Chapter 13.06.00: Harris Bacon – From Pale Dried to Tank Curing.

Introduction to Bacon & the Art of Living

The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting.  Modern people interact with old historical figures with all the historical and cultural bias that goes with this.


Harris Bacon – from Pale Dried to Tank Curing!

14 April 1892

Dear Lauren, Tristan and Oscar,

We are finally where we wanted to be, just over a year after I left the Cape of Good Hope. The vision is to not only produce bacon but the best bacon on earth. Last week was maybe the most monumental week for our venture. Here is how the week unfolded.

Harris Bacon – Best on Earth

Harris

Harris bacon is being hailed as the best bacon on earth, a designation that I aspire to for our bacon in Cape Town. It was the combination of stitch pumping and hot smoking that enabled the Harris brothers to reduce the brining and equalising steps that created sweet cured bacon. The net effect of stitch pumping and hot smoking made it possible to effectively cure meat with far less salt. This happened in the early 1840s. When refrigeration was set up through ice houses in the mid-1850s, it rounded off the system by allowing even less salt and saltpetre to be used and it stabilised the overall new system of mild curing.

The mildly salted, sweet-cured bacon was a huge success. The 1888 publication of Wyman’s commercial encyclopedia of leading manufacturers of Great Britain, by Wyman and sons, says that the Great Western Railway Company’s mainline was opened, passing through Chippenham [and saw that railway facilities were brought] within six miles of the town; this, however, was not near enough, as the requirements of the bacon trade, for carriage of both pigs and bacon, rendered it most important that the town should be placed in direct railway communication with all parts of the country. The demands of the bacon industry led to the building of a branch line from Chippenham to Calne in 1863; and at the present time, many tons of goods are despatched by rail daily from Messrs. Harris & Sons’ factory alone. The bacon manufactured by this Firm is supplied, through their agents, to the households of Her Majesty and H. R. H. the Prince of Wales, the Houses of Parliament, &c., and is not only sent throughout England, Scotland, and Ireland, but finds its way to the continent of Europe, India, China, the Cape of Good Hope, Australia, New Zealand, America, and numerous other distant places. For keeping in hot climates, the bacon is extra-cured and smoked.

By the end of the century, the Calne factories supplied the principal Transatlantic, Pacific, and Far Eastern steamship lines. There is a lot of competition from the colonies, especially cheap American bacon but nobody was able to compete with Harris on quality. The British Journal of Commerce wrote in January 1889 that Calne was “the chief seat of the bacon-curing industry of England.” It was said that Harris produces more bacon than any other four or five curers in England together. Between 2,000 and 3,000 pigs are slaughtered each week and over 200 workmen and 30 clerks are employed. (British-history)

Pale Dried Bacon

William Oake invented the Mild-Cured system of bacon production. Mild-cured bacon was pale bacon which resulted from the use of Sal Prunella as the curing agent which contained sulphate. The sulphate interfered in the curing process by eliminating the bacteria that were relied on to convert the saltpetre which was also used to nitrite. The result was well-preserved meat, but the appearance was pale as no curing took place. The prolific Dutch curer lived in London as a young boy in the middle 1800s and reported that he remembers great efforts being expended to convince the British public that pale bacon represented healthier bacon. He explains the reasoning that was given to the public as follows from an interview he did in New Zealand. He said, “Under the old method the salt and the albumen contained in the pork combine and make a pickle which runs away in the process of curing, taking away all the nutriment from the meat, and leaving only the fibrous system and the fat. The saltpetre also acts chemically upon the fibrous tissues of the meat, giving a high colour, unnatural to the flesh, and this high colour was often mistaken for goodness by the uninitiated. After this fact became generally known, scientists, foremost amongst whom was Professor Liebeg, set about to remedy the evil, so far as beef was concerned, by preserving in tins instead of salting, and also by extracting the albumen from the beef and bottling it. This process, of course, it was impossible to apply to bacon, because at that time, pigs were fed to such a weight that by far the greater proportion of the carcase was composed of fat, and as fat is impervious to saltpetre and also to the action of salt, people continued to preserve pig’s flesh in the old-fashioned way, and the world trade in the pig line was not interested to any extent in the new discovery, and bacon and ham still continued to be used simply as a relish more than a sustaining food.” He said that the new system invented by William Oake in Ireland had the effect that bacon and hams treated by his process, “although thoroughly cured with the very essence of salt, still retained all the albumen originally in the meat, although it would not, of course, be salty to the palate. The lean instead of being a secondary consideration, as under the old process, became at once the nutritious delicacy it was intended by nature to be.” (Interview with Aron Vecht, 1894) The science is of course not accurate on this point, but it reveals the basis for why they believed the pale bacon to be healthier.

It was undoubtedly in response to this that the principal bacon produced in England at the time, the Harris operation from Calne developed their own pale versions a progression of their sweet-cured bacon. This happened under John Harris. Let me recap what Mr Smith told me a few weeks ago at Bowood, which I reported to you in my previous letter when he defined sweet cured bacon, pioneered by Harris in the 1840s. It is bacon that is cured with less salt and saltpetre, with or without the addition of sugar and hot smoked immediately after curing without a drying or equalising step.” Pale-dried bacon is produced in exactly the same way as sweet-cured bacon. The difference is that after brining when sweet cured bacon is hot smoked, pale dried bacon is not smoked at all. Instead, it is only dried or heat set.

Below are two pieces of equipment from Germany that illustrates the difference between sweet cure and pale dried bacon. On the first machine, the stove and the smoking chambers are separated so that the meat can either be heated on one side or hot smoked on the other. To produce sweet-cured bacon, the meat will be placed on the hot smoking side, and if you want to produce pale dried bacon, it would be hung in the chamber where only heat is applied and no smoking. Notice piping from the oven at the bottom where the smoke and heat are generated bypass the chamber that is open in the illustration – the chamber on the right in the picture below. Only heat will reach this section as there is a separation between the two chambers to shield the smoke from the pale dried variety.

Smoke oven 2

By contrast, the illustration below is only intended for sweet-cured bacon since no option exists in its design for the smoke to bypass the meat. Smoke and heat will pass through the chamber and hot smoke the meat, resulting in mild cured bacon only.

Smoke Oven

The “pale” in the naming of the bacon, therefore, refers to the fact that instead of a golden brown colour of the bacon after hot smoking, the bacon will be pale since it is only heat dried as opposed to smoked. Another reason for its pale appearance is that during the cooking step, the proteins would denature and the bacon would be paler. From there the term pale dried bacon. It may look as if Harris did not understand the benefits of smoking other than drying it. This will however be a wrong assumption. They recognised that smoking was, in the first place, done for drying the meat, which they now achieved without smoking. The smoke itself contributed nothing to the drying. This was all done by the application of heat! It was customary for bacon to be shipped “green” to clients and once it arrives at its final destination, to be smoked there before it was sold. Instead of selling it green, hot drying would be better since the all-important drying is achieved and smoking was, in any case, done on the other end, why not omit the smoking in the initial production completely?

Harris constructed large, specially designed drying rooms for this and the German machines featured above are later small-scale designs to achieve effectively the same thing. Harris, who invented this process, however, built specially designed rooms. This room is equipped with a line of pipes on which are cast gills for radiating the heat. These pipes are laid around the room and are connected to a supply of steam. They radiate four times more heat than can be derived from plain steam pipes. The heat required in the drying room is from 80 deg F (27 deg C) to 95 deg F (35 deg C) at which temperature most goods will dry economically. The bacon is kept in the drying room for around 18 hours with a weight loss of only about 6% to 8% which is remarkable! Some of the bacon is smoked afterwards before it is sold, but this leads to unacceptable weight loss. (Sutherland and Sutherland)

John Harris has been involved in several court cases this year where imitation pale dried bacon was being sold as Wiltshire bacon. I paste a clipping from Wrexham Advertiser (3 March 1894) that reports on John’s appearance in court to defend their invention.

Court case

Wrexham Advertiser, 3 March 1894.

Mild cured bacon, which I already wrote to you about in the greatest detail (Chapter 09.01 – Mild Cured Bacon) is specifically the Irish system, invented by Willian Oake from Northern Ireland, adopted in Denmark and practised there almost exclusively. The key distinguishing feature of this system that sets it apart from sweet-cured Harris bacon is the reuse of the old brine or the application of a live brine system as it would later be referred to. Harris made fresh brine for every production cycle, and Oake’s system did not. When they stopped using Sal Prunella, the bacteria in the brine containing the nitrates, were reduced through bacterial action into nitrite. Jeppe speculated, based on the observations of Dr Polenski, that it was the nitrite that is responsible for the quick curing of the meat. This gave another improvement in both the speed of curing as well as its consistency which Harris, at this time, has not happened upon.

Other features in producing sweet-cured Harris bacon which is similar to the mild cured system of the William Oake include the initial extraction of meat juices after the bacon sides have been cut, the light salting of the flitches when they are stacked in the curing tubs, the emersion in cover brine and the second stage drying of the sides and light re-salting after pickling following the same method of re-packing or re-stacking the sides in the drying room as is done in the curing baths or tanks. Components of the total system have been in use by many, and Harris already had most of the features included in their production of sweet-cured bacon. William Oake’s mild curing system brought all the different aspects together in one industrialised unit along with his very specific requirement for using Sal Prunella.

Pickle Pump 2

The Deal -> Trade the Danish Secret for Machines and Factory Plans from Harris (5)

Yesterday, 13 April 1892, was my birthday. John Harris invited Minette and me to his home for supper. His wife baked me a beautiful cake with candles that don’t go out when you blow them. We had great fun, singing and laughing. I enjoy their company! After supper, we went to his reading room, where we had a nightcap when he asked me directly about the Danish system. We came to respect each other, and he had a proposition for me. They will show me their complete system of mechanisation and exactly how pale dried bacon is made if I am willing to teach them the Danish system, as he calls it. Instead of moving from department to department and spending time with the different supervisors, he will assign me to work directly with his plant manager and chief engineer.

I was thrilled! It will allow me unprecedented access to their plant. He is even willing to share engineering drawings of machines with me so that we can either have the machines built in Cape Town or, if it cannot be done there, commission the machines to be built in England. They immediately started to take me through their plant in a very methodical way. The first order of business was to show me how they produce pale dried bacon. Whenever all the technicalities got too much for Minette, she would excuse herself and retreat to “an excellent [new] institution in the Harris factory [namely a] reading-room, which is well supplied with books and daily papers for the benefit of the employees. (Wymans)

Upon my return from the first factory tour, Minette and I joined John Harris for lunch in his office, where I gave him a brief outline of the Danish system. John listened attentively as I explained the time benefit of mild curing, and from what he had already started to show me in exchange for this information, I can tell that he really wants the information.

It is amazing to think, Oscar, that our quest will improve the way that the best bacon in the world is produced when we combine the sweet curing and pale dried systems of Harris with the mild-cured bacon of William Oake. Could you ever imagine that we, all the way from Africa, would play such a pivotal role in the global bacon trade? It was Friday and John asked me, starting on Monday, to work with his team of engineers and take them step by step through the complete Danish system.

pickle pump 3

Wiltshire Bacon Cure – Tank Curing

When I arrived at work on Monday, a small army of scientists was awaiting me, and we started working on the transfer of information and incorporating the Danish system immediately. It was clear that the English were not interested in simply copying the system but to integrate it into their existing system and to improve on it. 

It was a momentous week as the scientists from Bristol that assisted us worked through the process very systematically. In the end, my own input was minimal, restricted to pointing out some practical methods from what I learned in Denmark. The heavy lifting was done by experts in microorganisms and chemistry. By the end of the week, this has been achieved. (12)

pickling tank

Schematic Representation

Let me begin by giving you a schematic representation of the system that was eventually developed.

Diagram from Sutherland & Sutherland (1995). Hot smoking was also used. Most bacon flitches were wholesaled and sliced by the clients as vacuum packing was not invented yet. Smoking continued to be done mainly by the clients.

Meat Selection

The first thing they showed me was the importance of the right meat selection. This lesson I first learned on Stillehoogte from Oupa Eben. Happy pigs make for good bacon! The thing is that if the carcass is going to be chilled immediately after slaughter, it is important to drop the temperature of the warm carcass as quickly as possible to prevent damage to the meat from lactic acid. It normally results from pigs that are stressed before they are killed. It is, therefore, important to rest the animals before slaughter. This condition mostly afflicts pork and is called PSSE, which stands for pale, soft and exudative meat. The meat becomes soft, pale and mushy, and it cannot hold the brine. It is completely unsuited for curing. The other condition that can arise is dark, firm and dry meat (DFD) which normally affects beef, but also occurs in pork. This is characterised by meat with an ultimate pH of above 6.2, and even though it is not as ineffective for curing, is still undesirable. The meat fibres, in this instance, are enlarged. It holds the brine very well; the brine cannot permeate the meat thoroughly, resulting in uncured patches in the meat, which are then the places where spoilage sets in. It occurs because glycogen is exhausted before slaughter, and to prevent it, the pigs must be well-rested before slaughter. In Northern Ireland, they feed the pigs 1kg of sugar about 16 hours before slaughter which seems to prevent this. One downside to this is that it affects the quality of the liver, which is a sought-after by-product. (Sutherland and Sutherlans, 1985)

Remember that in my previous mail, I told you that in the sweet-curing system of Harris, the meat is injected before rigour mortis sets in? It became customary at the Harris factory to hang the sides till the next morning in the cold rooms before further processing started. This meant that brine was not injected into warm meat, but after rigour set in. Because the problem of both PSSE and DFD only started becoming a big headache for Harris after the cold-rooms were installed and when further processing only started a day later, post-rigour, we can conclude that an application of injection brine pre-rigour prevents the onset of these conditions. In an industrial setup such as Harris, the benefit of not having the pressure to work the meat on the day of slaughter outstripped the advantages of managing DFD and PSE through the application of pre-rigour brining. (Sutherland and Sutherlans, 1985) I will return to this when I discuss brining because, in Denmark, they are experimenting with exactly such a step which they re-introduced based on the advantages of injecting the meat before rigour sets in.

Preparation

The pig sides are cooled after the backbone is removed, either at ambient temperature or in a chiller. “After cooling, the sides are trimmed.” Trimming involved removing the fillet (the psoas major muscle along the central spine portion), the shoulder blade bone (the scapula), and the pelvic bone (the aitch bone). The sides are now placed in a curing cellar (room temp of between 3 deg C to 7 deg C). (1) (Lawrie, R. A.; 1985)

Refrigeration Machine

Curing

– The Brine Makeup

Curing will take place in four stages. First, the brine is pumped into the sides using stitch pumping or a single-needle hand injector. The salt concentration in the brine must be between 25% and 30%, 2.5% to 4% potassium or sodium nitrate (saltpetre) and 0.5% to 1% sugar. Between 18 and 25 injections are required, most in the gammon region. The total weight of brine injected is about 5% of the weight of the side. 1kg then became 1.05kg injected. (Lawrie, R. A.; 1985) The overall injection across the side can actually be as high as between 8% and 10%. The loin is injected less, and the belly, not at all. The pressure of the injector is set at no higher than 60lb/in2 or 4 bar.

– Dry Salting with liquid Brine Immersion

The sides are either sprinkled lightly with dry salt and placed in a tank of brine, stacked about 12 deep and tied down. If a wet cure is used, the sides are covered with a mix of salt and potassium nitrate in a ratio of 10:1. Liquid brine solution is run into the tank, and the sides remain submerged for between 4 and 5 days. (Lawrie, R. A.; 1985)

Composition of injection and immersion brine in Wiltshire curing brines (%, w/v) From Sutherland & Sutherland, 1995.

pickle pump 4

– The Reuse of Old Brine

A distinct feature of the system remains the reuse of the old brine. John Harris already understood this. It is at this point that all the training by Andreas and Uncle Jeppe paid off. I understood enough about the newly emerging science of microorganisms to know that I could suspect that sal prunella may have a detrimental impact on the curing process. I suspected that the sulphites either eliminated the microorganisms or, in some way, restricted their ability to reduce the saltpetre to nitrites. These notions were confirmed by the scientists present in the working group. If the live brine system was used without the addition of sal prunella, they speculated that nitrates would be reduced to nitrites in the old brine where bacteria remove one oxygen atom from the saltpetre molecule. The makeup of the tank pickle was set at between 20% and 28% salt (sodium chloride) and 3% – 4% saltpetre (sodium nitrate) when it was first prepared. In order to effect the reduction of the nitrates to nitrites, the brine is seeded with the specific microorganisms (6) that are responsible for the reduction. The “seeding” is done from microorganisms in the old brine. Such seeding has, therefore, the dual function of introducing reduced nitrites to the new brine and microflora responsible for the reduction. (Lawrie, R. A.; 1985)

– Its Roots

The earliest mention I could find of the reuse of old brine comes from the 1830 edition of The Complete Grazier. The report says that wet cure is more expensive than dry cure unless the brine is re-used. First, the meat is well rubbed with fine salt. A liquor is then poured over the meat, and “though the preparation of such brine may, at first sight, appear more expensive than that prepared in the common way, yet we think it deserves a preference, as it may be used a second time with advantage if it is boiled, and a proportionate addition be made of water, and the other ingredients above mentioned.” (The Complete Grazier, 1830: 304)

The concept of reusing the power of old brine is something that has been known in England since at least the 1820s. The edition of the Complete Grazier referred to is from the 5th edition, which means that by this time, the description may already be five years old if it appeared in the 1st edition. Notice the comment that the brine can be used “a second time.” It seems that the practice of reusing old brine in England in 1820 and 30 was a far cry from the complete system of William Oake from the same time in Ireland, where the multiple (continuous) re-use of old brines was part of Oakes complete mild cured system.

The reuse of the brine is a concept that possibly has its roots in Westphalia in, Germany. William Youatt, who compiled the Complete Grazier repeats this process in his 1852 work, Pigs: A Treatise on the Breeds, Management, Feeding and Medical Treatment of Swine; with directions for salting pork, and curing bacon and Hams. He says that “the annexed system is the one usually pursued in Westphalia : — ” Six pounds of rock salt, two pounds of powdered loaf sugar, three ounces of saltpetre, and three gallons of spring or pure water, are boiled together. This should be skimmed when boiling, and when quite cold poured over the meat, every part of which must be covered with this brine. Small pork will be sufficiently cured in four or five days; hams, intended for drying, will be cured in four or five weeks, unless they are very large. This pickle may be used again and again, if it is fresh boiled up each time with a small addition to the ingredients. Before, however, putting the meat into the brine, it must be washed in water, the blood pressed out, and the whole wiped clean.”

Youatt repeats the re-use of the brine in the publication just mentioned. He writes, “In three weeks, jowls, &c, may be hung up. Taking out, of pickle, and preparation for hanging up to smoke, is thus performed: — Scrape off the undissolved salt (and if you had put on as much as directed, there will be a considerable quantity on all the pieces not immersed in the brine; this salt and the brine is all saved; the brine boiled down [for re use].” Notice that his 1852 description is far more “matter of fact” and he does not go into all the explanations and caveats he did in the 1830 description.

The incorporation of this facet of curing brines was undoubtedly not as developed as it was in Ireland in the 1820s and 30s. John Harris did not elaborate exactly on when he became aware of the system. I stumbled upon information a day or two later, which made it clear to me that by 1861 the concept was thoroughly entrenched in the English brining establishment. This fact came to me through the curing method of Auto Curing Bacon.

– Maintaining Adequate Levels of Nitrites and “Cleaning” the Brine

Let us return again to the concept of the reuse of the brine. In doing so, I also address the issue that I believe was misunderstood by the wider science community, namely the role of the albumen. The meat juices (protein) that leached from meat that was previously immersed in brine are used with the new brine. This that tank curing is, in effect, the Danish system they got from the Irish.” The difference is that the old curing system used by the Irish and the Danes relied on Sal Prunella. To think that albumen did not enter the cover brine was incorrect. In the system, the albumen would, in reality, take on an entirely new role as feeding the bacteria to enable them to perform the function of reducing the nitrates to nitrites. The liquid form of proteins which scientists refer to as peptone, is essential for the effective development of a bacterial colony in the brine to cure the meat and give the bacon even more of a unique flavour.

The amount of nitrite in the brine is managed by adjusting the salt (sodium chloride) concentration in the brine. (2)  (Lawrie, R. A.; 1985) The basis of this approach is the fact that the nitrite level in the brine remains at the same level, provided that the salt concentration is maintained at approximately 22%. If the salt concentration increases, the nitrite level tends to decrease. At lower salt levels, the nitrite level may increase. No studies have unfortunately been done to date on the bacterial levels in these brines. It will then seem as if salt concentration levels impact the nitrite level in the brine. Other factors are the proportions of saltpetre and nitrate-reducing bacteria in the flora as well as the enzyme activity of these organisms, the amount of nitrite taken up by the meat and the amount destroyed through chemical means. (Mrak,1953)

The most effective method to clean the used brine at the end of the production day is filtration. The NaCl levels, as well as saltpetre levels, are adjusted back to the required levels. Temperature of a maximum of 4 deg C must be maintained. Keep in mind that the salt (NaCl) levels will fall by around 2.5% and the volume by around 7% due to leakage of the brine from the meat. New, fresh brines can be added, or HCl can be used to stabilise the brine at the end of the day, even though this is not always effective. Also, remember that circulating the brine continually during injection is not always practised for a good reason. (Sutherland & Sutherland, 1995)

Ingram (1951) made the following comments about ham and gammon taint. “A ham properly cured without injection, and internally ‘sterile,’ can be made to keep almost indefinitely. The bacteria injected into gammons slowly cause internal off-flavours even in cool storage. For long storage, it would seem wise to sterilize brine used for injection, and the addition of acid might be beneficial.”

– Acidifying Bacon?

Lactic acid in the muscle is beneficial for curing as well as for micro-control, and many brines are slightly acidic in any event. The question then comes up why don’t we acidify the brine? It is a logical question and one that I asked right at the start of working in Uncle Jeppe’s factory in Denmark. (10) What we discovered was that when we used a weak acid, in our case acetic acid, the buffering capacity of the brine increased. We very soon had to use a large amount of acetic acid to adjust the pH. Thinking about it now, I realise that it would have been far better to use hydrochloric acid since excess chloride ions have no buffering action. The pH we aimed for was 4.5, and Jeppe doubted if it was typical of curing brines and the project was never completed. I heard subsequently that work was done where brine was buffered to a pH of 3.4 using a combination of citric acid and disodium phosphate. Meat itself is a powerful buffer. Adjusting the pH of the meat by preslaughter treatment, as we already referred to in feeding the pigs sugar, may yield better results than trying to do this post-slaughtering with acid brines. (Mrak,1953) It remains somewhat of a question. I am a great fan of acidification and will continue to return to the topic.

Alternative to Curing Option

Remember the comments I made in my previous mail where I stated that the existence of refrigeration brought about changes in the meat if the animal is worked cold compared to when the meat is still warm? In general, diffusion of the brine through the meat happens a lot faster if the meat is warm compared to when it’s cold. This is why hot smoking contributes materially to this process. The downside is that there is a greater risk of microbial spoilage when the meat is warm. The way to overcome this is through very strict procedures. One way to still use the advantage of the warm meat is to inject brine using stitch pumping before rigour mortis sets in – while the meat is still warm. The result will be that the cure will spread rapidly through the meat, and colour development will be faster. In addition, the overall yield will be better, and cooking loss will be less. It is possible to now replace the emersion brine with dry salting only and sides can be hung quickly and individually, which allows the side to be chilled quickly after this operation. It has been shown in some factories in Denmark where this has been tested that good bacon can be made in this way in as little as 5 days. (Lawrie, R. A.; 1985)

Maturing

The sides are placed in a maturing cellar for 6 to 7 days. Maturing days for as low as two days have been used in Denmark, but the curing was not as good. Many processors there report good curing in between 4 to 5 days. This was another major progression of the sweet-cure process used in the Harris factories since the 1840s. The temperature was kept between 3 deg C and 4 deg C, as was the case in the brine cellar. The goal of this step was to diffuse the brine of sodium chloride, nitrate, and nitrite throughout the meat. (Lawrie, R. A.; 1985) It took me some time to properly describe this step to the Harris engineers since the maturing step as I learned in Denmark, should not be confused with the maturing step in a dry-cured system as it is not expected to yield any chemical changes in the meat.

It is important to construct the pallets used for stacking the bacon during this stage from steel. (7) Wood should be avoided due to the likelihood of contaminating the meat again. The relative humidity should be kept at between 82% to 85%. One way that relative humidity can be achieved is to keep the floor of the maturing room wet with brine. Since extensive microbial growth can occur during this step, they may want to reduce the time the bacon spends maturing to as low as two days.

There is a school of thought that during maturing, bacon flavours are produced through the action of bacteria. This may or may not be the case, and if bacon flavours develop as a result of long maturing times, the question still remains if the public will notice these changes. Many people swear by it, and others can not detect any difference between bacon where long maturing times were used and those where it was not used. This will remain a subject to be studied in the future. Where long transport times are envisaged, maturing can be done en-route. (Mrak,1953) As I already mentioned, it’s best not to expect any positive flavour development in the meat quality to take place during this step.

Smoking

Most of the cured meat was un-smoked (green) but some would be smoked for between 2 and 3 days, normally for local sales.  The traditional Wiltshire process yielded well-cured bacon in anything between 10 and 21 days. (Lawrie, R. A.; 1985) (8)

It has been shown that smoking reduces the number of bacteria present on bacon considerably. It is estimated that it is able to double the storage life of bacon. On the other hand, smoking seems to increase the mould formation on bacon. (9) As storage temperatures decrease and salt levels increase, the time is increased before slime formation on the surface of bacon can be noticed. If the final pH of bacon is reduced from 6 to 5.6 the microbial flora in bacon drops significantly. (Mrak,1953)

harris 4

Packing and Shipping

Bacon is baled for shipping. Cloth that is wrung out of hot water or dry sterile cloth is used to wipe dirt, salt, bits of fat and bone dust from the sides. During sea voyages, the bacon is packed under refrigeration, and if the sides have been wiped well, this also removes a lot of the bacteria, and the onset of slime is retarded. (Mrak, 1953) When slime formation occurs, one can normally wipe this off unless the flavours have been affected. Usually, this does not happen unless yeast develops and leaves a yeast flavour on the bacon. In this case, smoking should mask any off flavours. For this reason, most Wiltshire sides are packed unsmoked and smoked at the final destination. (Mrak,1953)

Mould is a different story, and the taste can normally not be disguised or removed by washing. This is why borax was originally used on Wiltshire sides as a preventative measure and when shipping times were delayed, and long-term storage was required. Borax prevents mould formation, but it may encourage bacteria growth. Boric acid has the opposite effect, namely removing bacteria but encouraging mould formation. The reason for this is probably the change in the surface pH. (Mrak,1953)

Storing temperature at -15 deg C prevents large ice crystals from forming, and at this temperature, it can be kept in a good state for 3 1/2 months. Eventually, all bacon will spoil if stored for too long. The fat of bacon turns yellow as it becomes rancid. This happens even under frozen storage. (Mrak,1953)

Smoked bacon keeps longer in both the frozen and the unfrozen state due to the well-known anti-oxidant effect of smoke. The deeper layers of fat where the smoke did not rich remain unprotected and are prone to spoilage. (Mrak,1953)

It is done! We effectively progressed mild curing with C & T Harris. Tank curing is then the English modification of the mild curing system of William Oake and would become known as Wiltshire curing. A question immediately came up as to why Harris did not get this from Ireland directly much sooner, especially because many wealthy families from Cale were involved in the pork trade from Ireland. Lord Lansdown was a landowner in Ireland, as were many of his neighbours. It was a question that I had to find answers to, but for now, my focus is completely on the task at hand at Harris. The meat is prepared for pickling and cured in a new way. This week, for the first time ever, it was done in this way at the world-famous operation of C & T Harris. 

It is Sunday now, and the most momentous week of my life came to an end. I am both exhilarated and exhausted.  Despite the quality of the Danish bacon, it is, in my opinion, the British bacon of C & T Harris that we have to imitate and similar to how they improved on the Irish and Danish method, in the same way, we have to use their bacon as the starting point and seek to improve on it.

(Below, some Harris memorabilia by Steven Thomas‎.)

Oscar, I can report that I have found what we are looking for and that it will not be of little benefit if you could join me in the United Kingdom for a time. My interest is in chemistry and meat science, and you are far better at machines and understanding engineering drawings. I am doing my best to learn as much as I can, but I am convinced that if you spend the same time with the engineers, that the benefit to us will be greatly enhanced by your ability to grasp it better.

Children, I am seeing our plan coming together in a way that I could not have imagined. Please take the letter to my dad also and to Elmar and Juanita in Hermanus. I also sent a mail to Dawie Hyman and invited him to visit me in Calne.  He is an engineer and I am convinced he will not only find it immensely interesting but will be able to offer insights and help with our Cape improvements.

I am planning to return to Cape Town with Minette for a short break. She is needed at her job in the bank, and I will enjoy travelling back with her. Oscar, maybe you can visit us, and we can all return to the Cape together. Returning will also give me the opportunity to see you guys again, and I have to attend to important matters. Here in Calne, we stay in an Inn, and it will be great to have a bit of a break from this. It is different from Denmark, where we could stay with Andreas and his family. I will keep you all abreast of my plans.

Lots of greetings and love from Calne,

Your friend and dad,

Eben


Further Reading

Bacon Curing – a historical review

Tank Curing Came from Ireland

The Mother Brine

Occurrence of “mild cure” in English Newspapers

Mild Cured Bacon – Recreating a Legend


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(c) eben van tonder


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Notes

(1)  Callow gave us a description of Wiltshire cure in 1934.

(2)  Ingram, Hawthorne and Gatherum described this process in 1947 of how it was possible to manage the amount of nitrite in the brine by adjusting the salt (sodium chloride) concentration of the brine.

(3)  A 1958 publication gives this description of a typical Wiltshire pork cut (Warde, F. and Wilson, T.;  2013:  55).

(4)  The equipment drawings and photos are from William Douglas & Sons Limited, 1901, Douglas’s Encyclopaedia, University of Leeds. Library.  All or at least most of these equipment pieces would in all likelihood have been found in the Harris factory.

(5)  I estimate that the transfer of technology must have happened either right at the close of the 1800s or right at the beginning of the 1900s.  The person who brought the technology to England is not known by name, but casting myself in this role makes it realistic since the transfer, in all likelihood, involved a scenario similar to what I am describing. I have written extensively about it in Bacon Curing – a historical review.

(6) Ch Hansen sells the following starter packs for such applications using:

  • Scarnosus subsp. utilis
  • Scarnosus 
  • S. xylosus

(7) Plastic pallets are used today in the place of steel or stainless steel pallets. Wood is completely forbidden is modern factories.

(8) Tumbling is incorporated in the maturing step by modern producers. They then place the bacon for between 1 and 2 days in Wiltshire cover brine followed by 2 – 3 day maturing.

(9) Storage time of bacon is discussed here if it’s stored without proper packaging. For a detailed discussion on the subject, see The Freezing and Storage of Meat

(10) I asked the question at the start of my processing career at Woodys. I used the exact method described here.

(11) (add to next chapter) When I returned to Calne many years later, Michael was still working with them and we conducted an experiment where we added colour to the brine and used one of the smaller autoclaves to evaluate the rate of diffusion. We did not use the injector needle to inject brine as is done in step one. This way we could see the effect of the vacuum on its own. At the end of the 5-hour curing process, we cut the muscle in two and saw that brine entered the meat, but it was not well diffused through the muscle.

We repeated the experiment but this time we injected the meat first as per the prescribed method. When we cut that meat open at the end of the process, we saw that small brine pockets formed in the meat, but not even this distributed the brine evenly. It explains to me on the one hand why there are many problems with bacon cured in this way and on the second hand, it shows the superiority of the tank curing or mild bacon system where brine is allowed to enter the meat over several days. Tank curing, therefore, removes the expensive cylinder and vacuum and it achieves much better brine distribution using time. It can be shown that the distribution of brine through the meat happens through diffusion which is simply the movement of the brine from an area of high concentration to an area of low concentration.

The most important contributor of diffusing the brine through the meat quickly and evenly still remains hot smoking. We concluded our experiment by hot smoking and heating some of the bacon in a pale dry chamber after we injected the meat with colour. The results were exactly as we expected. Proper diffusion of the brine took place during smoking. My guess is that it takes place as the meat heats up. This concept of autoclaving the bacon would later be combined with the concept of tumbling or massaging the bacon to create vacuum tumblers.

(12) The Wiltshire system was by no way developed exclusively in the Harris factories and was without question not a single event. The fact that sal prunella had to be replaced with saltpetre is something that the curers in Wiltshire worked out somewhere between the end of the 1800s and the beginning of the 1900s. For a comprehensive treatment of the likely development and progression of mild curing to the Wiltshire system, I refer you to Mild-Cured Bacon and the Curers of Wiltshire.

References

Ingram, M.. 1951. Internal Bacteria Taints (‘Bone Taint” or ‘Souring’) of Cured Pork Legs.

Mrak, E. M., Stewart, G. F. (Editors). 1953. Advances in Food Research, Volume IV. Academic Press.

Lawrie, R. A., Ledward, D. A.. 1985. Lawrie’s Meat Science. Woodhead Publishing.

Sutherland, J. M., Sutherland, J. P.. 1995. Meat and Meat Products: Technology, Chemistry and Microbiology. Springer Science & Business Media.

Wrexham Advertiser (3 March 1894)

Wyman and sons. 1888. Wyman’s commercial encyclopedia of leading manufacturers of Great Britain.