Chapter 5.1 Dr. Ed Polenske

April 1891

My dear Son,

The Noord Nieuwland in Table Bay 1762

Since my last letter about the city and the food, the strange shops, elevated above the streets, the beer and the warm people, I realised that the culture of this amazing land is having just as big an impact on me as what I am learning about the curing of bacon.

After supper, we read together and discuss what was read as is the custom in many households.  The Danes have a  practicalness about them.  They never stop learning and if something works, they adopt it.

Every night after supper, Andreas’ dad reads for us from a book called Foods, written over 20 years ago in the 1870’s by an Englishman, Edward Smith.  He helped me to see the curing of meat as both a necessity and a delicacy.  We cure meats because, for the most part, using modern curing methods, cured meat tastes great.  On the other hand, meat curing was started to impart longevity;  to prevent spoilage.

Back home we are of course well familiar with the value of meat that “last.”  In Europe and England with their growing populations and vast navies which have to be fed, it has been an obsession and a priority to solve the problem of conserving meat for future use.  Edward Smith says in his book that “the art of preserving meat for future use, with a view to increase the supply and lessen the cost of this necessary food (meat), is of very great importance to [England] and all the available resources of science are now engaged in it.” (Smith, 1876: 22)

He lists the main ways that this is being done as “by drying, by cold, by immersion in antiseptic gasses and liquids, by coating with fat or gelatin, by heat, salted meat and by pressure.” (Smith, 1876: 22 – 38)  All have their benefits and disadvantages and I have a feeling that over the years, the technology within any one of these groups may develop, but these broad categories will remain and continue to be available to the public.

Edward Smith says that pork is particularly prized over beef and mutton because of the  “taste, but chiefly perhaps [due] to the universal habit among the peasantry of feeding pigs, which has descended from Saxon times.  Moreover, there is a convenience in the use of it, which does not exist with regard to beef and mutton, for in such localities the pork is always pickled and kept ready for use without the trouble of going to the butcher, or when money could not be spared for the purchase of meat.”  Pigs proved to be an equally prized meat in the new world due to the “ease with which pigs are bred and reared, and the meat preserved, whilst there is great difficulty in obtaining a sufficient number of persons, in a thinly populated country or a small village, to eat a sheep or ox whilst meat is fresh.  (Smith, 1876: 59)

“Bacon is made when cuts from the pig are preserved by salt and saltpeter.”  (Smith, 1876: 64).  This gives bacon its characteristic pinkish/ reddish colour, a nice flavour, and it lasts a long time before it tastes “off”.  This is the kind of things we learn at night.  After a good supper, we discuss what has been read for an hour or two before we all retire to bed.

In the day I work at Uncle Jeppe’s bacon curing factory.  I started working in the curing and spice department where we mix herbs and spices.  Uncle Jeppe is a knowledgeable man and it seems as if he has been around in the meat industry forever.  I have not asked him any question that he did not know the answer to.

Take saltpeter for example. It is the curing salt for bacon which I work with every day in the curing department.  We mix, for dry cured bacon, 1.25 st. (10 pounds) salt, 0.375 st. (3 pounds) of brown sugar, 0.04 st. (6 ounces) of black pepper and 0.02 st. (3 ounces) of saltpeter.  We use 1.25 st. (10 pounds) of this mixture per 12.5 st. (100 pounds) of meat.  (1, 2, 3)

What confused me much was that Trudie’s dad, Anton, also talks about the value of phosphates and saltpeter in fertilizing their fields in the Transvaal.  I have learned in school that saltpeter is one of the ingredients in gunpowder.  I know that the Dutch East Indian Company was created, in part, for the purpose of transporting saltpeter from India to Amsterdam and other European cities like Copenhagen for fertilizer and to make gunpowder. I always wondered if it is the same substance that is used to cure meat and if it is, how can this one substance be useful for such diverse applications.

I asked Jeppe about saltpeter one morning.  He put his arm around my shoulders and told me that there are interesting answers to these interesting questions.  That he hopes I paid attention in chemistry class in school.  For the next week, our Tuesday and Thursday afternoon classes during lunch break were dedicated to saltpeter.

The power of saltpeter is the fact that it contains nitrogen and nitrogen is one of only two elements, with carbon, that can exist in 8 oxidation states.  This means that nitrogen can react in a diverse and complex way and, like carbon, is foundational to all of life.  The two substances that contain nitrogen, most familiar to us, are saltpeter and ammonia.

The nitrogen in saltpeter and ammonia makes it very reactive, giving it an explosive power.  In saltpeter it has a particular effect on blood, explaining the fact that it gives cured meat its pinkish/ reddish colour.  Nitrogen exists in the first place as a gas in our atmosphere and comes into our world in different ways, the most important being through microorganisms with the ability to take it from the air and convert it to food for plants.  The plants take these compounds from the soil and water where the bacteria lives and nitrogen become part of the plant’s structure.  This is why saltpeter is a great fertilizer.

Uncle Jeppe told me that he will tell me the fascinating story of how this was discovered but I had to be patient to hear this another day.  I am here to learn the modern way of curing bacon.  In Europe, I find myself right in the middle of the most up to date and advanced thinking about curing.   A major step has been taken in understanding curing when a friend of Uncle Jeppe discovered something remarkable.

His friend’s name is Dr. Ed (Eduard) Polenske (4), a chemist, working at the Imperial Health Office in Germany.  Jeppe tells me that 1891 will forever be remembered as a watershed year for Woody’s since it is the year I arrived in Denmark and started learning about bacon curing, for the curing industry in South Africa since it is the year when Woody’s took the first steps to excellent bacon in Africa and for the curing industry around the world because of Ed’s discovery.

It is the year when we made a remarkable discovery namely that the brine and cured meat contains nitrite. This is remarkable since we know that saltpeter does not contain nitrite, but nitrates.  They are spelled almost the same, but in reality are two different compounds with different characteristics.  Despite the fact that we do not add nitrite to the meat, how does it get there?  It is also a fact of great concern because nitrite is known to be very toxic.

The next few years will see this knowledge being harnessed by industry and advanced upon by science as they will have to work out if it is indeed the nitrite doing the curing work and if there is any way that this process can be sped up.  The matter of the speed of curing is important because at the moment it takes 21 days for curing to happen.  On farms, this is not a problem, but for a commercial curing operation, it means that you keep large stocks of bacon that are in the process of curing.

Jeppe and Ed met up in Wiesbaden, Germany, earlier this year.  They have been meeting in this ancient spa town in the winter, each year on their annual retreat, since they became acquainted at the  General Congress on Hygiene in Brussels in 1852.  It is exactly the hygienists that Dr. Ed fears will be most concerned about the fact that he found nitrites in cured meat.

Both men attended the conference and struck up a friendship based on their shared passion for good quality and safe meat.  Wiesbaden is famous for it’s hot springs since ancient Roman times and the second shared love between these men, besides meat technology and science, is their love for hot springs.

They have been hosted each year by an equally interesting man, Francois Blanc, at one of his gambling resorts in Wiesbaden.  It is said that he is the man who made Wiesbaden what it is today.  Jeppe describes Blanc as a mighty wizard with an eye, quick to see the possibilities of a situation, with a brain to plan and a hand to execute.  His ambitions and achievements are great across Germany, yet, Jeppe tells me that his tastes are simple.

His cloths do not attract any attention and he wears his spectacles on the tip of his nose.  He does not pay attention to flattery, yet, he is a hard headed, silent man without any enthusiasm and equally without any weaknesses.  He keeps lavish tables, yet he himself eats sparingly.  His wine cellar rivals those of the autocrats in Russia, yet, he himself only drinks mineral water.  He is one of the largest gambling hall owners in Europe, yet, for entertainment he may occasionally play Dominoes and frequently goes on a drive through the countryside with his wife.

It was at their annual visit to Wiesbaden, earlier this year, where Dr. Ed told Jeppe about a monumental discovery.  Dr. Ed is not a huge fan of cured meat since in producing it, nutrition is lost.  This is a time when most families across the world can not afford to eat meat more than two days a week and where most children go to bed hungry, at least a couple of times a week.  In the current world context, Dr. Polenske believes the most important consideration in evaluating methods of preservation is its effect on the nutritional value of the preserved food.

He designed an experiment to study just how much nutrition is lost.  The brine he prepared was a combination of salt, sugar and saltpeter.  (5)  He put this in three jars with three pieces of meat which he sealed and opened again after 3 weeks, 3 months and 6 months respectively.  When he tested for nitrite, he unexpectedly found it in the brine and the meat, despite the fact that he did not add any. (6)

Dr. Polenske told Jeppe that he was not that surprised to find nitrite in the brine since he knew that saltpeter is a compound of potassium and nitrate.  Nine years earlier a drama unfolded with the discovery by French scientists of bacteria that changes nitrate into nitrite and nitric oxide.  In 1882 a team of researchers, Ulysse Gayon from the French commune or town, as we call it, Bouëx in Charente and his 22 year old collaborator, Gabriel Dupetit, from the town of Auch, Gers, coined the term denitrifying bacteria.  This formidable research team went on to make a number of very important discoveries about denitrifying bacteria. (7)

Nitrification starts with nitrogen gas which is one of the most abundant gasses in our atmosphere and through the nitrification process, bacteria create more complex compounds such as nitrate (codecogseqn-2).  An example of nitrification is ammonia (codecogseqn-7) which is changed into nitrite (codecogseqn-5) and finally into nitrate (codecogseqn-2) which serves as the nutritional source for plants.

Denitrification is the reverse where a more complex molecule is broken down to the point where it end up with a simple molecule like nitric oxide (NO) or pure nitrogen gas (codecogseqn-6).  An example of this denitrification is the reverse of nitrification.  This time it starts with a complex compound of nitrate (codecogseqn-2)  which is changed into nitrite  (codecogseqn-5), into nitric oxide (NO), into nitrous oxide (codecogseqn-8) and finally back into nitrogen gas or molecular nitrogen (codecogseqn-6).  Note the gain or loss of the oxygen atom in both processes.

Louis Pasteur, the renowned French chemist and microbiologist urged Gayon to follow what happens with the oxygen of the nitrite ulatized in the process of denitrification.  They heeded his advice paid close attention to this.  They conclusively refuted an old notion that nitrate was reduced through chemical means by the hydrogen, generated during fermentation.  As to the purpose of the loss of oxygen they believed that the bacteria used the oxygen from nitrogen for the combustion of organic matter to generate  CO2. (8)

Based on their very thorough work, Dr. Polenske believes that nitrite is present through this process of denitrification of nitrate by bacteria.  He expect there to be much public concern following his discovery since nitrite is seen as a poison.  (9)  There is a constant battle from farmers to keep their cattle away from water that has nitrite and in every major newspapers, in every town and city, the nitrite levels in the town’s drinking water is published every week so that citizens know to avoid it.  Science will have to work out over the years to come exactly what the nitrite is doing in the brine and what is the element that is causing the meat curing.  Is bacon a food that should be allowed at all?  The monumental nature for me is however not the fact that nitrite itself was discovered in the brine, but that one more element of what makes up a curing brine has been identified.  Especially one that science did not know to be present.  Unless we know every element present in the brine, we will not be in a position to manipulate the process or improve on it.

Tristan, there is another important point in this story that strikes me.  Right at the start of this journey, I realised that what we are discovering is much more than simply learning how to cure bacon.  This journey back to the lands of my forefathers is a big deal!  Bacon is in the centre of scientific research of Europe, America and the United Kingdom, and the combined scientific focus of these countries are directed at unlocking its secrets which are bound up with that of agriculture and superior technology in warfare.  But besides these, there are the many human stories.  Real people who each contribute to small parts of a very large jigsaw puzzle that is coming together.  They teach us about life.

Within the same year of publishing a major paper on denitrifying bacteria by Gabriel and Ulysse, tragedy struck.  The young Gabriel Dupetit’s tragically ended his own life.  He traveled to the Italian city of Savano and booked in at the Albergo Svizzero under the false name, Gaston Dunault.  Overcome by anxiety of all sorts, on the evening of 28 December 1886, he injected poison into himself.  He was discovered, barely alive and despite much effort to save his life, he passed away on the morning of the 29th.  He left a note in French explaining some of his worries.  The use of the false name was done to hide his identity and spare his parents embarrassment.

I am humbled and saddened by this story.  His work directly contribute to our quest of understanding bacon and still, his death reminds me that our lives are bigger than our goals and dreams.  Despite our ambitions, we must pay attention to each sunset and sunrise and never make the mistake of thinking that achieving goals define us.  A man who got this balance right, I believe, is Francois Blanc who seems to find fulfillment in small things, despite his success.  His success does not define him.  He finds the greatest fulfillment in the ordinary in life.  In this, bacon and life becomes almost inseparable and I am never sure when I stop learning about the one and start learning about the other.

At the moment, we are not certain what the role of nitrite plays in meat curing.  We don’t understand any of the process, but identifying the different elements in the brine, including microorganisms, nitrate, nitrite, salt, potassium and sugar is the basis for understanding the process and should open up the possibility to do it faster and better and safer without loosing quality.  I would love to take back to Cape Town a curing method where curing can be done in a shorter time than 21 days, yielding a product that tastes just as exquisite as Wiltshire cured bacon.

With these lofty goals then, my dear Son, it is time for me to go.

Be well my boy!  Take care of Lauren and Minette.

Lots of love from Denmark,

Your Dad.


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(c) eben van tonder

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(1)  “St” is the abbreviation for “stone.”   Until as recent as the Second World War, the Smithfield market in London used the 8 lb to a stone measurement. (hansard.millbanksystems)

The stone weight differed according to the commodity weighed.  Animals were weighed in 14 lb to a stone before they were slaughtered and once slaughtered, the carcass and meat would be sold in 8 lb to a stone measure.  Spices were also sold in 8 lb to a stone weights.  (Newman, 1954)

(2)  A survey was done in the US in the 1950’s to determine the most common brine mix used for curing bacon at the time. (Dunker and Hankins, 1951: 6) Even though it is 60 years after this letter was presumably written, I include it since methods and formulations in those days seemed to have a longevity that easily would have remained all those years later.  The survey was also done among farmers, in an environment where innovation are notoriously slow.

(3)  How salty was this bacon in reality?  The recipe is used by most US farmers by the 1950’s was 10 lb (4.54kg) salt, 3 lb (1.36kg) of brown suger, 6 ounces (170g) of black pepper and 3 ounces (85g) of saltpeter.  10 pounds (4.54kg) of this mixture per 100 pounds (45.36kg) of meat.

The total weight of dry spices is therefore 6.07kg of which salt is 74% or  3.4kg.  This was applied at a ratio of 3.4kg salt per 45kg of meat or 1 kg salt per 13 kg of meat.  Not all salt was absorbed into the meat, but the meat was regularly re-salted over the curing period which means that this ratio would be applied many times over before curing was complete.  Compare this with the salt ratio targeted by us in 2016 of 25g per 1kg final product, this means that the bacon made with this recipe would be extremely salty, irrespective of the use of sugar to reduce the salty taste.  The bacon would have to be soaked in water first to draw out some of the excess salt, before consumed.

(4)  Eduard Polenske (1849-1911) was born in Ratzebuhr, Neustettin, Pommern, Germany on 27 Aug 1849 to Samuel G Polenski and Rosina Schultz. Eduard Reinhold Polenski married to Möller. He passed away in 1911 in Berlin, Germany. (Ancestry.  Polenske)

The Imperial Health Office was established on 16 July 1876 in Berlin,focussing on the medical and veterinary industry. At first it was a division of the Reich Chancellery and from 1879, fell under the Ministry of the Interior. In 1879, the “Law concerning the marketing of food, luxury foods and commodities” was adopted, and the Imperial Health Office was tasked with the responsible for monitoring compliance with it. Established in 1900, the Reichsgesundheitsrat supported the Imperial Health Office in its tasks. (Wikipedia. Kaiserliches Gesundheitsamt)

(5)  Brine is a solution of salt in water.

(6)  Qualitative and quantitative techniques for measuring nitrite and nitrates in food has been developed in the late 1800’s.  (Deacon, M;  Rice, T;  Summerhayes, C,  2001: 235, 236).  The earliest test for nitrites is probably the Griess test.  This is a chemical analysis test which detects the presence of organic nitrite compounds. The Griess reagent relies on a diazotization reaction which was first described in 1858 by Peter Griess.

Schaus and others puts the year of the discovery by Griess as 1879.  According to him,  Griess, a German Chemist used sulfanilic acid as a reagent together with α-naphthylamine in dilute sulfuric acid.  In his first publication Griess reported the occurrence of a positive nitrite reaction with human saliva, whereas negative reactions  were consistently obtained with freshly voided urine specimen from normal individuals.   (Schaus, R; M.D. 1956:  528)

(7)   Gayon and Dupetit’s discoveries include the following:

  • they demonstrated the “antagonistic effect of heat as well as oxygen on the process.”
  • “They also showed that individual organic compounds such as sugars, oils, and alcohols could supplant complex organic materials and serve as reductants for nitrate.”
  •  In 1886 they reported on “the isolation in pure culture of two strains of denitrifying bacteria.”

(Payne, W. J..  1986)

(8)  In reality, the key to understanding the function of the utalization of the oxygen atom is understanding cell respiration.  The purpose of cell respiration is the formation of ATP.  The organism needs nutrients for respiration which is obtained from sugar, amino acids, fatty acids and an oxidizing agent (electron acceptor), oxygen (codecogseqn-9).  Now, in environments where oxygen is depleted (where the rate of oxygen consumption is higher than oxygen supply, the bacteria respire nitrate.  The nitrate serves the purpose of the terminal electron acceptor, a function which is better performed by molecular oxygen, if it is available.  It is not only nitrite that is used by microorganisms in respiration when molecular oxygen is depleted.  Other electron acceptors are sulfate, iron and manganese oxides.

(9)  Dr Ed Polenski’s findings has been published in “Arbeiten aus dem Kaiserlichen Gesundheitsamte , 7. Band, Springer, Berlin 1891, S. 471–474” (


Asheville Citizen Times (Asheville, North Carolina), 20 August 1895.  All information on Francois Blanc was from an article on page 3.

Dunker, CF and Hankins OG.  October 1951.  A survey of farm curing methods.  Circular 894. US Department of agriculture

Jones, Osman, 1933, Paper, Nitrite in cured meats, F.I.C., Analyst.

Drs. Keeton, J. T.;   Osburn, W. N.;  Hardin, M. D.;  2009.  Nathan S. Bryan3 .  A National Survey of Nitrite/ Nitrate concentration in cured meat products and non-meat foods available in retail.  Nutrition and Food Science Department, Department of Animal Science, Texas A&M, University, College Station, TX 77843; Institute of Molecular Medicine, University of Texas, Houston Health Science Center, Houston, TX 77030.

Payne, W. J..  1986.  1986: Centenary of the Isolation of Denitrifying Bacteria.

Smith, Edward.  1876. Foods. D. Appleton and Company, New York.

Schaus, R; M.D. 1956.  GRIESS’ NITRITE TEST IN DIAGNOSIS OF URINARY INFECTION,    Journal of the American Medical Association.

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