Bacon and the art of living 12: Ice cold for bacon

January 1892

Dear Oscar,

I am glad to hear that you had a good Christmas in Cape Town.  I am even more excited about the prospect to see you and our old friend, David Graaff next month.  I wish I could join the two of you on a long boat trip.  In Ava’s last letter she wrote how you read through all the letters I have written her and the kids last year.  This is good because it gives you a better sense of what has been happening here.  At least more information than the weekly telegram.

The project we have undertaken has turned out to be quite a venture.  I am excited to learn about the premises you are looking at in Kraaifontein (1).

In the Slaughter House by  Lovis Corinth.  1893
In the Slaughter House by Lovis Corinth. 1893

 

My friend, it is interesting how things work out.  The reason why we decided that I should be in Denmark is because we met a Danish spice trader in a pub in Johannesburg.  I am here purely at his recommendation and because he put us in touch with Andreas. (2)

Without knowing it, the Harris’s from C & T Harris (Calne) Ltd have probably created the modern methods of producing bacon.  (mfo. histories. harris)  Andreas knows the Harris family well.  He is one of the people who brought the Harris-technology and their Wiltshire cure to Denmark.

It is however Denmark which is fast developing into one of the centers of the bacon universe.  Denmark, like South Africa, is a rural country.  Farm boys, like back home.  Around the world they have been known for some time now for their dairy farming and their butter.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

When you make butter, skim and separated milk is a by product of butter making.  It also is an excellent food for pigs.  The Danish farmers realised this and developed an immense bacon industry.  In 1890 they exported 59 084 270 Lbs of bacon and ham (26 800 metric ton) (3) (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

One of the reasons for creating the bacon empire was that the import of live pigs from Denmark to England was stopped.  The ingenious Danish farmers responded to this by organising themselves into cooperatives and the cooperatives build bacon factories all over the country.   (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)  I have not been able to find out who was behind this initiative and would very much like to know more about it.  Men and woman of vision should be emulated and I am eager to know more about the people who initiated this.

This again resulted in a huge increase in the import of bacon into Great Britain.  It is projected that the bacon imports compared to the 1876 figure of 3 560 176 cwt will double by 1897. (4)  The main countries that supply England with cured bacon are the USA, Canada, Sweden and of course, Denmark.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

These figures can give us confidence that we are on the right track with our bacon curing venture.  David Graaff is coming to Denmark to source bacon, but I think we can convince him to rather buy the bacon from us and not only sell our bacon to passing ships and to customers on the Rand, but to export our South African bacon to Great Britain.  During your trip, this is a subject that will be a good discussion point.

The factory where I am working is one of these cooperative factories.  Jeppe is running it. (5)

Like us, the focus in Denmark is to reduce the course nature of the farm-cured bacon with a much milder cure. This has been the trend around the world and can only be done in a large bacon plant due to the equipment required to achieve this.  In particular, refrigeration. (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

Danish bacon rated as the best in the world.  From The Iola Register, Friday, 22 Nov 1895
Danish bacon rated as the best in the world. From The Iola Register, Friday, 22 Nov 1895

The factory’s in Denmark comprises of the following, which is also a list of what our Kraaifontein factory should look like.  There is the slaughter-house, the dressing room, chill room, cellar, engine and refrigerator rooms, boiler house, smoke house, baling loft and offices.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

Besides bacon, it is advisable to provide a “smalls” department for the making of sausages, canning and lard refining so that every part of the carcass is used.  Including the trim.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

The most important department is the machinery for refrigeration.

Cold helps to reduce the temperature from the carcass faster after slaughter, thus preventing the formation of Pale, Soft Exudative (PSE) meat which is a big problem for the pork industry since it affects the quality of the meat and makes it difficult, if not impossible to cure it.

Refrigeration enables us to store meat from animals we slaughter in the winter and cure it in the summer when the demand for meat is generally much higher than in winter.  It makes it possible to buy meat from Argentina or Australia, ship it to South Africa and cure the bacon in our state-of-the-art bacon plant.  These we will procure from Combrinck & Co.

It is refrigeration that allows us the use of a milder cure since much of the initial preserving function is accomplished through cold temperature which allows for the brine to permeate every part of the side of bacon before it spoils. (Daily Telegraph, 26 April 1910: Page 10:  Bacon curing)  The salt and saltpeter creates an internal barrier against bacteria while smoking create an external shield, thus taking over from refrigeration.

If we so desire, we can freeze the bacon and ship it to Great Britain where it can be sold without any fear that it will somehow purify if an inferior saltpeter has inadvertently been used.

Carbonic acid refrigeration machines has been most popular for bacon factories in Denmark.  Ammonia is generally not suited for this kind of work on account of the smell and the inherent danger’s in its use.  No smell is attached to carbonic acid and safety valves makes it quite safe to use.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing) (6)

The pickle pump is gaining wide popularity in bacon curing, but I will devote an entire discussion on this at a later stage.

Refrigeration changed the face and taste of bacon.  There are a few things to remember when dealing with refrigerated meat in bacon production.

Edward Smith cautioned against the fact that frozen meat is not in all respects equal to fresh meat.  He wrote in 1873, “… the effect of cold is to lessen, if not to change, somewhat the flavour of the substance, so that whilst it may be really good food it does not fully equal recent fresh meat.”  (Smith, Edward, 1873: 25)

I have been wondering if this is the case and what are the factors in using frozen meat and making freezing part of the curing plant that we must keep in mind.  There are quite a number facts related to refrigeration that has become so commonplace that I will not be looking at it here.  The optimal time meat can be stored in a frozen state for example.  (7) The effect of cold on different pathogens must be thoroughly looked at, but I want to write to you at length about the matter of controlling and eradicating meat spoiling bacteria.  Like the matter of pickling, I will do this at a later stage.

Advert for Danish Crown Bacon.  From Mansfield News Journal, Thursday, 1 March 1962
Advert for Danish Crown Bacon. From Mansfield News Journel, Thursday, 1 March 1962

The few aspects that I think will be “news worthy” are the following.

Slicing Temperature

People want to buy their bacon ready sliced.  When producing pre-sliced bacon with a high speed slicer, slicing temperature is of the greatest importance.  If the temperature of the bacon is too low, the blade of the slicer will be subject to excessive wear and the bacon will shatter.  If the temperature is too high, the soft bacon sticks to the blade and the fat is torn away from the lean.

There has been many experiments to try and determine the optimum slicing temperature.  Salt percentage has a huge influence on the freezing point of the bacon.  However, the exact salt percentage varies greatly in bacon, even bacon in the same batch.  The other variable is the particular slicer used.  Other factors that affect slicing temperature are maturing time, the water content and the blade speed.  These variables are so great that a general rule in terms of slicing temperature is impossible.  Slicing temperature must be determined experimentally on the ground and adjusted per batch.  (Evans, J,  2080:  137, 138)

The slicing manager must develop practical experience and be constantly aware of the temperature of the bacon and the resultant slice quality. He or she will get to know the different slicers and the different bacon cuts (back, belly, leg, neck, shoulder) and will have to adjust the temperature and blade speed in order to achieve the best slicing results.

Tempering

There is not an exact definition for what tempering is in the meat industry.  The term generally refers to either lowering or rising the temperature of meat to prepare it for the next processing stage.  It includes thawing meat for processing or setting the meat at an optimal slicing temperature. (James, S. J, et al;  2002:  149)

Single Stage Tempering for slicing

It is important to have the right stiffness in the meat when sliced with a high speed slicer (800 – 1400 slices per minute). This is achieved by presenting the bacon log to the slicer in a semi-frozen or frozen state.  If the temperature is not optimal, meat texture is damaged in slicing which leads to a loss in slicing yield. (James, S. J, et al;  2002:  149) Single stage tempering is when the bacon joints are put on a trolley, wheeled into a freezer that is set at slicing temperature and it remains there until the bacon has reached slicing temperature, evenly throughout the meat.

In experiments, pork loins were held in a room set at – 18 deg C.  After 18 hours the surface was at – 10 deg C, but the center was still well above – 7 deg C.  An average weight loss of 1.88% was observed over this time, increasing by another 1.88% if the meat was held for a total of 64 hours (which can happen over week-ends). (Evans, J,  2080:  139)

The biggest problem with the single stage tempering system is that the single tempering system has to fulfill conflicting roles.  It must remove temperature from the bacon and in order to achieve this, a reasonably large temperature difference is required between the bacon and the air as well as air movement.  Then, towards the end of the process when the heat has been removed, a small temperature differential and minimal air movement are required to attain an even temperature and to reduce the rate of weight loss.  (Evans, J,  2080:  139)

The other large drawback is of course that of space.  Large refrigeration rooms will be required to perform this step over a long time period.

Two Stage Tempering for slicing

In this system, the bacon is blast frozen and then placed in an equalising freezer.  The objective of blast freezing is to remove the required amount of heat. (Evans, J,  2080:  139)

Here, a large difference in temperature between the bacon and the air is achieved as well as air movement.  (Evans, J,  2080:  139)

An economical objective is to try and have both both stages completed under 8 hours.  Two factors that will extend this time are if, during the initial blast freezing, either to much or to little heat has been extracted. (Brown, T, et al,  2003:  690 – 697)

The longer the bacon has been in blast freezing, the lower the equalization temperature would be. (Brown, T, et al,  2003:  690 – 697)

Generally, the longer the total processing time, the more the weight loss will be.  In the end, the correct slicing temperature is probably more important than the small weight loss brought about by a longer processing time.  What is of the utmost importance to the quality of the bacon cuts are at the correct slicing temperature. (Brown, T, et al,  2003:  690 – 697)  If the total two stage processing time is extended beyond the 8 hour target in order to obtain the correct slicing temperature, this is better than not achieving the required temperature in the meat.

“Optimising a two-stage tempering system using a purely empirical technique would be a costly, labour intensive process. Reliable predictive techniques would substantially improve the process.”  (Brown, T, et al,  2003:  690 – 697) Such a process must be developed in each factory.

Freezing times and purge

Rate of freezing is one of many factors that impacts on the occurrence of purge or syneresis after packaging due to damage of freezing to the muscle structure. (8)  Purge is when, after the bacon has been packed and is thawed out to a temperature of between 0 and 5 deg C, there appears a liquid in the packaging.  The same is true for thawing which also damage the muscle structure and produce drip loss.   (James, S. J, et al;  2002:  278)

Freezing, in general, always reduce the water holding capacity of the meat and therefore increases drip loss.  (James, S. J, et al;  2002:  37)

Slow freezing produce large extracellular columns of ice of greater continuity than the small intracellular ice crystals formed during fast freezing   (James, S. J, et al;  2002:  278)

At slow freezing the extracellular water freezes first.  As freezing continues, the ice crystals grow.  This can result in salt crystallization and even pH changes.

Repeated freeze-thaw increases drip loss.  (James, S. J, et al;  2002:  39)

Fresh and previously frozen meat taste the same

As far as Edward Smiths assertion that fresh meat is better in some respects than previously frozen meat, this is true on a technical level as far as water holding capacity, pH and such matters are concerned, but not as far as tenderness, flavour and colour are concerned.

Numerous blind tests have been done that show that consumers are unable to tell the difference between fresh meat and meat that has previously been frozen.  (Kennedy C. J.  2000:  89)  Edward Smith in this appraisal of frozen meat in 1873 have either been talking about meat that was subject to some form of abuse (such as temperature abuse) or he was displaying an common aversion against previously frozen meat that is still present today.  Studies have shown that consumers are willing to pay double for chilled meat vs frozen meat.  (Kennedy C. J.  2000:  89)

Freezing will be one of our biggest challenges in our new factory and much time will have to be spend on designing an optimal system.

My guess is that you and David Graaff will have much to discuss on your voyage from Cape Town to London on one of Curries steam ships and on your onward journey to Copenhagen.

I also know that you and David both enjoy hiking and I am planning a hiking excursion across one of the islands in Denmark.

I am excited about your visit and have been looking forward to it for many months.

Please send my regards to Willem, James, Anton and your mom and dad.

Greetings,

Eben

Bacon and the art of living Home Page

Notes:

(1)  Woody’s Consumer Brands (Pty) Ltd started construction at 7 Assegaai Road, Kraaifontein in October 2012.  They converted two large carcass chillers in a 30 year old factory into a bacon factory.  Kraaifontein to the North of Cape Town, just outside Paarl.

(2)  A Danish spice trader did in fact suggest to Oscar and Eben that they visit Denmark to gain experience in bacon processing.  He introduced them to Andreas.  This meeting took place in the winter of 2011.

(3)  Bacon and ham Export figures from Denmark

1890:  59 084 270 Lbs  (26800 metric ton)
1894:  92 348 457 Lbs (41 888 metric ton)
1895: 121 790 311 Lbs (55 243 metric ton)

(Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

(4)  The import of cured bacon in Great Britain doubled from 1876 of 3 560 176 cwt to 7 315 613 cwt in 1897.  The value of the 1897 cured bacon imports were 8 867 846 sterling.  (Daily Telegraph, 2 February 1901: Page 6:  Bacon curing)

(5)  Jeppe has been responsible for bacon at the Danish company, Tulip for many years, based in the United Kingdom.  Tulip is owned by Danish Crown.  The first Danish cooperative slaughterhouse was set up in Horsens in 1887. This slaughterhouse is now part of Danish Crown.  (Danishcrown.com. FAQ. Facts)  The cooperative model is still applied to this day in Denmark.  The large bacon factories are owned by the farmers.

(6)  Ammonia refrigeration plants are today one of the most popular, cost effective and safest form of industrial refrigeration.

(7)  The impact we are discussing here is of course matters that have all been considered post 1920’s, but for the sake of relevance, I include it here.

(8)  Other factors impacting on the occurrence of purge are the breed of the animal, diet, physiological history, slicing temperature and equipment factors such as the sharpness of the slicing blade.

 

References

Brown, T, et al.  2003.  Practical investigations of two-stage bacon tempering.  International Journal of Refrigeration 26 690–697.

Daily Telegraph, Launceston, Saturday 2 February 1901.  Article:  Bacon curing.

Daily Telegraph, Launceston, Tuesday 26 April 1910.  Article:  Bacon curing.

Evans, J.  2080.  Frozen Food Science and Technology.  Blackwell publishing.

* James, S. J, and  James, C. B.  2002.  Meat Refrigeration.  Woodhead Publishing Limited.

Kennedy C. J.  2000. Managing Frozen Foods.  Woodhead Publishing Limited.

Smith, Edward. 1873. Foods. Henry S King and Co.

http://mfo.me.uk/histories/harris.php

http://www.danishcrown.com/Danish-Crown/FAQ/Facts.aspx

 

Pictures

Figure 1:  http://hoocher.com/Lovis_Corinth/Lovis_Corinth.htm

Figure 2:  The Iola Register, Friday, 22 Nov 1895

Figure 3:  Mansfield News Journal, Thursday, 1 March 1962

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