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 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
The principal bacon produced by Harris at this point is no longer sweet cured bacon. Under John harris, a new progression was made from the sweet cure system to what they call pale dried bacon. 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 is 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.
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.
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. 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 machine’s featured above are later small-scale designs to achieve effectively the same thing. Harris who invented this processes, however, build 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 with 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 was 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 invension.
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 re-use 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. The old brine contained the nitrates which 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 only top quality saltpetre and the one distinguishing feature of re-using the old brine.
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 can not 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 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 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.
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 improving on it. By the end of the week, this has been achieved.
Let me begin by giving you a schematic representation of the system.
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.
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 that mostly afflicts pork is called PSSE which stands for pale, soft and exudative meat. The meat becomes soft, pale and mushy and it can not hold the brine. It is completely unsuited for curing. The other condition that can arise is dark, firm and dry meat (DFD) which normally afflicts 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 can not permeate the meat thoroughly resulting in uncured patches in the meat which is 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 set 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.
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)
– The Brine Makeup
Curing takes 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 (saltpeter) 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. In other words, inject the brine very gently!
– Dry Salting with liquid Brine Imersion
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 remained 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.
– The Reuse of Old Brine
A distinct feature of the system is that old brine are re-used. John Harris already understood this. The live brine system meant that nitrates have been reduced to nitrites already in the old brine where bacteria removes one oxygen atom from the saltpetre molecule. The makeup of the tank pickle is 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 therefore 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 re-use of old brine comes from the 1830 edition of The Complete Grazier. The report says that wet cure is more expensive then 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 be 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 from at least the 1820s. The earliest mention I could find about the re-use of old brine comes from the 1830 edition of The Complete Grazier It says that liquid brine may appear to be more expensive than if it is done “in the common way” which in the context should refer to dry curing or rubbing a mixture of dry ingredients onto the meat. The edition of the Complete Grazier referred to is from the 5th edition which means that by this time, the description may already be 5 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 of 1820 and 30 was a far cry from the complete system of William Oake from the same time in Ireland where the multiple (continues) 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.
– Auto Curing
I learned that reusing old brine was part and parcel of the auto curing system of bacon production which, by 1861was already in use in England, Sweden, Denmark, and Canada. The process is described as follows. The pig is slaughtered in the usual way and the sides trimmed and chilled. After chilling, it is laid out in rows on a sort of truck that exactly fits into a large cylinder of steel 32 feet long, 6 feet in diameter and which will hold altogether 210 sides. When the cylinder is filled, the lid, weighing 3 ½ tons (7000lb. Danish) is closed and hermetically sealed by means of hydraulic pumps at a pressure of 3 tons to the square inch.
A vacuum pump now pumps all the air out which creates a vacuum of 28 inches. It takes about an hour to pump all the air out. The brine channel which leads to the brine reservoir, holding around 6000 gallons of brine is now opened. The brine rush into the chamber and as soon as the bit of air that also entered has been extracted again, the curing starts. It happens as follows.
The brine enters the cylinder at a pressure of 120 lbs. per square inch. It now takes between 4 and 5 hours for the brine to enter the meat completely through the pores which have been opened under an immense vacuum. When it’s done, the brine runs back into the reservoir. It is filtered and strengthened and used again.
A feature of the system is that it allows the bacon to be shipped overseas immediately, assuming that maturation would happen en route as was usual. The time for the total process is around three days. On day 1 the pig can be killed, salted on day 2 and packed and shipped on day 3.
There are two brine reservoirs. The one is used with a stitch pump to inject brine into the sides as usual before they are placed in the cylinder and the second tank is used. The largest benefit of this system is the speed of curing and many people report that the keeping quality of the bacon and the taste is not the same as bacon cured in the traditional way.
There is a fascinating point to be made here. The system cured the meat in a short time, not because of the vacuum or the penetration of the brine into the muscle, but because it too used the power of the old brine which is based on the reduction of nitrate to nitrite. The vacuum had an impact in rather keeping the brine inside the meat and sealing the meat fibres over the areas where holes were created during injection and brine normally leached out again.
It clearly is a progression of the mild cured system. The brine is distributed into the meat through step one and not primarily by what they call the “opening of the meat pores.” The fact that a vacuum is created without question adds to the uptake of the brine in the meat, but far less than what was ascribed to it. (11)
– Maintaining Adequite Levels of Nitrites and “Cleaning” the Brine
Let us return again to the concept of the reuse of the brine. 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 which they got from the Irish.” 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 and 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 Jeppes 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 still remains somewhat of a question in my mind. 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 why hot smoking contributes materially to this process. The downside is that there is a greater risk for microbial spoilage when the meat is warm. The way to overcome this is through very strict procedures. One way to still make use of 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)
The sides are placed in a maturing cellar for 6 to 7 days. Maturing days for as low as 2 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 at 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 the 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 2 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.
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 mould formation of 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)
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 occurred, one can normally just wipe this off unless the flavours have been affected. Normally this does not happen unless yeast developed 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 is prone to spoilage. (Mrak,1953)
It is done! The Irish invention of mild curing was acquired by the Danes and now finally made its way to England and the operations of C & T Harris where they started to refer to it as tank curing. Tank curing is then the English modification of the mild curing system of William Oake. A question immediately came up as to why they did not get this from Ireland directly much sooner, especially in light of the fact that 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 have 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. Harris adopted the Danish system and tank curing was born!
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,
Bacon Curing – a historical review
Occurrence of “mild cure” in English Newspapers
Mild Cured Bacon – Recreating a Legend
(c) eben van tonder
“Bacon & the art of living” in bookform
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(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:
- S. carnosus subsp. utilis
- S. carnosus
- 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) 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.
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.