENDISH, DAVEY

It is generally believed that nitric oxide, the chemical compound responsible for meat curing, was discovered by Joseph Priestly in 1772. This is not completely true. Before the time of Priestly, the production of nitric oxide was known through the reaction of nitric acid (CodeCogsEqn(7)) with any one of a number of commonly available metals. Nitric acid was, for example, known in the 13th century Europe and was known as aqua fortis. A known way of making it was was to react sulphuric acid and potassium nitrate as was developed by Johann Glauber (1604 – 1670). It was observed that a gas was formed when nitric acid was poured over copper, iron, or silver by a number of natural philosophers including Johannes van Helmont (1579 – 1644), Robert Boyle (1627 – 1691) and Georg Stahl (1660 – 1734). The last two noticed that this gas forms brown fumes when it comes in contact with the atmosphere.

Priestly’s contribution was immense in terms of identifying NO as a distinct chemical entity, separate from other gasses or “airs.” Priestly made important discoveries related to NO and was able to characterise it, but it was the eccentric and brilliant Henry Cavendish (1778 – 1810) who showed that NO is a composition of nitrogen and oxygen. Humphrey Davey (1778 – 1829) showed the diatomic nature of the compound (Butler, A. R., Nicholson, R.; 2003).

CARL WILHELM SCHEELE

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In 1777, the prolific Swedish chemist Scheele, working in the laboratory of his pharmacy in the market town of Köping, made the first pure nitrite. (Scheele CW. 1777) He heated potassium nitrate at red heat for half an hour and obtained what he recognised as a new “salt.” He realised that there was more than one “acid of niter.” He distinguished phlogisticated acid of niter or nitrous acid (HNO2), as it became known in the 1800s, from nitric acid (HNO3) as being a weaker volatile acid produced by the reduction of nitric acid. He also showed that niter, when strongly heated, lost oxygen, and left a salt that readily decomposed into a volatile acid when treated with acid. (http://nitrogen.atomistry.com/)

The two compounds (potassium nitrate and nitrite) were characterised by Péligot and the reaction established as 2KNO3→2KNO2+O2. (Péligot E. 1841: 2: 58–68) (Butler, A. R., and Feelisch, M.) (Butler, A. R., and Feelisch, M.)

ANTOINE-LAURENT DE LAVOISIER

Antoine de Lavoisier (1743 – 1794), the father of modern chemistry did landmark work on nitric acid. In 1790 he coined the terms nitrate and nitrite. In his work on nitric acid, he noted that different oxidation states of nitrogen have been known for some time. The term niter was allocated to these compounds by Macquer and Beaumé, but Lavoisier changed this to nitrites and nitrates “as they are formed by nitric or by nitrous acid.” (Lavoisier, A; 1965: 217)

CARL REMIGIUS FRESENIUS

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A private laboratory was founded in 1848 in Germany by C. R. Fresenius (his doctoral advisor was none other than Justus von Liebig). One of the first recorded tests of nitrite as a meat preservative took place at his laboratory. (Morton, I. D. and Lenges. J.,1992: 142)

JUSTINUS KERNER

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Kerner in Germany makes the link between Saltpetre and food safety particularly in relation to the prevention of botulism. After studying many outbreaks of botulism, he identifies the omission of saltpeter from the curing brine as the common denominator in the various outbreaks. (1817, 1820, 1822) (Peter, F. M. (Editor), 1981.)

HÜNEFELD

Hünefeld in 1840 observed a crystalline substance in the blood of an earthworm thus discovering haemoglobin. “Reichert, von Kolliker, Leydig, Budge, Kunde, and many others noted that blood from various species yielded a similar crystalline substance. As early as 1852 Funke described the method of laking blood with water and then inducing crystal formation with alcohol and ether. Laking is defined as “the physical or chemical treatment of blood to abolish the structure of the red cells and thus form a homogeneous solution. Laking is an important preliminary step in the analysis of haemoglobin or enzymes present in red cells.” Although he prepared only small quantities of haemoglobin, the principle of this method has been widely used” for many years. (Ferry, R. M.; 1923)

HUMPHREY DAVY

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Humphrey Davy (1778 – 1829) in 1812 (cited by Hermann, 1865) and Hoppe-Seyler (1864) was the first to note the action of nitric oxide upon haemoglobin. (Hoagland, R.; 1914: 213)

HERMANN

Hermann studied the properties of the compound formed in the reaction between haemoglobin and nitric oxide. He discovered the compound Nitric Oxide-Hemoglobin (NO-Hemoglobin) in 1865 and it was supposed that it existed only in a laboratory. Until the work of Haldane, the compound has not attracted much attention. (Haldane, J. 1901)

Hermann showed the spectrum of oxyhemoglobin and NO-hemoglobin. “The blood saturated with nitric oxide was found to be darker in colour than either arterial blood or that saturated with carbon monoxide.” (Hoagland, R.; 1914: 213)

T. LAUDER BRUNTON

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In 1867, Brunton identifies nitrite as a treatment for angina, the first nitrovasodilator. His story is interesting and I quote a section edited by Hurst, J. W. from a 1989 article that appeared in Clinical Cardiology.

“Brunton learned of amyl nitrite from faculty members at Edinburgh who were interested in this substance that had been synthesised in 1844 by the French chemist Antoine Balard.” (Hurst, J. W.; 1989) Antoine-Jerome Balard achieved this when he passed nitrogen fumes through amyl-alcohol. An interesting liquid was formed. It had a pungent smell and when he inhaled it, it made him blush. He told a friend that he is a shameless character and nothing makes him blush. He speculated that the compound dilated the blood vessels and caused a drop in blood pressure. Bruton thought that anything that dilated the blood vessels of the skin may have the same effect on the heart. (Dormandy, 2006)

“London physician Benjamin Ward Richardson discussed possible medical uses of amyl nitrite at meetings of the British Association for the Advancement of Science between 1863 and 1865. Arthur Gamgee, a recent Edinburgh graduate, also studied the physiological effects of amyl nitrite and encouraged Brunton to continue these investigations when he discovered that inhalation of the substance reduced arterial tension as measured by the sphygmograph.” (Hurst, J. W.; 1989)

“While a house physician at the Edinburgh Royal Infirmary, Brunton became impressed with the lack of effective treatment for angina pectoris. Although the popularity of therapeutic bleeding had declined by the late 1860s, it was still advocated for the treatment of angina by some authors. When Brunton bled patients with angina some of them seemed to improve. He explained, “As I believe the relief produced by the bleeding to be due to the diminution it occasioned in the arterial tension, it occurred to me that a substance which possesses the power of lessening it in such an eminent degree as nitrite of amyl would probably produce the same effect, and might be repeated as often as necessary without detriment to the patient’s health.” Brunton began to study the effects of amyl nitrite on patients in the Edinburgh Royal Infirmary. When it was administered to patients with chest pain thought to represent angina, the discomfort usually disappeared in less than a minute. This was accompanied by facial flushing – an outward sign of the effect of amyl nitrite on the vascular system. Brunton published his observations on the value of amyl nitrite in angina in Lancet in 1867. Amyl nitrite was rapidly accepted by practitioners as an effective agent for angina pectoris.” (Hurst, J. W.; 1989)

The reason for this inclusion is the fact that amyl nitrite, like alkyl nitrites, as discovered by Brunton, is a very effective vasodilator. How it achieves this is that alkyl nitrite is a source of nitric oxide, which signals for relaxation of the involuntary muscles. Some of the physical effects are a decrease in blood pressure, headache, flushing of the face, increased heart rate, dizziness, and relaxation of involuntary muscles.

It has been discovered that nitrites and nitric oxide perform this function in the human body as a normal course of physiology. The reduction step of nitrite to nitric oxide which is the final step in meat curing turns out to be an essential mechanism in the human body that makes life possible. The full effect of Brunton’s discovery and the link with NO formation would not be realised until 1987 (Salt – 7000 years of meat curing).

There is another interesting reason. A friend of mine, Gero Lütge, a 3rd generation German Master Butcher grew up in the German town of Braunschweig in Lower Saxony, Germany.

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Apprenticeship book of Otto Lütge, qualified butcher in 1927.

If anyone can tell you anything about meat, it is Gero and as someone who inherited his trade from his father and grandfather, he is a rich source of historical anecdotes, illustrations, and information! He tells the story of his grandfather, Otto Lütge, who used to buy nitrite for meat curing, from the pharmacy. That would have been somewhere between the years 1950 and 1970 before it actually was regulated by law.

He confirmed that it was indeed nitrite and not nitrate that his grandfather added. The colour was more intense and stable, but health issues were a big concern, in particular, cancer from which he himself passed away.

Butchers could have bought nitrate also from the pharmacy. Following Bruton’s application of amyl nitrite for chest pains, William Murrell experimented with glyceryl nitrate to treat angina pectoris and to reduce blood pressure. After Murrell published on it in 1879, it became widely available as a remedy. It was officially known as glyceryl trinitrate, but due to a longer curing time, butchers would have preferred nitrite and in all likelihood, if they bought it through pharmacies, it would have been amyl nitrite. Fascinatingly, this indicates that there is a possibility that amyl nitrite was used in meat curing.

ARTHUR GAMGEE

On 7 May 1868, Dr. Arthur Gamgee, who studied the physiological effects of amyl nitrite along with Brunton at the University of Edinburgh, brother of the famous veterinarian, Professor John Gamgee (who contributed to the attempt to find ways to preserve whole carcasses during a voyage between Australia and Britain), published a groundbreaking article entitled, “On the action of nitrites on the blood.” He observed the colour change brought about by nitrite. He wrote, “The addition of … nitrites to blood … causes the red colour to return…” Over the next 30 years, it would be discovered that it is indeed nitrites responsible for curing and not the nitrates added as saltpeter.

MEUSEL, GAYON, AND DUPETIT

The important reduction process of nitrate to nitrite was identified by E. Meusel (1875) who was the first to associate microorganisms with nitrogen losses. He noted that antiseptic-sensitive agents identified as mixed populations of bacteria in soil and natural waters reduced nitrates to nitrites and even further. (Meusel, E. 1875) Gayon and Dupetit coined the term denitrification in 1882. (Gayon, U., and G. Dupetit; 1883) It was this knowledge that was the basis of Polenske’s speculation about the source of nitrite in curing brine and cured meat. (See Saltpeter: A Concise History and the Discovery of Dr Ed Polenske)

POLENSKE

Dr. Ed Polenske (1849-1911), working for the Imperial Health Office in Germany, made the first discovery that would lead to a full understanding of the curing action. He prepared a brine to cure meat and used only salt and saltpeter (nitrates). When he tested it a week later, it tested positive for nitrites.

The question is where did the nitrites come from if he did not add it to the brine to begin with. He correctly speculated that this was due to nitrate being converted by microbial action into nitrite. He published in 1891. For a full discussion on this landmark article, see Saltpeter: A Concise History and the Discovery of Dr Ed Polenske

NOTHWANG

Following Dr. Polenski’s observation, the German scientist, Nothwang confirmed the presence of nitrite in curing brines in 1892 but attributed the reduction from nitrate to nitrite to the meat tissue itself. The link between nitrite and cured meat colour was finally established in 1899 by another German scientist, K. B. Lehmann in a simple but important experiment.

LEHMANN

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Karl Bernhard Lehmann (1858 – 1940) was a German hygienist and bacteriologist born in Zurich.

In an experiment, he boiled fresh meat with nitrite and a little bit of acid. A red colour resulted, similar to the red of cured meat. He repeated the experiment with nitrates and no such reddening occurred, thus establishing the link between nitrite and the formation of a stable red meat colour in meat.

K. B. Lehmann made another important observation that must be noted when he found the colour to be soluble in alcohol and ether and to give a spectrum showing an absorption band just at the right of the D line, and a second band, often poorly defined, at the left of the E line. On standing, the colour of the solution changed to brown and gave the spectrum of alkaline hematin, the colouring group.

KIßKALT

In the same year, another German hygienists, one of Lehmann’s assistants at the Institute of Hygiene in Würzburg, Karl Kißkalt (1875 – 1962), confirmed Lehmann’s observations and showed that the same red colour resulted if the meat was left in saltpeter (potassium nitrate) for several days before it was cooked.

HALDANE

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The brilliant British physiologist and philosopher, John Scott Haldane weighed in on the topic. He was born in 1860 in Edinburgh, Scotland. He was part of a lineage of important and influential scientists.

J. S. Haldane contributed immensely to the application of science across many fields of life. This formidable scientist was for example responsible for developing decompression tables for deep-sea diving used to this day.

“Haldane was an observer and an experimentalist, who always pointed out that careful observation and experiments had to be the basis of any theoretical analysis. “Why think when you can experiment” and “Exhaust experiments and then think.” (Lang, M. A., and Brubakk, A. O. 2009. The Haldane Effect)

S. J. Haldane applied the same rigour to cured meat and became the first person to demonstrate that the addition of nitrite to haemoglobin produce a nitric oxide (NO)-heme bond, called iron-nitrosyl-hemoglobin (HbFeIINO).

Haldane showed that nitrite is further reduced to nitric oxide (NO) in the presence of muscle myoglobin and forms iron-nitrosyl-myoglobin. It is nitrosylated myoglobin that gives cured meat, including bacon and hot dogs, their distinctive red colour and protects the meat from oxidation and spoiling.

This is how he discovered it. Remember the observation made by K. B. Lehmann that the colour of fresh meat cooked in water with nitrites and free acid to give a spectrum showing an absorption band just at the right of the D line, and a second band, often poorly defined, at the left of the E line.

Haldane found the same colour to be present in cured meat. That it is soluble in water and giving a spectrum characteristic of NO-hemoglobin. The formation of the red colour in uncooked salted meats is explained by the action of nitrites in the presence of a reducing agent and in the absence of oxygen upon haemoglobin, the normal colouring matter of fresh meats. He showed that the redox reaction occurs in meat during curing (1901).

Haldane finally showed the formation of nitrosylhemochromogen from nitrosylhemoglobin (nitrite added to haemoglobin) when thermal processing has been applied and identified this as the pigment responsible for the cooked cured meat colour. He attributed this formation to NO-hemoglobin denaturing into two parts namely hemin (the colouring group) and the denatured protein (1901).

HOAGLAND

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Ralph Hoagland was the Senior Biochemist, Biochemie Division, Bureau of Animal Industry, United States Department of Agriculture in Chicago. Prior to this appointment, Hoagland was the department head of the Minnesota College of Agriculture (part of the University of Minnesota), appointed in 1909. Presently, the College of Agriculture is the College of Biological Sciences. (http://cbs.umn.edu/ and The Bismarck Tribune; 1912)

In 1908 he published results obtained upon studying the action of saltpeter upon the color of meat and “found that the value of this agent in the curing of meats depends upon its reduction to nitrites and nitric oxide, with the consequent production of NO-hemoglobin, to which compound the red color of salted meats is due.” He found that “saltpeter, as such, [had] no value as a flesh-color preservative.” (Hoagland, R. 1914.)

The results of his 1914 publication are summarised by himself as follows:

a. The colour of uncooked salted meats cured with potassium nitrate, or saltpeter, is generally due, in large part at least, to the presence of NO-hemoglobin, although the colour of certain kinds of such meats may be due in part or in whole to NO-hemochromogen. (Hoagland, R. 1914.)

b. The NO-hemoglobin is produced by the action of the nitric oxide resulting from the reduction of the saltpeter used in salting upon the haemoglobin of the meat. (Hoagland, R. 1914.)

c. The colour of cooked salted meats cured with saltpeter is due to the presence of NO-hemochromogen resulting from the reduction of the colour of the raw salted meat on cooking. (Hoagland, R. 1914.)

BARCROFT AND MULLER

They did not discover the link between nitrite and methaemoglobin, but they were the first to venture an opinion in 1911 on the quantitative relationship that exists between nitrite added and the formation of methaemoglobin. (reported by Greenberg, L. A. et al.; 1943) This is a form of haemoglobin where the iron in the heme group is in the ferrous (CodeCogsEqn (1)) state and not in the ferric (CodeCogsEqn (2)) state. In this state, it can not bind oxygen and in the body, an enzymic action is required to convert it back to haemoglobin.

The reason why haemoglobin turns brown is that nitrite is a very strong heme oxidant. It is the same reason why meat (in particular comminuted meat) that has been injected or tumbled with nitrite also turns brown. This capacity of nitrite increases as the pH decreases. Nitrite itself may be partially oxidised to nitrate during the process of curing and during storage. (Pegg and Shahodi, 2000)

LADISLAV NACHMÜLLNER

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In 1915, at age 19, Ladislav Nachmüllner invents Praganda, the first legal commercial curing brine containing sodium nitrite in the city of Prague. He says that he discovered the power of sodium nitrite through “modern-day professional and scientific investigation.” He probably actively sought an application of the work of Haldane. He quotes the exact discovery that Haldane was credited for in 1901 that nitrite interacts with the meat’s “haemoglobin, which is changing to red nitro-oxy-haemoglobin.” (The Naming of Prague Salt)

MITCHELL AND COLLABORATORS

In February 1916, H. H. Mitchell, H. A. Shonle and H. H. Grindley from the Department of Animal Husbandry at the University of Illinois, Urbana, published “The Origin of the Nitrates in the Urine,” showing that mammals produce nitrate.

LEWIS AND MORAN

In 1928, these researchers suggested that nitrite had antimicrobial efficacy. This was later confirmed by others. (example Evans and Tanner, 1934; Tarr, 1941, 1942, 1944). This becomes one of the great examples of the discovery and continued re-discovery of the same fact by successive civilisations. Beginning with Lewis and Morgan, the antimicrobial efficacy of nitrite was now being subjected to a modern scientific scrutiny despite thousands of years of evidence to the facts. (Peter, F. M. (Editor), 1981)

BROOKS

The reaction of nitrite through the formation of nitrous acid and “its reaction with deoxyhemoglobin to form nitric oxide (NO) and methemoglobin was more fully described by Brooks in 1937. (Gladwin, M. T., et al.; 2008)

DOYLE

The mechanism and unusual behaviour of the reaction of nitrite with deoxyhemoglobin and nitric oxide formation are further described by Doyle and colleagues in 1981.” (Gladwin, M. T., et al.; 2008)

STEINKE AND FOSTER

In 1951 they became the first to demonstrate conclusively the antimicrobial efficacy of nitrite in meat products when added at the levels in use today by commercial curing operations. (Peter, F. M. (Editor), 1981)

H. C. HORNSEY

In 1956 he demonstrated that the characteristic red pigment of cooked cured meat could be extracted completely by an 80% acetone-water mixture. This made the collection of data on the electronic absorbance and reflectance of the cooked cured meat pigment possible and provided an invaluable tool for future researchers. (Hornsey, 1956)

JOHN KENDREW AND MAX PERUTZ

“In 1958 and 1960 molecular biologist John Kendrew published “A Three-Dimensional Model of the Myoglobin Molecule Obtained by X-ray Analysis” (with G. Bodo, H. M. Dintzis, R. G. Parrish, H. Wyckoff,) Nature 181 (1958) 662-666, and “Structure of Myoglobin: A Three-Dimensional Fourier synthesis at 2 Å Resolution” (with R. E. Dickerson, B. E. Strandberg, R. G. Hart, D. R. Davies, D. C. Phillips, V. C. Shore). Nature 185 (1960) 422-27). These papers reported the first solution of the three-dimensional molecular structure of a protein, for which Kendrew received the 1962 Nobel Prize in chemistry, together with his friend and colleague Max Perutz, who solved the structure of the related and more complex protein, haemoglobin, two years after Kendrew’s achievement.” (www.historyofinformation.com) This becomes a crucial tool to progress our understanding of the interaction of nitrite and nitric oxide with the meat protein.

SALVADOR MONCADA AND LOUIS IGNARRO

A phenomenal discovery was made when nitric oxide was identified as a key signaling molecule in human physiology, showing that meat curing is a “natural process”. “Lining almost all blood vessels on the inside is a layer of cells known as the endothelium. A very important function of the endothelium was first reported in 1890 by Furchgott and Zawadzki. The presence of acetylcholine (a small biologically active molecule) in the bloodstream affects vasodilation and it was generally assumed that acetylcholine acted directly upon vascular muscle. However, this was found not to be the case. Furchgott and Zawadzki showed convincingly that that acetylcholine acted, not upon the muscle of the artery, but upon the endothelium and the endothelium produces a “second messenger” which then acts upon the muscles to effect relaxation. This second messenger was christened “the endothelium-derived relaxing factor” (EDRF).” (Cullen, C, Lo, V.; 2005)

During the 1980’s, an intense effort was effected to identify the EDRF. It was initially assumed that it would turn out to be a complex molecule like a hormone. This speculation enhanced the surprise when the chemical nature of the molecule was finally determined. It turned out to be a small diatomic molecule called Nitric Oxide (NO). “That it had a physiological role, in a process as important as vasodilation, came as a complete surprise.” (Cullen, C, Lo, V.; 2005)

“The discovery was made simultaneously by a group at the Wellcome Research Laboratories in Beckenham led by Professor Salvador Moncada and by a group in the USA led by Professor Louis Ignarro. The 1998 Nobel Prize in Physiology and Medicine was awarded for this discovery. Once nitric oxide had been detected in one physiological process it was found to have roles in many others, from inflammation to crying.” (Cullen, C, Lo, V.; 2005)

The debate on the safety of nitrites and nitrates in meat curing is not settled by these developments. What it does is to bring to bear much greater interest upon nitrite and nitric oxide and their role in human physiology, including the health risks associated with their intake. It is nevertheless an astounding fact that meat curing has, through the ages, kept so close to natural physiological processes.

These formidable scientists laid the scientific foundation for the full understanding of the mechanism behind curing. All questions have still not been answered, but we continue to build on the work of these men. Together, their work shapes our understanding of the action of nitric oxide on blood and muscle protein. Meat curing is, in the end, a natural process that has been practiced for thousands of years.

There is a fundamental lesson here. We do not live in isolation. We stand on the shoulders of many diligent students of life and nature before us and we do well to go back to the origin of every important discovery. The most basic understanding of anything is fundamental to every subsequent discovery. This is true about bacon as well as to the art of living.

Lots of love from Cape Town,

Dad and Minette.


Further Reading

The Fathers of Meat Curing

Concerning the direct addition of nitrite to curing brine

The Naming of Prague Salt


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Notes

References

Extracts from:

Concerning the direct addition of nitrite to curing brine

The Naming of Prague Salt

Additional information references:

The Bismarck Tribune (Bismarck, North Dakota); 10 July 1912; page 2.

Brenner, E.. 2014. Human body preservation – old and new techniques Erich Brenner. J. Anat.(2014) 224, pp316–344 doi: 10.1111/joa.12160

Butler, A. R., Nicholson, R.. 2003. Life, Death and Nitric Oxide. Royal Society of Chemistry.

Butler, A. R. and Feelisch, M. New Drugs and Technologies. Therapeutic Uses of Inorganic Nitrite and Nitrate From the Past to the Future. From: http://circ.ahajournals.org/content/117/16/2151.full

Cole, Morton Sylvan, “Relation of sulfhydryl groups to the fading of cured meat ” (1961). Retrospective Theses and Dissertations. Paper 2402

Cullen, C, Lo, V.. 2005. Medieval Chinese Medicine: The Dunhuang Medical Manuscripts. Routledge Curzon.

Dormandy, T.. 2006. The Worst of Evils: The Fight Against Pain. Yale University Press.

Ferry, R. M.. 1923. STUDIES IN THE CHEMISTRY OF HEMOGLOBIN.
Department of Physical Chemistry, in the Laboratory of Physiology; Harvard Medical School, Boston
Gladwin, M. T., Grubina, R., Doyle, M. P.. 2008. The New Chemical Biology of Nitrite Reactions with Hemoglobin: R-State Catalysis, Oxidative Denitrosylation, and Nitrite Reductase/Anhydrase. Acc. Chem. Res., 2009, 42 (1), pp 157–167, DOI: 10.1021/ar800089j, Publication Date (Web): September 11, 2008, American Chemical Society

Greenberg, L. A. Lester, D., Haggard, H. W., 1943. THE REACTION OF HEMOGLOBIN WITH NITRITE, From the Laboratory of Applied Physiology, Yale University, New Haven, Received for publication, September 10, 1943.

Gayon, U., and G. Dupetit. 1883. La fermentation des nitrates. Mem. Sot. Sci. Phys. Nat. Bordeaux Ser. 2. 5:35-36.

Haldane, J. 1901. The Red Colour of Salted Meat.

Hoagland, R. 1914. Cloring matter of raw and cooked salted meats. Laboratory Inspector, Biochemie Division, Bureau of Animal Industry. Journal of Agricultural Research, Vol. Ill, No. 3 Dept. of Agriculture, Washington, D. C. Dec. 15, 1914.

Hornsey, H. C. “The Colour of Cooked Cured Pork. I. Estimation of the Nitric oxide-Haem Pigments”. J. Sci. Food Agric. 1956, 7, 534-540.

Hurst, J. W., 1989. M. D., T. Lauder Brunton, 1844- 19 16, w. B. FYE, M.D Cardiology Department, Marshfield Clinic, Marshfield, Wisconsin, USA. Clin. Cardiol. 12, 675-676 (1989)

Lavoisier, A. 1965. Elements of Chemistry. Dover Publications, Inc. A republication of a 1790 publication

Mitchell, H. H.., Shonle, H. A., Grindley, H. S.. 1916. THE ORIGIN OF THE NITRATES IN THE URINE, From the Department of Animal Husbandry, University of Illinois, Urbana

Morton, I. D. and Lenges. J. 1992. Education and Training in Food Science: A Changing Scene. Ellis Hornwood Limited.

Meusel, E. 1875. De la putrefaction produite par les batteries, en presence des nitrates alcalins. C. R. Hebd. Seances Acad. Sci. 81:533-534.

Peter, F. M. (Editor), 1981. The Health Effects of Nitrate, Nitrite, and N- Nitroso Compounds. Part 1. National Acadamy Press

Pegg, R. B. and Shahidi, F.. 2000. Nitrite curing of meat. Food & Nutrition Press, Inc.

Péligot E. 1841. Sur l’acide hypoazotique et sur l’acide azoteux. Ann Chim Phys.; 2: 58–68.

Scheele CW. 1777. Chemische Abhandlung von der Luft und dem Feuer. Upsala, Sweden: M. Swederus.

http://cbs.umn.edu/academics/departments/bmbb/about/history/timeline

http://www.historyofinformation.com/expanded.php?id=3015

Photo Credits:

L Da Vinci: https://www.codeavengers.com/c/gabrielj/leonardodavinci.html

Carl Scheele: http://www.explicatorium.com/biografias/carl-sheele.html

Justinus Kerner: https://en.wikipedia.org/wiki/Justinus_Kerner

C. R. Fresenius: https://de.wikipedia.org/wiki/Carl_Remigius_Fresenius

Humphrey Davy: https://global.britannica.com/biography/Sir-Humphry-Davy-Baronet

Lehmann: http://www.kumc.edu/

J S Haldane: https://en.wikipedia.org

T. LAUDER BRUNTON: Hurst, J. W., 1989. M. D., T. Lauder Brunton, 1844- 19 16, w. B. FYE, M.D Cardiology Department, Marshfield Clinic, Marshfield, Wisconsin, USA. Clin. Cardiol. 12, 675-676 (1989)

Hoagland. Popular Science. 1912.

Photo References

Chapter 11.00: The Union Letters

Bacon & the Art of Living 1

Introduction to Bacon & the Art of Living

The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.

The cast I use to mould the story into is letters I wrote home during my travels.


The Union Letters

Sea Point, Cape Town,
1959

The quest to understand Bacon and the Art of Living has by 1959 consumed 66 years of my time on earth.  I have lived through three major wars.  The second Anglo Boer War which was fought between 11 October 1899 and 31 May 1902 and the First and the Second World War which occurred respectively between 28 July 1914 – 11 November 1918 and 1 September 1939 – 2 September 1945.

When the sun sets over the Atlantic, Minette and I sit in our Seapoint apartment, watching it cast its deep orange cloak over our world.  We play chess or cards on the balcony which has been turned into a sunroom when we enclosed it with glass a few years ago.  We slowly sip on Gyn and remiss about the old days.  In the morning we walk along the sea point promenade to stay active.  We have not been up on Table Mountain for some years now.  At night we stay home and enjoy each other’s company.

Tristan and Lauren

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Tristan and Lauren have each gone their own way.  Tristan followed his own passion when he joined a travel firm based in Australia.  Lauren studies BSc Chemistry, majoring in Biochemistry.  Tristan completed BA Accounting which he did part-time.  They both outgrew the difficulties associated with one childhood and have their own amazing families to take care of.

Woody’s Bacon

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Oscar and I grew Woodys into the largest supplier to retail in South Africa of own branded products for outlets like Pick ‘n Pay and Checkers producing 15 tonnes of the best bacon on earth every day.  We both decided its time to bid our baby farewell when Oom Koos and Duncan took the company over during the depression years and we both decided to follow other meat-related ambitions.

Letters from the Union – Therapy for an Old Man

The kids kept asking me for years to write down my memories from 1893 to 1959 and compile this, together with the letters I wrote them, Dawie Hyman, David de Villiers Graaff, and Oscar when I was abroad, learning the art of producing the best bacon on earth.  After many years of dragging my feet, I finally decided to take them up on the request.  The idea came to me when Tristan and Lauren were both living in Europe and North America respectively.  I find it difficult to make small talk on the telephone.  In order to give structure to my letters to them, I decided to pick up where I left off in 1893 when I wrote them my last letter about bacon from New Zealand.  They were both pleased with the suggestion since it gives us regular contact and I fulfill their request for completing my work on bacon.

Imperial Cold Storage & Supply Co.

Prospectus ICS
The prospectus of the company replacing Combrinck & Co. in 1899.

David de Villiers Graaff ultimately changed the name of Combrinck & Co. to the Imperial Cold Storage and Supply Co.  He made his fortune at least three times.  The one time was when the city wanted to expand the railway station at the bottom of Adderly Street and needed to relocated Combrink & Co..  The location where they wanted to move the butchery business to as well as the money in compensation were both in dispute.  After a process of arbitration, an astronomical amount of  £55 000 was awarded to them on 2 March 1895.  David approached the high court to endorse the outcome of the arbitration process.  The matter was heard on 9 March 1895 by the chief justice John Henry de Villiers and Justice Thomas Upington who found for Combrink & Co. and the  £55 000 was endorsed and made an order of the court.  This provided the initial financial basis for the development of their consumer goods empire.

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The CT Headquarters of the ICS.

The second instance was the outbreak of rinderpest, a dreaded disease afflicting cattle that annihilated an estimated 2,500,000 cattle and untold numbers of game animals in the region.  Its spread into South Africa started around 1895.  David’s answer was to import frozen meat from Australia and to distribute it to cold storage facilities to be erected throughout the region.  In order to finance this elaborate scheme, early on in 1897, David and his one brother, Jacobus Graaff started thinking of floating a limited liabilities company. On 4 May 1899, the South African Supply & Cold Storage Co. Ltd. was registered with the nominal capital of £450 000.

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Oxen being slaughtered “roughly” in the field.  They were then hoisted up with slaughter poles and cut into joints for cooking.  (From Ice Cold In Africa)

It allowed David to erect cold storage facilities across Southern Africa and the chance to import vast quantities of meat into the Colony and later into the Union of South Africa.  During the Anglo Boer War, the Imperial Cold Storage and Supply Company won the tender to supply the British forces with meat.  With the refrigerated railway cars that David saw in Chicago when he visited Philip Armour’s packing plant, he was the only firm that had the capacity to take on such an enterprise.  Apart from this, the company became one of the largest meat processing companies in the world.  Our friend eventually sold his shares and the name of the company was changed to ICS during the Great Depression.

The company was in financial trouble by 1934 due to hardship that probably goes back to 1925.  Anglo-American corporation became its biggest shareholder with the total share capital of the company increased to GB£2.2 million (equivalent to £436,000,000 in 2010). The company worked closer and closer with Tiger Oats which was, back then, also a subsidiary of Anglo-American corporation.  (1)

Dawie Hyman

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Dawie Hyman returned to America where he transitioned from working for the Community Chess in Los Angeles and the Twin Cities of St Paul and Minneapolis to establish his own company supplying solutions in the manipulation of data.  After Minette and my visit to New Zealand, we never made it to America as our partners in Cape Town needed our urgent participation in setting up the bacon company and its processing plant. We did eventually make it to Los Angeles many years later, but the objective of the visit was related to further training in areas outside the narrow scope of bacon which consumed me for so many years.

Family

My mom and dad both passed away.  My dad passed away after a motor accident on the way home form a vacation in Natal and my mom, after a long sickbed where she struggled with dementia. My brother, Elmar, became a lawyer and later turned his attention to real estate and the retirement industry.  Juanita kept working as an optometrist, raising Pieter Willem and Handre, their beautiful two boys.  Andre, our older brother left the forestry business and entered the personal protection industry.  Fanie and Luani, Minette’s brother-in-law and her twin sister, continue to live in Cape Town and their two kids, Liam and Luan went on to have successful careers in their own right.

Union of South Africa

The_Times_Tue__Oct_11__1910_
The Times, London, England, 11 October 1910

South Africa became a Union in 1910 and there is talk right now that it will sever its ties with Brittain and form a fully independent Republic.  I have my own mixed feelings about it and see the attitude of many white people as desiring nothing more than to have the independence in order to secure a continuation of slavery just in another disguise.  I remember how this happened with the institution of a system of indenture after slavery was abolished and the Transvaal Republic looked for ways to continue the diabolical practice.  There were reports of slave markets, now in a new form, but effectively the same thing continues to exist in Southern Africa right up to the end of the 1800s. The English waged the First Anglo Boer war based on an assertion that this system was nothing less than slavery by another name.

I insert the opening paragraph of Louis Botha’s speech when we became a Union.  It shows the deeply imbedded racist undertones that existed even in the thinking of people even of the stature of General Louis Botha.

The_Buffalo_Sunday_Morning_News_Sun__Aug_14__1910_
The Buffalo Sunday Morning, 14 August 1910, the opening paragraph of a speech by Louis Botha.

While the Black people got a raw deal, the Union gave unprecedented power to former foes of the British Empire, the Boers.

The_Guardian_Wed__Jun_1__1910_
The Guardian, London, 1 June 1910, a day after the Union was proclaimed.  Celebrating the new political power now largely in the hands of the Afrikaners.

The achievement of the Boer nation was remarkable and this fact should never be underestimated. Here are two more extracts from the newspaper article quoted above, from the Manchester Guardian.  It deals with the fact that a Union was a better option than a Federation and how this gave greater autonomy to the former Boer republics.  It highlights another remarkable fact of the Union of South Africa in the following clipping from the paper.

The_Guardian_Wed__Jun_1__1910_ (2)The_Guardian_Wed__Jun_1__1910_ (3)

This unification of the Afrikaner and English South Africa became a focal point for both Botha and Smuts. The respect from the British that became the basis of their new approach to the Boer nation was built upon respect gained in the Anglo Boer war.  In December 1889, in a piece I wrote from Johannesburg entitled, Seeds of War, I recount my meeting of a Boer called Daniel Jacobs.  One night at a dry riverbed outside Kimberly, he asked me if we could camp together for the night.  He was traveling alone and our transport party provided him with the security in numbers for the night which lone travelers lack.  He was on his way to Johannesburg on government business. I kept contact with Daniel and after the Boer War, he shared the following fascinating account with me which illustrates my point.

He told me the story of one Gustav Baumann who was born on 21 November 1858 in Bloemfontein. His dad immigrated from Germany and was one of the first residents of  Bloemfontein. Gustav was a land surveyor in the Free State and later became Chief Surveyor General. His daughter published a book on her father’s memories after his passing, The Lost Republic: The Biography of a Land Surveyor by Gustav Baumann and Elfrieda Bright. He was a very compassionate person.

He matriculated from Grey College and even though his mother tong was Afrikaans, he learned English while in school.  During the War with England, he fought on the side of the Boers and was captured when Bloemfontain fell in English hands. Pres. Steyn, the president of the Boer Republic of the Free State instructed him to stay behind and to hand the Free State land title deeds to the English forces.

After the war, he met the Boer warrior and folk hero, General de Wet.  He told Daniel, (2) “Meeting old General de Wet after the war, I asked him why, after Bloemfontein and Pretoria had been captured and we knew we could never win the war, he still went on fighting: ‘Mr. Baumann,’ he said, ‘we kept on because we had to knock respect for our people into the British!’  This is exactly the point I am making about the basis for the English treatment of the Boer nations following the war.  It was predicated on respect.  His daughter later wrote about her father (2), “Gustav Baumann, who was an old friend of de Wet’s, and who had the greatest admiration for the old warrior…”

He also made another point of something that my Greta Grandfather, JW Kok referred to which I wrote about in October 1960 where I celebrate The Castlemain Bacon Company from Australia as a producer of some of the finest bacon on earth.  Here, he makes mention of the fact that some of the Boers who were captured early on in the war were accused of “ill-discipline.”  JW Kok was one of those early captured Boers.

de wet et al
Nico Moolamn describes this as “surely… one of the classiest photos in my collection. As dyed by friend Tinus le Roux. For my book “Thank you, general.” Commandant Flip de Vos, Genl De Wet and Veldkornet Alfred Thring at Kroonstad. ABO era.

Gustav Baumann recounts the following about the ill-discipline of the Boers early on in the campaign.  “The lack of discipline, especially in the early stages of the war, was appalling. My brother Herbert was a veld-kornet with the forces investing Kimberley. He was visited by a veld-kornet of the Transvaal Forces. While they were drinking coffee together, a messenger arrived from the Hoft-Commandant (Highest Commandant) for the Transvaler: Commandant Cronje wants to see you at once.” “And who the devil is Cronje to order me about?’ he demanded. ‘Tell him I’ll come when I am ready.’ He finished his coffee and left at his leisure.” He later writes that “…after three years of fighting the men still in the field had learned the art of war.”

Irrespective of the achievements of the Boer, the separation of races and the exploitation of black people and their exclusion from decisionmaking and government never stopped in South Africa but things went from bad to worse when the National Party came to power in 1924 for a short time and again in 1948 which lasted to 1994.  It was in 1948 when a new word was coined to describe the policies of the new government – “apartheid”.  I can see no positive outcome to the scheme and fail to understand how the white population can continue to think that a future is possible that is built upon the exploitation of our fellow human beings and excluding them from determining their own future.  On the other hand, the Boers got a deal, pretty close to what they were fighting for over many years.  South Africa remains a deeply divided land with great opportunities as was proven by David de Villiers Graaff, despite tremendous personal challenges and the diabolical system instituted by the National Government which kept the black man in bondage.

Meat Curing Focus

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Photograph from L V Praagh, The Transvaal, and its Mines, 1906, p.321, of the curing room of a cold storage and butcher’s shop in  Fordsburg, Johannesburg.

My focus remained steadfastly on understanding the chemistry of meat curing to aim Woodys in the right direction. In recent years I became intensely interested in the development of meat curing and preservation in Africa during pre-colonial times.  This is a project on its own to reduce to writing at a future time. When I am done with my work on bacon and the good Lord grants me health and a few more years, I will take this project up for there are amazing tales related to it that have never been told!

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Unie van Suid-Afrika, Departement van Landbou en Bosbou, Hulpboek vir Boere in Suid-Africa, 3de en uitgebreide uitgawe, saamgestel deur D. J. Seymore (Redakteur)
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Unie van Suid-Afrika, Departement van Landbou en Bosbou, Hulpboek vir Boere in Suid-Africa, 3de en uitgebreide uitgawe, saamgestel deur D. J. Seymore (Redakteur)

Bacon & the Art of Living

The letters that follow tell the rest of the story of Bacon & the Art of Living!

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When I’m not working (curing meat) or exploring with Minette, this is my life!

green-previousgreen-home-icongreen-next


(c) eben van tonder

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Notes

(1) In March 1982 Barlow bought a large interest in Tiger Oats and the controlling share in Imperial Cold Storage. In October 1998 Tiger Brands (Tiger Oats Limited) bought out Imperial Cold Storage.  It swallowed up ICS in its own portfolio of brands and subsidiaries.

(2)  The quotes and references all came from The Lost Republic The Biography of a Land Surveyor by Gustav Baumann and Elfrieda Bright which was brought to my attention and quoted by Daniel Jacobs.

References

Brooke Simons, Phillida (2000). Ice Cold in Africa: The History of Imperial Cold Storage & Supply Company Limited. Cape Town: Fernwood Press.

Gustav BaumannElfrieda Baumann.  1940. The Lost RepublicThe Biography of a Land-surveyor.  Bright Faber & FaberFree State (South Africa)