Factors Affecting Colour Development and Binding in a Restructuring System Based on Transglutaminase

Factors Affecting Colour Development and Binding in a Restructuring System Based on Transglutaminase.
By: Eben van Tonder
1 June 2018

The articles on the complete bacon production system are available in booklet form:    https://tgrestructuringofmeat.pressbooks.com

INTRODUCTION

I started experimenting with Ajinomoto’s Activa almost 5 years ago.  In preparation for that, I wrote an article, Restructuring of whole muscle meat with Microbial Transglutaminase – a holistic and collaborative approach, which I updated over the years.

I have been approached by countless people from around the world with questions and insights which I did not address in my initial article.  I continued to gather bits of information, stored in mails to myself, learn from production managers I got to know in every part of the world and great articles I discovered over the years as I worked on a daily basis to do first-hand experiments at Woody’s and I tried to answer these questions for myself and for others while, always, working on improving the system.

It is time for a completely new follow up article where I address these issues systematically.  I look at heat treatment, colour development, moisture loss, protein denaturing, phosphates, salt, deboning, meat quality, pressure, freezing, chilling and gelation in relation to the use of TG.  I continued to look at what an optimal TG blend will look like and the aspects that our production systems must incorporate.  I also examine possible future developments in thermal processing and a few alternative ways to set up a production line where TG is incorporated into a grid system for the restructuring of large meat muscles, mainly for the production of bacon.

The number one question I was asked over the years is if TG affects meat colour.  Some researchers reported slight colour changes on fresh meat, but as far as processed meats are concerned, it is an irrelevant question since there are much more important factors affecting colour than the small impact that TG may or may not have.  Lets very briefly look at heating, colour development, and moisture loss to illustrate my point.

We begin with a review of the curing process and the effect of heat and smoke on colour development and moisture loss before we turn our full attention to a discussion of other factors affecting TG.

PROPER COLOUR DEVELOPMENT BEGINS WITH CURING:  THE IMPORTANCE OF RESTING, AFTER INJECTION, BEFORE SMOKING

CodeCogsEqn (11) to CodeCogsEqn(8) to NO 

When sodium nitrite is placed in solution in the brine preparation phase, the crystal structure breaks up and the ions separate into Na and CodeCogsEqn (4).  Nitrous acid is formed.    This hydration of nitrous acid is an important time-consuming reaction (Krause, B. L.; 2009: 9).

After the formation of nitrous acid (CodeCogsEqn (11)), the next step “is the generation of either a nitrosating species or the neutral radical, nitric oxide (NO).”  (Sebranek, J., and Fox, J. B. Jn.; 1985:  1170)  A nitrosating species is a molecular entity that is responsible for the process of converting organic compounds into a nitroso (NO) derivatives, i.e. compounds containing the R-NO functionality.  During resting, the most important one is the formation of Nitrosyl Chloride (NOCl). This is one of the good reasons why leaving out salt from bacon curing is not advisable.  The time-consuming nature of these reactions is also the reason why a resting phase is vital.

In a large commercial high-throughput bacon curing plant we found that an optimal processing sequence has the following sequence.  A few variations of this basic model will be proposed in this article, but this is the model that I used with great effect for many years and other models, if they survive critical theoretical scrutiny, needs to be tested.

  • injecting the meat,
  • tumbling it,
  • resting it for between 12 and 24 hours (depending on the curing room temperature),
  • tumbling it again to pick up brine that leached out during the maturing or colour development stage and,  This time, add TG blend.
  • grid filling
  • smoking/Thermal Treatment
  • de-gritting
  • blast freezing
  • equalizing
  • slicing and packing

Lets now focus on colour development during smoking and thermal treatment to understand optimal smoker chamber temperatures.

PROPER COLOUR DEVELOPMENT:  THE IMPORTANCE OF SMOKING

Cold smoking is normally seen as smoking where the core temperature will remain below 35 deg C.  We use hot smoking where the core temperature riches > 35 deg C but < 45 deg C.  Smoking and thermal treatment are therefore considered jointly.  Temperature effects product taste, meat toughness, binding, coulour, and moisture loss.

Reddening

During reddening, the temperature is increased, extraction flaps in the smokehouse closed to maintain humidity, and sulfhydryl groups are released which is a reducing substance in meat and important in proper cured colour formation.  Fraczak and Padjdowski (1955) indicated that 80°C is the critical temperature for the decomposition of sulfhydryl groups in meat.” (Cole, 1961)  (Reaction sequence)

Smoking

During heating and smoking, there are several changes in the meat that has a direct effect on the colour development.  The nitrosating species that is more dominant than NOCl is smoke due to the presence of phenolic compounds.  In addition to the heat release of sulfhydryl groups, the pH is reduced in the meat.  Randall and Bratzler (1970) noticed an increase in the myofibrillar protein nitrogen fraction, pH and free sulfhydryl groups of pork samples that were only heated, and a decrease of these values in the samples that were subjected to heat and smoke. “Results of this study indicated that smoke constituents react with the functional groups of meat proteins.” (Randall, 1970)  These results seem to support a reddening step before smoke is applied due to the fact that heating would release the sulfhydryl groups and during the smoke steps, the pH will be reduced.  (Reaction sequence)

DENATURING VS COAGULATION

With our consideration of smoking on meat, we have also entered the discussion of the effect of heat on meat.  Before considering the effect of heat on the protein lets first see how the heat gets to it.

Mechanism of heat transfer

Heat is transferred during cooking through conduction, convection, and radiation.  “Spakovszky and Greitzer (2002) defined conduction as ‘transfer of heat occurring through intervening matter without bulk motion of the matter,’ convection as heat transfer due to a flowing fluid, either a gas or a liquid, and radiation as ‘transmission of energy through space without the necessary presence of matter.’   Radiation can also be important in situations in which an intervening medium is present, such as heat transfer from a fire or from a glowing piece of metal (Spakovszky and Greitzer 2002).”  (Yu, T.Y., et al, 2017)

“Meat cooking usually involves more than 1 mode of heat transfer (Bejerholm and others 2014).”   During cooking in a smokehouse, heat treatment is achieved through dry heat surrounding the meat, but during reddening and smoking the air is or become moist and moist-heat (hydrothermal) thermal processing uses hot steam. Smoke House thermal treatment, including smoking, is, in reality, a combination of dry heat and moist heat.  (Yu, T.Y., et al, 2017)

“Conventional cooking of meat results in heterogeneous heat treatment of the product on account of steep temperature gradients (Tornberg 2013). Emerging mild cooking techniques such as ohmic cooking can achieve a more homogeneous heating by heating the entire volume of meat at the same time (Tornberg 2013).”  (Yu, T.Y., et al, 2017)  THis is an important point for consideration in a continuous, fully automated system.

This is important in considering the effect of heat on the grid system with holes.   The present role to steel ratio is 1:1,8.  The exposed meat area is therefore approximately half (take the edging to be approximately 0.02 to give the total ratio of 1:2).  This amplifies the effect of heating, but by what factor? This needs to be determined experimentally between different smokehouses.  I have determined a variety of different options in smokehouse settings over the years.

“Heat may cause proteins to lose their native conformation (denature) by providing the polypeptides with kinetic energy, increasing their “thermal motion,” and thus rupturing the weak intramolecular forces (such as nonpolar interaction, various kinds of electrostatic interaction, and disulfide bonds) that hold the proteins together (Davis and Williams 1998). As the temperature increases, a protein starts to unfold. When almost all the tertiary and secondary structures are lost, the unfolded protein may aggregate, have its disulfide bonds scrambled, undergo side-chain modifications (Davis and Williams 1998), and cross-link with other polypeptides. Aggregation is the consequence of nonpolar interaction between heat-denatured proteins whose hydrophobic groups have turned outward into the surrounding water, in order to adopt a lower energy state (Davis and Williams 1998). A variety of side-chain modifications, such as those induced by oxidation or the Maillard reaction, have been characterized in proteins following heat treatment.”  As heat increases, the 3-dimensional structure of meat proteins change.  These changes manifest in a change in colour and gelation.  (Yu, T.Y., et al, 2017)

DEVELOPMENT OF NITROSYLMYOCHROMOGEN

“Upon thermal processing, globin denatures and detaches itself from the iron atom, and surrounds the hem moiety.  Nitrosylmyochromogen or nitrosylprotoheme is the pigment formed upon cooking and it confers the characteristic pink colour to cooked cured meats.”  (Pegg, R. B. and Shahidi, F; 2000: 42)

We also need to review the main muscle proteins found in the body.

SKELETAL MUSCLES

Skeletal muscles are bundles of muscle cells (also known as muscle fibers) embedded in connective tissue.  (Yu, T.Y., et al, 2017) These muscle proteins “are grouped into three general classifications: (1) myofibrillar, (2) stromal, and (3) sarcoplasmic. Each class of proteins differs as to the functional properties it contributes.”  (www.meatscience.org)

->  Myofibrillar Proteins

The first very important protein to take note off is the myofibrillar protein for the purpose of water binding and binding meat pieces together.  These muscle fibers are muscle cells, grouped into muscle bundles.  The structural backbone of the myofibrils is actin and myosin.  (Toldra, 2002) They are the most abundant proteins in muscle and are directly involved in the ability of muscle to contract and to relax.  (www.meatscience.org)  Myofibrils also include tropomyosin and troponin, regulatory proteins associated with muscle contraction.  Parallel to the long axis of the myofibril, are two very large proteins called titin and nebulin.  (Toldra, 2002)

Myosin is a protein which is described as the motor, and the structural protein, actin’s filaments are the tracks along which myosin moves, and ATP is the fuel that powers movement.  (Lodish, 2000)  Myosin “converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.”  (Cooper.  2000)

“Together, actin and myosin make up about 55-60% of the total muscle protein of vertebrate skeletal muscle, with the thicker myosin myofilaments yielding about twice as much protein as the thinner actin myofilaments. Actin alone does not have binding properties, but in the presence of myosin, acto-myosin is formed, which enhances the binding effect of myosin.” (Patterson, The Salt Cured Pig)  In meat processing, it is important to note that it is the myofibrillar proteins which are soluble in high ionic strength buffers.  (Toldra, 2002)

“Texture, moisture retention, and tenderness of processed muscle foods are influenced by the functionality of myofibrillar protein.”  (Xiong, Y. L.;1994)  The pork muscle that contains the most myosin is the longissimus dorsi or the eye-muscle or longissimus muscle on the loin.  “The muscle fiber bundles of the longissimus dorsi are arranged at an acute angle to the vertebral column.  The cross-sectional area of the longissimus dorsi increases towards the posterior part of the ribcage, but it has an approximately constant cross-sectional area through the loin.”  (Animal Biosciences)

-> Sarcoplasmic Proteins

“The sarcoplasmic proteins include hemoglobin and myoglobin pigments and a wide variety of enzymes.  Pigments from hemoglobin and myoglobin help to contribute the red colour to muscle.” (www.meatscience.org)  These proteins are water soluble.  Besides myoglobin and hemoglobin, this class of proteins also includes metabolic enzymes (mitochondrial, lysosomal, microsomal, nucleus or free in the cytosol).  (Toldra, 2002)

Very important to remember for the purpose of meat processing is that myoglobin is the protein pigment responsible for the red colour in meat.  The redness of meat is largely dependant on the concentration of myoglobin.  Myoglobin is the storehouse for oxygen in the muscle.  Because different muscles need different oxygen levels, the concentration of myoglobin will differ between muscles.  The loin muscles in pigs are for example used for support and posture and therefore contains low levels of myoglobin.  Myoglobin levels are further influenced by species, breed, sex, age (older animals generally have more myoglobin), training or exercise (this is why free-range pigs have more myoglobin than stall-fed animals), and nutrition. (Pegg and Shahidi, 2000)

-> Stromal Proteins

“Connective tissue is composed of a watery substance into which is dispersed, a matrix of stromal- protein fibrils; these stromal proteins are collagen, elastin, and reticulin.

Collagen is the single most abundant protein found in the intact body of mammalian species, being present in horns, hooves, bone, skin, tendons, ligaments, fascia, cartilage and muscle. Collagen is a unique and specialised protein which serves a variety of functions. The primary functions of collagen are to provide strength and support and to help form an impervious membrane (as in skin). In meat, collagen is a major factor influencing the tenderness of the muscle after cooking.  Collagen is not broken down easily by cooking except with moist—heat cookery methods. Collagen is white, thin and transparent. Microscopically, it appears in a coiled formation which softens and contracts to a short, thick mass when it is heated and helping give cooked meat a plump appearance. Collagen itself is tough; however, heating (to the appropriate temperature) converts collagen to gelatin which is tender.  In the consideration of a TG mix, collagen is one of our most important considerations.

Elastin (often yellow in colour) is found in the walls of the circulatory system as well as in connective tissues throughout the animal body and provide elasticity to those tissues.  Reticulin is present in much smaller amounts than either collagen or elastin. It is speculated that reticulin may be a precursor to either collagen and/or elastin as it is more prevalent in younger animals.”  (www.meatscience.org)

It is interesting that collagen has been used for centuries to create strings to bind things and for strings on musical instruments.  Catstring or catgut is made by twisting together strands of purified collagen taken from the serosal or submucosal layer of the small intestine of healthy ruminants (cattle, sheep, goats) or from beef tendon and has been in use for a long time 900’s AD.  (Wray, 2006)  Gut strings were being used as medical sutures as early as the 3rd century AD as Galen, a prominent Greek physician from the Roman Empire, is known to have used them.   (Nutton, 2012)

Abū al-Qāsim Khalaf ibn al-‘Abbās al-Zahrāwī al-Ansari (Hamarneh, et al., 1963)(Arabic: أبو القاسم خلف بن العباس الزهراوي‎;‎ 936–1013), popularly known as Al-Zahrawi (الزهراوي), Latinised as Abulcasis (from Arabic Abū al-Qāsim), was an Arab Muslim physician, surgeon and chemist who lived in Al-Andalus in the early 900’s CE. He is considered as the greatest surgeon of the Middle Ages (Meri, 2005), and has been described as the father of surgery.  (Krebs, 2004).  He became the first person to have used Catgut to stitch up a wound. He discovered the natural dissolvability of the Catgut when his monkey ate the strings of his musical instrument called an Oud. (Rooney, 2009)

Later, in 1818, the modern founder of surgery, Joseph Lister, and his former student William Macewen independently and quite remarkably, almost at the exact same time, reported on the advantages of a biodegradable stitch using “catgut”, prepared from the small intestine of a sheep.  Over the ensuing years, countless innovations have extended the reach of collagen in the engineering and repair of soft tissue in medicine and numerous other industrial applications. (Chattopadhyay, 2014)  The interesting point should not escape our notice that collagen is included in our TG mixes ta facilitate meat protein – TG – connective tissue – TG – meat protein binding structure.  Collagen is surface-active and is capable of penetrating a lipid-free interface.  (Chattopadhyay, 2014)

The other major constituent of meat is, of course, lipids or fat but I deal with this separately below.

During thermal processing, moisture loss will take place.  Let us predict the optimal temperature range that will give us the right moisture loss and colour development in the shortest possible time.  Countries such as Australia sell their bacon cooked but in the UK, New Zealand, Canada, the USA and South Africa, bacon is sold par-cooked.  I, therefore, consider temperatures which will be considered par-cooked and fully cooked.

DIFFERENCES IN MOISTURE LOSS

“Bendall and Restall (1983) systematically studied the physical changes occurring during heating of intact beef-derived single muscle cells, and also the very small myofiber bundles of 0.19 mm in diameter (containing 40 to 50 cells) at final temperatures between 40 and 90 °C. In addition, the authors also studied heating of larger bundles of 2 mm in diameter.”  (Yu, T.Y., et al, 2017)

According to their work, the stewing process progresses as follows:

From 40 to 52.5 °C

Denaturation of sarcoplasmic (include hemoglobin and myoglobin) and myofibrillar proteins occurs.  Related to colour development the denaturation will effect sarcoplasmic protein even though its denaturation probably occurs from at least 25 °C.   Related to moisture and the range of 40 to 52.5 °C, a slow loss of fluid from the myofibers into the extra-myofiber spaces occurs without shortening. (Yu, T.Y., et al, 2017)  The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity. (Ceresinoa, 2018)

Between 52.5 and 60 °C

At this temperature, there is “an increasingly rapid loss of fluid from the myofibers, reaching a maximum rate and extent at about 59 °C.”  There is no overall shortening at this temperature mainly due to heat shrinkage of the basement membrane collagen (type IV and perhaps type V as well) at about 58 °C.   (Yu, T.Y., et al, 2017)

Between 64 to 94 °C

Considerable overall shortening and a decrease in cross-sectional area are noted, accompanied by increased cooking loss with heat shrinkage of the endomysial, perimysial, and epimysial collagen.”  (Yu, T.Y., et al, 2017)

Long Stewing

“Long periods of stewing causes partial or complete gelatinization of the epimysial collagen, followed by the peri- and endomysial collagen, resulting in the soft and tender feature of stews (Bendall and Restall 1983). It is worth mentioning that meat with a high pH (Zhang and others 2005) or fat content (Wood and others 1986; Jung and others 2016) has been shown to exhibit higher water-holding capacity.”  (Yu, T.Y., et al, 2017)

The important aspect for us is the key temperature of < 52.5 where moisture loss becomes “rapid”.  This gives us an important upper “meat temperature” limit above which rapid moisture loss occurs.

The following section confirms the conclusion of par-cooked bacon’s optimal thermal processing range of between 40 and 52 deg C.  Due to inconsistencies in the smoke chamber, it is suggested that a maximum internal core temperature of 40 deg C is set.

KINETICS OF THERMAL DENATURATION

Kajitani, et al, (2011) studied the kinetics of thermal denaturation of protein in cured pork meat related to each of the three protein classes of meat proteins namely myosin (from myofibrillar proteins), sarcoplasmic proteins and collagen (from stromal proteins).  Of great interest to us is the sarcoplasmic proteins which include the pigment containing myoglobin.

The first important consideration is that the “thermal denaturation of muscle proteins such as myosin, sarcoplasmic proteins and collagen, and actin, occurs at different temperatures. To describe those reactions during thermal processing, temperature dependency of the reaction rate constant is necessary.”  As the level of NaCl in the meat increased, “the thermal-denaturation rate constant of each protein increased.” (Kajitani, et al, 2011)

Adding salt to the sarcoplasmic proteins means that it starts to denature at a temperature of around 50 deg C, reaching a peak at around 68 deg C.  Adding Sodium Chloride moves the graph to the left.

heat.png

Graph source:  (Kajitani, et al, 2011)

Having now considered thermal treatment and smoke in some detail, we can move to a consideration of TG in particular, but we will broadly keep looking at colour development, binding strength, and water loss.

TG is mixed into solution before added to the meat.  The TG mix contains connective proteins and the first important matter to take into account is the solubility of these proteins.

The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity.  Optimal pH for commercial TG was found to be between pH 5.5 and 6.0. (Ceresinoa, 2018)

DIFFERENCES IN SOLUBILITY

In terms of the use of Transglutaminase, different proteins are used in the TG mix as added connective protein to enhance the overall binding action.  When TG is mixed in a solvent before application, different solvents will provide different solubility which may concern operators.

For example, TG containing stromal proteins such as collagen which shows low solubility in a neutral aqueous solvent such as water but high solubility in a curing brine solution with phosphates and salts on account of the high ionic charge of this solution.

Skeletal proteins.png

From Yu, T.Y., et al, 2017.

The solubility of different proteins under various ionic strengths further informs us of the importance of salt and phosphates in solubilizing myofibril protein.  Mixing the TG into a small brine solution has in my experience the best results.

MIXING AND TUMBLING – COLOUR LOSS AND BINDING

The system I developed over the years and used with great effect is to mix a batch of “stuffing meat” which I use in conjunction with whole muscles.  Whether such a mix is made or comminuted muscle meat prepared for sausages, researchers have found that mixing time has an effect on the color and will increase the deterioration of the desired color if conducted in excess of 12 min” (Sun, 2009).  Over the years I noticed a similar colour change if whole meat muscles have been over-tumbles, but if the meat is smoked, the colour change is immaterial.

The greatest benefit of the system relates to binding.  The reason why I use “stuffing meat” is that this combines modern binding systems such as transglutaminase with old-school meat processing techniques, such as chunking, flaking and tearing.  Bhaskar Reddy, et al. describes chunking and its benefits as “passing the meat through a coarse grinder plate leading to decrease in the particle size not greater than one and a half inch cubes.  This technique increases the surface for the extraction of myosin and aids in better binding during mixing.” (Bhaskar Reddy, et al.; 2015)  This describes the system I currently use to produce the stuffing meat.  Bhaskar and his colleagues refer to flaking and say that “high-speed dicing or slicing machine is being used for flaking and reforming of restructured meat products. Fine flakes produce more acceptable appearance, increase tenderness and decrease shear force value”, referencing Mandal et al., 2011Reddy et al., 2015.  They add another category which they refer to as  “sectioned and formed meats” which are “primarily composed of intact muscle or section of muscle that are bound together to form a single piece”, quoting Pearson and Gillet, 1996Mandal et al., 2011Sharma et al., 2013.  This is the process then of taking the whole muscle meat and joining them together in the grid system.  My method combines then chunking with sectioned and formed meats.

The “old school” method relies on the combined effects of salt, phosphate and mechanical action.  Bhaskar Reddy, et al. (2015) references Boles and Shand, 1998 who found that “by using this technology, the product must be sold either precooked or frozen because the product binding is not very high in the raw state but high yields (25% above meat weight) are possible.

One of the benefits of the “old school” methods is the effect of meat particle size. “An increase in meat surface area and an increase in the availability of myofibrillar proteins for binding is the net consequence of comminution.” (Sun, 2009).

“In a study to evaluate mixing time on the binding effect of restructured meat, Booren, Mandigo, Olson, and Jones (1982) found that there was a significant linear increase in binding strengths up to 12 min of mixing at 28C.”  (Sun, 2009)

The excellent review article of Sun (2009) makes reference to a study by Ghavimi,
Rogers, Althen, and Ammerman (1986) where they assessed vacuum, non-vacuum, and nitrogen back flush processing conditions at 1–38C during tumbling of restructured cured beef.  Fascinatingly, they concluded that meat had higher cooked yields in a non-vacuum atmosphere. This, in the context of the application of Transglutaminase, is a very interesting observation.

I have long proposed a re-examination of the viability of vacuum tumbling, but I recognise the entrenched nature of this technology in modern meat processing plants and propose a new line set-up for investigation.

Injector -> vacuum tumbler -> 24 hours resting station -> add TG -> ribbon/ paddle mixer -> filling station -> smoking/ cooking -> de-gritting -> freezing – slicing -> packing.

This eliminates the re-routing of meat back to the tumblers which are expensive assets while it achieves the application of the TG, final pick-up of any brine that purged out of the meat during resting as well as the balancing brine added after injection.  In order to facilitate a proper pick up of this “loose brine”, some processors choose to add between 1 and 2% pork protein at this stage which will mean that the brine added during this step consists of the pork protein and the TG blend in a small amount of brine.

Lets first look at why a tumbler works.  The interaction of the meat, rubbing against the meat and the pressure created as the mass of meat falls to the bottom of the tumbler during the drum rotation causes pressure which then “activates” the protein by causing the highly swollen muscular protein cells to burst.  Bhaskar Reddy, et al., (2015) quotes Feiner, 2006 who stated that it is the “kinetic energy released during falling of meat pieces at bottom of the tumbler which serves to disrupt cellular membranes, which in turn causes protein extraction.  It is the baffles inside the tumbler which “move the injected pieces of meat up the wall of the tumbler and once the pieces of meat reach a certain height, gravity causes them to fall.”  (Bhaskar Reddy, et al., 2015)

This is, in my opinion far more aggressively and successfully achieved through a paddle mixer or a ribbon mixer than only the falling of the meat inside the tumbler.  Mixing in a paddle or ribbon mixer will, in my estimation, better develop the myosin protein to become “sticky.”  Remember that the aim of this step is to “solubilize the protein, creating a layer of activated protein on the surface of meat which is responsible for slice coherency in the cooked product.  The sarcolemma surrounding the tightly swollen muscle cells is, in my opinion, more likely to be destroyed by the impact of energy from paddles than only tumbling and myofibrillar proteins will be released and solubilized (which is the object of tumbling).  There is considerable academic and anecdotal support for this.  Dikeman and Devine state in their Encyclopedia of Meat science, second edition (2014), commenting on the fact that paddle mixers run at reduced revolutions per minute (rpm), that they “can be useful for applying mecahnical action to whole muscle pieces. . .  to produce a surface protein exudate without damaging muscle integrity.”  (Dikeman and Devine, 2014:  126, 127)

Meat must be mixed until they become tacky – almost furry.   “Rust and Olson (1973) found that the extraction of myofibrillar proteins on the surface of meat has two functions. One is to act as a bonding agent holding the meat surfaces together and the other is to act as a sealer when thermally processed and therefore, aid in the retention of water in the muscle tissue.”  “In addition, cellular disruption of the meat tissue occurs during tumbling which together with the curing additives allows the meat to improve the yield (Chow et al., 1986). Constraining connective tissue sheaths around muscle fibres are disrupted, allowing further myofibrillar swelling introduced by salt (Katsaras and Budras, 1993).  (Bhaskar Reddy, et al., 2015)

It is, of course, possible to mix the TG mix into the stuffing meat by hand, but one loses all the benefits listed above.  For the exact reason, I believe a more aggressive treatment of the whole muscle meat just prior to filling into the grids should yield far better reshaping and binding results.  Too little mixing will result in meat being “loose” and a failure to bind together.  Too much mixing, on the other hand, will result in a loss of tenderness and the product being “rubbery”.  (Pearson and Gillett, 1999)

The reason why mixing is essentially done in a tumbler under vacuum is mainly that, removing the oxygen, prevents oxidation.  This prevention of oxidation will, however, also be accomplished by maintaining a low temperature during mixing which is obviously also very good to control negative mirco-growth.  (Pearson and Gillett, 1999)

Bhaskar Reddy and colleagues state that tumbling or massaging (physical action upon the meat, in whatever form) “improves the speed of curing by increasing salt absorption.”  (Bhaskar Reddy, et al., 2015)  It is this reason why I still prefer the two-step tumbling.  The solubilization of the proteins by the fat and the phosphates are greatly enhanced if the meat is left to rest for 12 or 24 hours and re-tumbled/ mixed which of course will increase the protein bind.

Having made this statement, we get to a long-standing debate related to tumbling namely if one must tumble continually (uninterrupted) or if one must have intervals of rest periods.  For every study that intermitted tumbling is superior, there seems to be a study that shows continues tumbling is superior.  Why is the one preferred over the other?  Exactly because brine needs time to diffuse into the muscle.  (Krause et al., 1978)  One needs the drum to stop turning so that the meat can be immersed in the brine in order to absorb into it.  This is not achieved, as many believe, by the vacuum which presumably opens up the meat fibers and somehow pulls the brine into the meat.  The reason why this is done intermittently (tumble, rest, tumble, rest) and not in a two-step process of tumbling, unloading, resting in the chiller, loading into the tumbler and tumbled again, is presumably to eliminate the need to load and unload the tumbler twice.  In a high throughput factory, this should, in any event, be done with loading equipment and should not be a consideration.  I also doubt if the total time of resting in a tumbling program will be sufficient for the brine to be absorbed if one takes absorption rates into meat into account.

Whichever way I look at it, a two tumbling system is preferred over injection, resting, tumble, adding TG 15 minutes before the end of the program and grid filling (only one tumbling step).  There are simply too many advantages which are ignored which one will get in a system of injection, tumbling, resting, TG tumble, grid filling.

My only concern of using paddle mixers for the second step and not tumblers relates to the formation of foam.  If foam is created, this may lead to protein denaturation and the binding strength will be compromised (Kerry et al., 2002)  This will have to be evaluated.  In my own experience, when using a blender to do the stuffing meat, this has never in 2 years of using the technique created foam.  Whole muscles will have to be tested for foam formation which I know happens in a tumbler if only a partial vacuum is pulled.  I suspect the paddle mixer will work very well.

DIFFERENT GELLING ABILITY OF DIFFERENT PORK MUSCLES

A matter of interest is the different gelling strengths of different proteins.  Between poultry, beef, fish, milk, and pork, but also between different pork muscle groups.  This is of interest to me for choosing the best muscle to produce the stuffing meat.  Robe and Xiong (1993) reports that pork longissimus dorsi muscles (predominantly white) formed stronger gels when compared to pork serratus ventralis muscles (predominantly red).

One would not use the longissimus dorsi muscles to produce stuffing meat, but there may be muscle groups in the leg with similar visual characteristics.  Is there an advantage in using some of these muscle groups for the stuffing meat?  It is an interesting question that must be investigated.  Robe and Xiong (1993) concluded that their work indicates that “red and white muscle types (in pork) should undergo different processing treatments for optimum quality meat products.”

PRESSURE – COLOUR AND BINDING

Contrary to popular belief, pressing of the meat does not facilitate the binding or the effect of TG in any way.  (Pearson, and Gillett, 1999)  Pressing into moulds have a few important functions.  In the first place, it ensures the meat, particularly large meat pieces, are forced into a regular shape which is the key behind improved slicing yields.

The second reason for pressing relates to surface area and meat contact.  If there are cavities in the meat log, binding at those locations will obviously be compromised and the appearance of the meat slices, especially when bacon is sliced, will be undesirable.

SALT – COLOUR AND BINDING

Sun (2009) points out that “discoloration of restructured steaks can be caused by salt. A decrease in color desirability with increased salt levels has been observed by some researchers (Huffman & Cordray, 1979; Schwartz & Mandigo, 1976). The raw color could be improved by sodium tripolyphosphate (STP), which helps to compensate for the effect of salt (Schwartz & Mandigo, 1976).  As a matter of interest, Huffman, Ly, and Cordray (1981b) as cited by Sun, “showed that addition of salt at all levels increased thiobarbituric acid (TBA) values and decreased color levels.”  No such effect has however been noticed with heat treated, smoked and cured meat.

Salt and phosphates during the mixing/ tumbling step are essential in that it aids the extraction of myofibrillar proteins which in turn aids in the overall binding.  (Pearson and Gillett, 1999)

The interaction of salt and TG is a key consideration.  Sun reports that “in cooked restructured meat products, gel firmness and water-holding capacity (WHC) have been reported to increase by the addition of TG in high-salt (2%) products but not in low-salt products (Pietrasik & Li-Chan, 2002b). TG was able to improve consistency (firmness) but not cooking loss of the product in a low salt (1%) system (Dimitrakopoulou, Ambrosiadis, Zetou, & Bloukas, 2005).”  (Sun, 2009)

“Kuraishi et al. (1997) investigated the effect of salt on binding strength and indicated that provided there was addition of salt (NaCl), TG treatment caused effective binding of meat pieces. Their result showed that an increase in binding strength caused by adding salt (1.0–3.0%) with TG when compared to TG alone.”  (Sun, 2009)

PHOSPHATES – BINDING

Phosphate generally enhances the effect of salt.  Sun (2009) reports that “a variety of phosphates in different combinations, concentrations, and with concomitant salt concentrations were evaluated by Trout and Schmidt (1984). They found that tetrasodium pyrophosphate had the greatest binding effectiveness, which was followed by sodium tetrapolyphosphate, and then sodium hexametaphosphate.

They concluded that most of the changes in binding could be explained by the ionic concentration of the phosphates. STP also delays development of rancidity and is added at a level of about 0.25% for adequate protein extraction and flavor development (Pearson & Gillett, 1996). Nielsen, Peterson, and Møller (1995) observed optimum effects of STP on the texture at a concentration of 0.2%. (Sun, 2009)

COMBINATION OF STROMAL PROTEINS WITH ALGIN/ CALCIUM OR TG

I include this in a separate heading, due to the low-cost stromal proteins of collagen, elastin, and reticulin and muscles with a high percentage of it.  The protein is of huge interest in TG formulations.  How will the inclusion of pork gelatin aid the binding system with TG?

In considering connective tissues, it is astounding to recognise the monumental presence of K. B. Lehmann.  In terms of the curing reaction in meat, it was this German hygienist and bacteriologist from the Hygienic Institute at Würzburg, Germany who confirmed Polenski’s suspicions (Saltpeter) that nitrite is the key in the cured colour formation and not nitrate as was believed.  He further importantly identified its colour spectrum when diluted in alcohol.  (Fathers of Meat Curing)  It was probably based on his work and that of his student, Karl Kißkalt, that the German government allowed the use of nitrite in curing brines during the first world war.

It was Lehmann and his coworkers who showed that “the toughness of different cuts of meat, measured mechanically, was closely related to their content of connective tissue, and that the decrease in toughness resulting from cooking was related to the collagen of connective tissue rather than to the elastin.”  (Mitchell, et al.; 1926)

They found that “under the influence of moist heat the collagen is readily changed to gelatin, thus losing its toughness. In the raw condition, white fibrous connective tissue (mainly collagen) is almost twice as tough as yellow elastic connective tissue (mainly elastin), but when cooked, the former loses most of its toughness while the latter remains practically unchanged in this respect.”  (Mitchell, et al.; 1926)

“Ensor, Sofos, and Schmidt (1990) concluded that the use of high-connective-tissue meat or addition of concentrated forms of connective tissue in algin/calcium gel restructured meats could improve product texture and reduce formulation costs.”  (Sun, 2009)  Gelatin is the ideal thickening agent to accompany transglutaminase since it contains a variety of different amino acids, including our old friends Glutamine and Lysine which are now cross-linked by the action of transglutaminase.  (Aguilar, M. R. and Román, J. S.; 2014:  186)  It is important to use the right kind of gelatin.  Fish and pork gelatin will be objectionable for either religious or allergen concerns by various processors in various parts of the world and it is an important consideration.

I am aware of tests underway in Chili where pork protein is tested in conjunction with TG to replace MDM.  The viability of this must be tested.

WHAT ABOUT FAT?

We skipped over fat when we looked at the constituents of muscles and now returns to it.  Many people refer to fat as lipids, but fats are only a subgroup of lipids called triglycerides.  Lets set some basic concepts up, to begin with.  Human body fat, animal, and vegetable fats have triglycerides as its main constituent.  Their function in blood is to facilitate bidirectional transference of adipose fat which is the fat layer under our skin, around internal organs), in bone marrow, intermuscular and in the breast tissue.  

Let’s look closer at the adipose tissue.  It is “composed of a loose collection of specialized cells, called adipocytes, embedded in a mesh of collagen fibers.  We looked briefly at collagen when we reviewed the stromal proteins.  The main role of adipose tissue in the body is its role as a fuel tank for the storage of lipids and triglycerides.

One gets white and brown adipose tissue with white tissue being the most numerous.  “The main role, or function, of white adipose tissue is to collect, store and then release lipids.  However, because of the properties of the lipids being stored, the adipose tissue also acts as a protective cushion (resists knocks) and also as a layer of insulation against excessive heat loss.

Lipids conduct heat very poorly (only about a third of the rate of other materials) so even a small layer of adipose cells (about 2 mm) will keep a person warm at 15 degrees centigrade, whereas a person with only a 1 mm layer of protection will be feeling quite uncomfortable.

About 80% of average white adipose tissue is lipid, and of that, about 90% is made up of the six triglycerides: stearic, oleic, linoleic, palmitic, palmitoleic and myristic acid.  Also stored are free fatty acids, cholesterol, mono- and di-glycerides.”  (brooklyn.cuny.edu)

“Each adipocyte cell has a large, central, uniform, lipid packed central vacuole which, as it enlarges, pushes all the cytoplasm, the nucleus, and all the other organelles to the edge of the cell, making it look a bit like a band or ring under the microscope.

These cells can vary in size from about 30 microns to over 230 microns, and, despite their distorted appearance, contain all the necessary biochemical machinery of other cells.

Every adipose cell must touch at least one capillary or blood vessel (an artery or vein).  From this the cells draw all their needed supplies, including lipids.

Fatty foods, with high lipid content, often provide more lipids than can be digested and used right away.  The excess is stored in the adipose tissue.  Excess carbohydrate and protein taken in with meals can also be converted to fat (usually in the liver) and then moved to the adipose tissue for longer-term storage.

Lipids are the major fuel reserve for humans and most mammals.  These molecules are very efficient at storing needed energy.  One gram of fat stores about 9 kcal per gram, compared to carbohydrate or protein (4 kcal per gram).  For mobile animals, this means that less bulk has to be carried around and a normal sized body that is about 20% fat has enough stored energy to last about 20 – 30 days without eating!”  (brooklyn.cuny.edu)

Let’s look more closely at triglyceride.  There are many types of triglycerides.  We are all familiar with the two main groups of triglycerides, namely saturated and unsaturated types. Saturated fats are “saturated” with hydrogen — all available places where hydrogen atoms could be bonded to carbon atoms are occupied. the importance to us for meat processing is its melting point which is higher and are more likely to be solid at room temperature.  It is this saturated fats that, when ingested, raises the level of cholesterol in your blood.  (daa.asn.au)

On the other hand are the unsaturated fats which have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. For our purposes, the net result is that they have a lower melting point and are more likely to be liquid at room temperature.  These fats help reduce the risk of high blood cholesterol levels and have other health benefits when they replace saturated fats in the diet. (daa.asn.au)

When one works with pork fat, it is important to keep an eye on the temperature.  During processing, highly unsaturated fats will start to melt and form a fat coating on the product which is visually unappealing. (Toldra, 2010)  Beef fat is firmer with a more intense flavour in comparison with pork or chicken.  Beef fat’s melting point is comparable to pork kidney fat due to the low content of collagen and saturated fats.  The reason why pork fat is popular is that it is largely tasteless and flavourless.  The rules for making meat emulsions are based on fat choice and temperature. “Pork backfat gives the best suitable product for slicing.  Jowl and belly fat can also be used.  The endpoint chopping temperature should remain below 18 deg C, 12 deg C, and 8 deg C for beef, pork, and poultry fat respectively to avoid fat melting.”  (Toldra, 2010)

“To make spreadable products fat must be dispersed in the liquid state at “hot” temperatures.  The endpoint chopping temperatures should be above the fat melting point (i.e., 35 deg C).  To achieve this final temperature, fat is usually pouched in water at temperatures above 80 deg C before being mixed with protein (liver or lean meat).  The object is to reach a final internal temperature between 50 and 60 deg C for ham fat and between 70 and 75 deg C for jowl fat.  Fat poaching also causes contraction of the connective tissue which will facilitate the grinding; it eliminates low melting fats, which can cause weight losses during cooking and it lowers the microbial content.  Thus, for hot emulsions, low melting fat is preferred such as ham and jowl fat remain firm during cooking at high temperatures.”  (Toldra, 2010)

Triglycerides are composed of three fatty acids.  The fatty acid content in animals depends on age, type of feed and the environment.  Diet plays an important role, especially in pork which is one of the reasons why pork, raised in informal settlement environments are very poor substitutes for commercially farmed animals where feed are strictly controlled.   The properties of the fat will generally be determined by the composition of the fatty acids.  “It will be soft (oily appearance) and prone to oxidation when there is a high percentage of polyunsaturated fatty acid linoleic (typical of feed rich in corn, for instance) and linolenic acids.”  (Toldra, 2002)

There are two main groups of lipids in the body.  The one is triglycerides which we just had a look at.  The other is phospholipids.  They are present in very small amounts but have a strong key role in flavour development and the oxidation of postmortem meat.  They also have a relatively high proportion of polyunsaturated fatty acids in comparison to neutral lipids.  Some of the major constituents are phosphatidylcholine (lecithin) and phosphatidylethanolamine.  Phospholipids vary depending on the genetic type of the animal and anatomical location of the muscle.  Therefore, the amount of phospholipids tends to be higher in red oxidative muscles than in white glycolytic muscles.  (Toldra, 2002)

The interaction of fat and protein is a very important consideration in restructuring meat. “The fat level clearly influenced the structure of the gel/ emulsion network, as reflected by the differences in the type of protein molecular interactions involved in its formation, and this, in turn, affected the fat binding properties and the texture of the end product.” (Sun, 2009)

It is difficult to bind fat effectively to meat.  De NG, Toledo, and Lillard (1981) found that water and fat binding by meat batters diminish when temperatures exceed 16°C during comminution.  This speaks directly to the preparation of stuffing meat and it requires for the meat temperature to be kept as low as possible, but not so low that it makes it impossible for workers to use it in the restructuring process.

Secondly, when one talks about fat and stuffing meat, one must consider the interaction between a TG blend containing pork gelatin and fat in the meat mix which is less than optimal.  TG by itself is not a good binder for fat.  The easiest way of handling fat in stuffing meat is to avoid it.  I have found pork fillet to be particularly suited due to its lean nature.

Remember that gelatin “works by creating a very fine mesh of proteins, between which the (hydrophilic) liquid gets trapped.  A mixture of fat and water isn’t a liquid. It can be either a rough two-phase mixture, with visible fat droplets swimming around in the water, or it can be an emulsion, with invisibly small fat droplets dispersed through the water. Emulsions appear smooth, e.g. milk.”  (cooking.stackexchange.com)  Fat in the stuffing meat will interfere with the binding.

As far as the whole meat muscles are concerned, it is important to lay the meat pieces fat down in the mold to minimize contact between added meat and fat.

FREEZING/ CHILLING

After thermal treatment, the meat must be frozen as soon as possible.

Sun (2009) reports that “although most of the studies using TG for restructuring meat conducted by incubation meat at optimum temperature (37–508C) of MTG or by cooking to obtain sufficient binding strength, some researchers obtained good binding effect by using cold binding (2–58C), with the combination of TG and sodium caseinate, without addition of salt or cooking (Kuraishi et al., 1997; Serrano, Cofrades & Jimenez Colmenero, 2004). Kuraishi et al. (1997) indicated that the TG reaction condition of 58C for 2 h would not enable any bacteria present to increase much and discoloration of the meat was not observed in the raw, refrigerated state. In my experience, IT binds very well at lower temperatures.

The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity.  Optimal pH for commercial TG was found to be between pH 5.5 and 6.0. (Ceresinoa, 2018)

DIFFERENT BACTERIA PRODUCE TG WITH DIFFERENT PROPERTIES

It has been found that different strains of bacteria that produce the enzyme TG, produce it with different yield and properties.  Different TG producing bacteria strains are still being identified from different environments. “The isolation of a strain of Streptomyces mobaraense was the first step towards the extensive commercial exploitation of this enzyme. Thereafter, a number of various microbial strains, such as Streptomyces lydicus, Streptomyces cinnamoneum CBS 683.68, Streptomyces sp. CBMAI 837, have been found being able to biosynthesize TG extracellularly.  How the TG is produced definitely impacts its application.  TG’s of various origins and in different concentrations have different functionality.  (Ceresinoa, 2018)

Generally, increased TG concentration produces a better binding of meat.  The optimum pH for the commercial TG was found to be between pH 5.5 and 6.0, but TG from different strains have a different optimal pH.  TG from Bacillus circulans BL32, for example, has been reported to have an optimal pH of 7.2.  (Ceresinoa, 2018)

“As to temperature influence on TG activity, minor differences were seen between the enzymes, with a maximum activity observed at 40 °C for the commercial TG and at 35–40 °C for SB6. At temperatures above 45 °C, both enzymes suffered a rapid drop in their activities.  These findings are consistent with studies of TG derived from other streptomycetes such as Streptomyces hygroscopicus and Streptomyces sp. CBMAI 837. (Ceresinoa, 2018)

DEBONING

Sinew and excess fat must be removed in the trimming stage to maintain product quality and consistency.  The use of a grid system allows the deboning department to trim to exact product specifications.  In regular bacon production, leaving the silverskin and membrane on the meat is advisable since it will prevent excess moisture loss during thermal processing.  In a restructuring scenario, it will have to be removed during trimming because it will interfere with the binding.

WHAT ABOUT PSE MEAT?

PSE pork meat is a scourge in the Western Cape during the summer and using TG does not resolve PSE.  An excellent article on an evaluation of factors impacting on meat quality in relation to PSE is Differentiation of pork longissimus dorsi muscle regarding the variation in water holding capacity and correlated traits.

It is possible to address PSE.  The first option will be so source meat during the summer from non-Western Cape sources, but this presents difficulty for the farmers who are the backbone of the industry and may go against strategic alliances.  A second strategy will be to work closely with farmers and the local abattoirs because much can be done pre and immediate post slaughtering.  These are, however matters that are notoriously difficult to implement.

What can be done from a processing perspective? Motzer, Carpenter, Reynolds, and Lyon (1998) successfully used pale, soft and exudative pork to manufacture restructured hams.  The problem with producing bacon from PSE meat is that “due to the rapid pH drop while muscle temperature remains high, the proteins in the myofibrillar fraction become partially denatured and lose their functionality.  Denaturation of myosin in PSE muscle ultimately affects the water holding capabilities of the meat system. As a consequence, products manufactured with PSE may be expected to lose higher amounts of water.”  (Motzer, et al., 2006)  The unfortunate reality is that 100% PSE meat cannot be utilized in high quality processed products (Marriott, et al. 2006).

Motzer and coworkers (2006) report on Shand et al. (1994) who evaluated the effects of various levels of salt, temperature and kappa carrageenan on the bind of structured beef rolls and reported that as salt or levels of kappa carrageenan increased, the bind increased.  They found that kappa carrageenan was the only binder different that when adequately solubilized improved adhesion of PSE meat.

As far as water holding capacity, they found that adding modified food starch (MFS) and isolated soy protein (ISP), enhanced the water holding capacity of hams produced from PSE pork meat.  They noted that isolated soy protein (ISP) “resulted in a thicker adhesion than normal for the meat pieces. Manual stuffing became difficult and often resulted in air pockets within the meat log.”  (Motzer, et al., 2006)  This will, however, be overcome by a proper press system.

Even though there were improvements in the ham, the fact remained that “due to loss of structural integrity, PSE meat will lose considerable water “, especially after thermal processing.  Most of the water is released due to the partially denatured myofibrillar proteins.”  (Motzer, et al., 2006)

The complete article can be found at PSE Meat Treatment.  Without reformulating a brine for the summer in Cape Town, incorporating kappa carrageenan, MFS, and ISP, losses in bacon production will remain material for pork procured locally.  It will manifest in excessive purge in the final product stage, excessive moisture loss during and after thermal processing and poor binding of restructured parts of the bacon logs.

Of course, a strategy will be to produce ham with the badly affected meat.  “Motzer et al. (1998) revealed that utilizing 50% PSE pork in a restructured product with either modified food starch or carrageenan yielded better quality pork than 100% PSE treatments.  Schilling et al. (2002) later demonstrated that combining 25% PSE and 75% RFN (red, firm, and non-exudative) pork in a chunked and formed ham was similar in quality to a 100% RFN pork sample when soy protein concentrate and modified food starch were incorporated together at 2 and 1.5%, respectively. Similarly, Torley et al., (2000) reported that increasing the ionic strength and utilization of polyphosphates resulted in increased cooking yield similar to that of a product manufactured from RFN pork.”  (Marriott, et al. 2006)

It is my suggestion that all these be tested in a summer mix of products to compensate for the extraordinary level of PSE prevalent in regions like the Western Cape during the summer.  “This research makes it clear that PSE pork can be incorporated into processed products, but it can be unsatisfactory to use formulations with more than 25% PSE. Samples formulated with 25% PSE pork exhibit acceptable texture, but those formulated with 75 or 100% PSE often sustain cracking.”  (Marriott, et al. 2006)  This relates to cooked hams. Bacon is a different matter and mixing PSE and non-PSE meat cannot be part of the solution. Producing hams instead of bacon with such meat is an option.

The bottom line is that solutions exist and an effective strategy is possible but will require focus and cooperation.

INCLUSION OF OTHER PRODUCTS

I have for some time considered the inclusion of a  blood-based binding system with TG which “can be used for binding comminuted and large pieces of meat (Boles & Shand, 1998, 1999). The binding mechanism of restructured meats is based on the blood clotting action between fibrinogen, thrombin, and TG. Cross-linking and gelation between fibrin itself and between meat collagen and the fibrin are induced by TG (Sheard, 2002).”  (Sun, 2009).

Other products to consider for inclusion are crude myosin, extract, surimi (Chen, Huffman, & Egbert, 1992), egg white powder, raw egg white, egg powder, bovine, porcine, lamb, broiler plasma powders, broiler breast meat powder, gelatine (Lu & Chen, 1999), dried apples, corn crumbs, mushrooms (Marriott, Graham, Schaffer, & Boling, 1986c), rice bran oil and fiber (Kim, Godber, & Prinaywiwatkul, 2000), and walnut (Jime´nez Colmenero et al., 2003; Serrano et al., 2006).

CONCLUSION

TG represents one of the most exciting developments in meat processing from the perspective of the large-throughput meat factories.  The optimal utilization of the technology is still in its infancy, despite the many decades that passed since it was first made available from the shores of Japan.

References:

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Ceresinoa, E. B.,  de Meloa, R. R.,  Kuktaiteb, R.,  Hedenqvistc, M. S., Zucchid, T. D.,  Johanssonb, E.,  Satoa, H. H..  2018.  Transglutaminase from newly isolated Streptomyces sp. CBMAI 1617:  Production optimization, characterization and evaluation in wheat protein and dough systems.  Food Chemistry 241 (2018) 403 – 410. Science Direct, Food Chemistry.

Chattopadhyay S, Raines RT.  2014. Collagen-Based Biomaterials for Wound Healing. Biopolymers. 2014;101(8):821-833. doi:10.1002/bip.22486.
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Bacon and the art of living 15: Concerning the direct addition of nitrite to curing brine

by Eben van Tonder

This article is available for download in pdf: Concerning the direct addition of nitrite to curing brines

ebenvt bacon belly ebenvt Prague Powder

Introduction

Bacon and the art of living is a study in the birth of the elements of bacon curing.  Neither the chemical reactions, nor the different mechanical processes are simple.  Everything about bacon is complex and beautiful.  One of the most amazing stories within the grand story of bacon, is the story of sodium nitrite.

Pork is changed into bacon by the reaction of nirtrite (NO2-).  With salt, it is the curing agent.  The meat industry uses nitrite in the form of an ionic compound, sodium nitrite.  It is sold as Quick Cure or Insta’ Cure, Prague Salt, Prague Powder or simply Pink Salt or Curing Salt.  It is coloured pink to distinguish it from ordinary salt (sodium chloride).  Every spice company sells it.  It is the essential ingredient in the meat curing process.

Meat changes colour from the red fresh meat colour to an unappetising brown colour within days. (1)  If one injects nitrite into the meat or rubs a mixture of salt and a small percentage of nitrite onto it, the meat will develop an appatizing reddish/ pinkish fresh meat colour (Hoagland, Ralph.  1914) and a characteristic cured taste.  It will retain this colour for weeks and months if packed in the right conditions.  (1)  Nitrite provides an indispensable hurdle against a particularly nasty food pathogen, clostridium botulinum.  It also endows the meat with a distinct cured taste.

During ages past, it has however not been nitrite that was added to meat to accomplish this, but its cousin, nitrate (NO3-).  They may be cousins, but are very different in characteristics. Nitrate takes several weeks or even months to cure meat where nitrite accomplishes the same task in 12 hours.  How the change happened from using nitrate or salpeter in meat curing to nitrite is an epic story.

Overview

This article tracks the migration of the meat industry from the use of saltpeter (potassium or sodium nitrate) as curing agent to sodium nitrite.  It gives an overview of the scientific discoveries which started to reveal the mechanisms of meat curing.   This understanding lead to the realisation that a direct application of nitrite as the curing agent will be vastly superior to the use of saltpeter (nitrate).

This was a dramatic discovery since in the late 1800’s and early 1900’s, the world saw nitrite as a dangerous drug at best and a poison that polluted drinking water and cause death of cattle.  Using this directly in food and meat curing was unthinkable.

Sodium nitrite was available in this time for application in the coal-tar dye and medical industries.  Science and engineering have however not worked out its large scale production in a way that will make it a commercially viable proposition for direct use in meat curing from a price and availability perspective.

World War One provided the transition moments required to change everything.  Germany invested heavily in nitrogen related technology for the war.  The most organised scientific and engineering environment on the planet in the early 1900’s focused its full attention on overcoming the manufacturing challenges in the service of the manufacturing of munitions.  It also required this technology to overcome the challenge of being cut off, as a result of the war, from the natural sodium nitrate deposits in Chili that it required as fertilizer to drive its enormous agriculture sector during the war.  At the same time, the use of saltpeter in meat curing was prohibited under the leadership of Walther Rathenau so that the valuable nitrate could be reserved for manufacturing of munitions.

This prohibition, I believe, was the initial spark that caused butchers to change to the use of sodium nitrite.  At the same time, sodium nitrite was being produced in large volumes since it had, in its own right, application in the manufacturing of explosives.  Health concerns and probably the need to have it reserved for munitions, lead to a ban, similar to nitrate, on its use in meat curing.  So, World War One solved the scientific challenges of large scale manufacturing of sodium nitrite, the engineering challenges of building production facilities and provided the impetus for the meat industry to change by banning the use of saltpeter in meat curing.  The ban was lifted after the war.

Following the war, Germany had to find markets for its enormous war time chemical stock piles.  One of the ways it “sold” sodium nitrite was as a meat curing agent based on its inherent benefits of curing consistency and the vastly shorter curing time required.

It was introduced to the world mainly through the Chicago based firm, Griffith Laboratories, who imported it as Prague Salt from Germany and later improved on it by fusing the sodium nitrite to sodium chloride and sold it as Prague Powder.

Early humans to Polenski (1891)

Early humans did not know they added nitrate to the meat.  A mixture of salt and a small amount of saltpeter was used to cure meat in order to preserve it and to retain the fresh meat colour.

Saltpeter is found naturally around the world in typically dry areas.  Deposits exist in India, China, Mexico, the USA, and the Middle East.  Despite its wide occurrence, the concentration of natural saltpeter is low.  (Whittaker, CW, 1932: 10)

Saltpeter is also made by human effort.  Europe, particularly Germany and France, Great Britain, India and the United States all acquired the technology to produce satpeter.  (Van Cortlandt, P, 1776:  7, 8)

In South Africa, saltpeter deposits are found in the Griquatown beds of the Transvaal geological system.  It extends from just South of the Orange River Northwards to the Kalahari Desert and then Eastwards into the Old Transvaal from Zeerust to Polokwane. The nitrate deposits occur in the middle portions of these beds, in softer and more decomposed shale.  These South African reserves have fortunately never been mined even though it was used on a small scale to make gunpowder for the old Boer government.  (Whittaker, CW, 1932: 10)

Saltpeter was at the heart of the arms race of the middle ages.  It was used mainly in gunpowder, but as the worlds population grew, it became indispensable as a fertilizer and for curing meat. (See Bacon and the art of living, chapters 2, 3 and 4)

The French chemist, Antoine Lavoisier worked out its chemical composition.  It is an ionic compound consisting of the metal potassium and its power is nitrate.  Potassium Nitrate.  (Mauskopf, MSH.  1995:  96)  Trade in Saltpeter around the world was done through companies such as the Dutch East Indian Company (Dutch abbreviation, VOC) who traded it for its main use as an ingredient in gunpowder.  It was by volume one of the largest commodities traded by the Dutch East Indian Company who set up the trading post in 1652 that became Cape Town.  

Major developments shifted the balance of power away from Indie, China and home grown saltpeter production to South America where huge deposits of sodium nitrate were discovered that would become the principal source of the worlds nitrate for much of the 1800’s.

A man walks down a dirt road in the Atacama Desert. Despite being one of the most inhospitable places on earth, the Atacama is still mined: in 2010 this made world-wide news, when the Copiapó mining accident led to the dramatic rescue of 33 trapped miners (AP Photo/Dario Lopez-Mills).
A man walks down a dirt road in the Atacama Desert. Despite being one of the most inhospitable places on earth, the Atacama is still mined: in 2010 this made world-wide news, when the Copiapó mining accident led to the dramatic rescue of 33 trapped miners (AP Photo/Dario Lopez-Mills).

A popular legend tells the story of the discovery by two Indians in the Atacama desert in the South of Peru.  According to the legend, after a hard day’s work, they camped in the Pampa and started a campfire to warm themselves.  All of a sudden the ground started to burn and they ran away, thinking that they have seen the devil.  They reported the event later to a priest in Camina who returned to the site.  He had it analysed and found it to contain sodium nitrate (the same power as potassium nitrate, but linked to another common metal).  The priest, according to the story, threw the rest of the soil in the courtyard of his house and saw the plants grew vigorously.  He recommended the soil as an excellent tonic for the plant kingdom.  (Wisniak, J, et al., 2001 :433)

So was discovered the enormous sodium nitrate deposits of the Atacama desert. The fertilizer properties of the salt was known long before the 1600’s.   There are references to saltpeter and the nitrate ground in 1604.  During the time of the Spanish Conquest, in the 1700’s, miners working in the South of Peru realised that gunpowder could be manufactured from the material in the soil instead of potassium nitrate.  (Wisniak, J, et al., 2001 :433)

A report published in 1803 by Juan Egana, Secretary of the Royal Court of Mines in Chile showed the Huasco region is “covered in a large part by a crust of niter salt, well crystallized, and several inches thick” (Wisniak, J, et al., 2001 :434)

The region was developed and by 1850 exports reached 24 000 tons/ year.  In 1910 it was 2.4 million tons per year and by 1916, 3 million tons per year from 97 plants. (Wisniak, J, et al., 2001 :434)

By the beginning of the 1900’s the country buying the largest quantity of the Chilean saltpeter was Germany (Wisniak, J, et al., 2001 :434) who used it aggressively in their agriculture sector as fertilizer.

There is a close correlation between sodium and potassium nitrate.  Its difficult to distinguish between sodium and potassium nitrate just by tasting it.  Scientists were able to distinguish between the two compounds from the mid 1600’s and knew that sodium nitrate had a much greater ability to attract water (Whittaker, CW, 1932:  3).  This made sodium nitrate a much better curing agent than potassium nitrate.

Nitrite was described in 1864 by the English Physiologist, B. W. Richardson.  He outlined how to manufacture it and its chemical properties.  (Wells, D. A., 1865:  233)  Much earlier, in 1777 the prolific Swedish chemist Scheele, working in the laboratory of his pharmacy in the market town of Köping, made the first pure nitrite. (Scheele CW. 1777)   He heated potassium nitrate at red heat for half an hour and obtained what he recognized as a new “salt.” The two compounds (potassium nitrate and nitrite) were characterized by Péligot and the reaction established as 2KNO3→2KNO2+O2. (Péligot E. 1841: 2: 58–68) (Butler, A. R. and Feelisch, M.)

The technology existed in the 1800’s to not only produce potassium nitrate (salpeter) and nitrite, but to also test for these.

Remember that curing up till 1890 has been attributed to saltpeter (potassium nitrate) or Chilean saltpeter (sodium nitrate).  In 1891 a German food scientist, Dr Ed Polenski, working for the German Department of Health made an observation that would change the world while studying curing brines.  When he tested the curing brine made from saltpeter and salt, days after it was made, he found nitrite to be  present.  This was surprising since saltpeter is potassium or sodium nitrate, not nitrite.

Dr Ed speculated that the nitrate (NO3-) was changed into nitrite (NO2-) through bacterial action, a reduction step between nitrate and nitrite that was well understood by this time.  He had a hunch that nitrite is responsible for curing of meat and not the nitrate directly, as was previously thought.

From Polenski (1891) to WWI (1914 to 1918)

world war 1

Following Dr Ed’s observations in 1891, considerable resources from around the world were dedicated to understand the chemistry of meat curing.

When World War One broke out, the concept of nitrite as curing agent (as opposed to nitrate) was firmly established.

Ralph Hoagland, Senior Biochemist, Biochemie Division, Bureau of Animal Industry, United States Department of Agriculture, published an article in 1914, Coloring matter of raw and cooked salted meats.  In this article, he shows that nitrite as curing agent was a known and accepted fact by the outbreak of World War One (Hoagland, Ralph.  1914)

Readers who dont have an interest in the detailed description of the key discoveries may want to skip over the rest of this section altogether or glance over it generally.  The goal of the section is to give the reader a sense of how firmly and universally the concept of nitrite as the curing agent was established by 1914.  In the midst of the technical names and jargon, don’t lose the sense of the universal interest.  The 1700’s, 1800’s and beginning of the 1900’s was a time when the average person was as interested in chemistry as we are today about communication and information technology.

The difference between nitrates and nitrites, for example, was taught in school curriculum. An article appeared in the Daily Dispatch in Brainerd, Minnesota in the 20’s, that gives as an example of a diligent high school student, that he or she would know the difference.    (The Brainerd Daily Dispatch (Brainerd, Minnesota).  17 January 1923.  Page 3.)

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

Karl Bernhard Lehmann (September 27, 1858 – January 30, 1940) was a German hygienist and bacteriologist born in Zurich.

In an experiment he boiled fresh meat with nitrite and a little bit of acid.  A red colour resulted, similar to the red of cured meat.  He repeated the experiment with nitrates and no such reddening occurred, thus establishing the link between nitrite and the formation of a stable red meat colour in meat. (Lee Lewis, W., 1925: 1243)

In the same year, another German hygienists, K. Kisskalt, confirmed Lehmann’s observations but proved that the same red colour resulted if the meat was left in saltpeter (potassium nitrate) for several days before it was cooked. (Lee Lewis, W., 1925: 1243)

K. B. Lehmann made another important observation that must be noted when he found the colour to be soluble in alcohol and ether and to give a spectrum showing an absorption band just at the right of the D line, and a second band, often poorly defined, at the left of the E line. On standing, the color of the solution changed to brown and gave the spectrum of alkaline hematin, the colouring group (Hoagland, Ralph.  1914).

The brilliant British physiologist and philosopher, John Scott Haldane weighed in on the topic.  He was born in 1860 in Edinburgh, Scotland. He was part of a lineage of important and influential scientists.  (Lang, M. A. and Brubakk, A. O. 2009.  The Haldane Effect)

J. S. Haldene contributed immensely to the application of science across many fields of life.  This formidable scientist was for example responsible for developing decompression tables for deep sea diving used to this day.  (Lang, M. A. and Brubakk, A. O. 2009.  The Haldane Effect)

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

An interesting anecdote is told about him from the time when he was studying medicine  in Jena.  He apparently carefully observed the amount of beer being drunk, noting that the students on the average drank about 20 pints per evening.”  (Lang, M. A. and Brubakk, A. O. 2009.  The Haldane Effect)

Before we look at Haldene’s contribution, let us re-cap what has been determined thus far.

Polenski and Notwang discovered that nitrite were present in a mix of saltpeter and salt, after a while, even though no nitrite were present when the brine was mixed.

Karl Bernhard Lehmann linked nitrite conclusively with the reddening effect of fresh meat that was boiled in a nitrite and water solution with some free acid.  He also showed that this does not happen if fresh meat is placed in saltpeter and water solution and boiled immediately.   K. Kisskalt showed that the same reddening occurred if fresh meat is left in saltpeter for some time.

K. B. Lehmann managed to “isolate” the colour by dissolving it in ether and alcohol and analyze it spectroscopically.

What S. J. Haldele did was to apply the same rigor to cured meat and became the first person to demonstrate that the addition of nitrite to hemoglobin produce a nitric oxide (NO)-heme bond, called iron-nitrosyl-hemoglobin (HbFeIINO). (Lang, M. A. and Brubakk, A. O. 2009:  119)

Nitrite is further reduced to nitric oxide (NO) by bacteria or enzymatic reactions and in the presence of muscle myoglobin forms iron-nitrosyl-myoglobin. It is nitrosylated myoglobin that gives cured meat, including bacon and hot dogs, their distinctive red color and protects the meat from oxidation and spoiling. (Lang, M. A. and Brubakk, A. O. 2009: 119)

This is how he did it.  He concluded (1901) that its red colour is due to the presence of the nitricoxid hemochromogen resulting from the reduction of the coloring matter of the uncooked meat, or nitric-oxid hemoglobin (NO-hemoglobin). (Hoagland, Ralph.  1914)

Remember the observation made by K. B. Lehmann that the colour of fresh meat cooked in water with nitrites and free acid to give a spectrum showing an absorption band just at the right of the D line, and a second band, often poorly defined, at the left of the E line.  (Hoagland, Ralph.  1914)

Haldene found the same colour to be present in cured meat.  That it is soluble in water and giving a spectrum characteristic of NO-hemoglobin. The formation of the red color in uncooked salted meats is explained by the action of nitrites in the presence of a reducing agent and in the absence of oxygen upon hemoglobin, the normal coloring matter of fresh meats. (Hoagland, Ralph.  1914)

Ralp Hoagland (1908) studied the action of saltpeter upon the colour of meat and found that its value as an agent in the curing of meats depends upon the nitrate’s reduction to nitrites and the nitrites to nitric oxid, with the consequent production of NO-hemoglobin.  The red colour of salted meats is due to this compound.  Hoagland conclusively shows that saltpeter, as such, has no value to preserve the fresh colour. (Hoagland, Ralph,  1914: 212)

The reason why the knowledge did not translate to a change in curing brines was very simple.  The technology and infrastructure did not exist to produce enough nitrite commercially to replace saltpeter.  This means that to produce nitrite was very expensive.

There were some attempts to capitalise on the knowledge gained.  The German scientist,  Glage (1909) wrote a pamphlet where he outlines the practical methods for obtaining the best results from the use of saltpeter in the curing of meats and in the manufacture of sausages. (Hoagland, Ralph,  1914: 212, 213)

Saltpeter can only effect the colour of the meat if the nitrate in the saltpeter is reduced to nitrite.  Glage gives for the partial reduction of the saltpeter to nitrites by heating the dry salt in a kettle before it is used.  It is stated that this partially reduced saltpeter is much more efficient in the production of color in the manufacture of sausage than is the untreated saltpeter. (Hoagland, Ralph,  1914: 212, 213)

The fear of nitrites

The lack of a large scale production process for sodium nitrite and the engineering to build these plants were however not the only factors preventing the direct use of sodium nitrite in meat curing brines.  As one review literature from the late 1800’s and early 1900’s, one realises that a major hurdle that stood between the use of sodium nitrites in meat curing was the mistrust by the general public and authorities of the use of nitrites in food.  The matter relate to the high level of toxicity of nitrite, a matter that will be dealt with separately in Bacon and the art of living.

The first recorded direct use of nitrite as a curing agent was in 1905 in the USA where it was used in secret. (Katina, J.  2009)   The USDA finally approved its use as a food additive in 1906. (porkandhealth)  This did not mean that the public would accept it.

Sodium Nitrite started to be used in this time as a bleach for flour in the milling industry.  Several newspaper articles reveal public skepticism and the great lengths that the scientific community and industry had to go to in order to demonstrate its safety as a bleaching agent  for flour.  An article appeared in The Nebraska State Journal Lincoln, Nebraska on 29 June 1910 entitled,  “All for bleached flour.  No harm can come from its consumption says experts”.  The article deals with a federal court case about the matter and interestingly enough, it seems from newspaper articles that the government was opposing its use.  Many other examples can be sited.

There is a 1914 reference in the London Times that shows the general view of nitrite as not just restricted to the USA.  The article appeared on 9 June 1914 and a reference is made to sodium nitrite where it is described as “a dangerous drug with a powerful action on the heart.”  (The London Times. 1914.  Page 118)  The reference was to the use of nitrite for certain heart conditions.

It is interesting that sodium nitrite did not find an immediate application in the meat industry, even after it was allowed in 1906 in the USA.

In my view, this points to problems surrounding availability and price.  If the issue was the public perception alone, this could have been overcome with a PR campaign by the meat industry as was successfully done by the milling industry.

On 13 Dec 1915 George F. Doran from Omaha, Nebraska,  filed an application for a patent for a curing brine that contained nitrites.  His application strengthens the evidence that it was not the knowledge of nitrite and its role in curing that was lacking, but availability and price.  He states the objective of his patent application to “produce in a convenient and more rapid manner a complete cure of packing house meats; to increase the efficiency of the meat-curing art; to produce a milder cure; and to produce a better product from a physiological standpoint.”

One of Doran’s sources of nitrite is “sterilized waste pickling liquor which he [I have] discovered contains soluble nitrites produced by conversion of the potassium nitrate, sodium nitrate, or other nitrate of the pickling liquor when fresh, into nitrites. . .”   “Waste pickling liquor is taken from the cured meats.  Nitrites suitable for use in carrying out the present invention may be produced by bacterial action from nitrates and fresh pickling liquor by adding a small percentage of old used pickling liquor. The bacteria in old pickling liquor are reducing bacteria and change nitrates to nitrites.”  (Process for curing meats. US 1259376 A)

The use of old pickle has been described much earlier than Doran’s patent.  His usage of old pickle when he understood the reduction of nitrate to nitrite and nitrite’s role in curing along with the fact that sodium nitrite was available can point to only one reason – price.   It comes 10 years after sodium nitrite was first tested in curing brines for meat and shows that it has never become the curing agent of choice most probably due to limited availability and price.  Much more about this later.

The post WWI era (1918 and beyond)

US troops marching

After WWI something changed.  Saltpeter (potassium or sodium nitrate) has been substituted by the direct addition of nitrite to the curing brines.

The question is who pioneered this.  Why and how did sodium nitrite production become so commonplace that it became available to bacon curing plants around the world?

Industry developments like this do not happen “by itself.”  Someone  drives it in order for it to become general practice in an industry.

Chilean Saltpeter is a good case in point.  Even though natural sodium nitrate deposits were discovered in the Atacama desert, it took a considerable effort on the side of the producers (mainly the Chilean Government) to work out the benefits of sodium nitrate and to market it to the world.  It is, for example, famously reported that the first shipment to Britain was dumped in the sea before the ship docked on account that the cargo attracted customs duty and the ships owners could not see any commercial application for sodium nitrate. (2)

In the same way, the direct application of nitrite in curing brines must have been driven by someone.

The Griffith Laboratories, Inc.

The Chicago based company of Enoch Luther Griffith and his son, Carroll Griffith started to import a mixture of sodium nitrite and salt as a curing substitute for saltpeter from Germany in 1925.  The product was called Prague Salt (Prague Powder, 1963: 3)

The Griffith Laboratories (3) played a key role in marketing the new curing brine in the USA.    They took the concept of the Prague Salt (sodium nitrite) and in 1934 announced an improved curing brine, based on the simple use of sodium nitrite, where they fuse nitrite salt and sodium chloride in a particular ratio.  They called it Prague Powder.  Their South African agents, Crown Mills (4), brought the innovation to South Africa. (Prague Powder, 1963: 3, 4)

It is fair to assume that if Prague Salt was being sold to Griffith in the 1920’s, the German producers must have sold it to other countries and companies around the world also.

The benefits of Prague Salt and later Prague Powder over Saltpeter is dramatic.  Prague Salt (sodium nitrite) does not have the slightly bitter taste of saltpeter (Brown, 1946:  223).  It allows for greater product consistency since the same percentage of nitrate was not always present in the saltpeter and the reduction of nitrate to nitrite takes longer or shorter under various conditions (Industrial and Engineering Chemistry, December 1925: 1243).  The big benefit was however in the curing time required.  Instead of weeks or even months that is required with saltpeter, curing could now be done in days or even hours with sodium nitrite.  (The Food Packer, 1954:  64)  From there, brand names like Quick Cure or Instacure.

This means that we have narrowed the time line for invention of Prague Salt (Sodium Nitrite) to between 1914, the beginning of the Great War and 1925 when Griffith imported it from Germany.

However, a document, published in the USA in 1925 shows that sodium nitrite as curing agent has been known well before 1925.

The document  was prepared by the Chicago based organisation, The Institute American Meat Packers and published in December 1925.  The Institute  started as an alignment of the meat packing companies set up by Phil Armour, Gustavus Swift, Nelson Morris, Michael Cudahy, Jacob Dold and others with the University of Chicago.

A newspaper article about the Institute sets its goal, apart from educating meat industry professionals and new recruits, “to find out how to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.”   (The Indiana Gazette.  28 March 1924).

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

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

Sodium Nitrite curing brines would therefore have arrived in the USA, well before 1925.

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

Griffith describes the introduction and origin of Prague Salt and later, Prague Powder as follows in official company documents:

The mid-twenties were significant to Griffith as it had been studying closely a German technique of quick-curing meats.  Short on manpower and time, German meat processors began curing meats using Nitrite with salt instead of slow-acting saltpeter, potassium nitrate. This popular curing compound was known as “Prague Salt.”  (Griffith Laboratories Worldwide, Inc.)

The World War One link

The tantalizing bit of information from Griffith sets World War One as the background for the practical and large scale introduction of direct addition of nitrite into curing brines through sodium nitrite.

There has to be more to the reason for saltpeter being replaced by sodium nitrite as curing agent than the reasons given by Griffith.  For starters, the meat industry has always been under pressure to work fast with less people due to pressure on profit margins.  The need to cure meat quicker due to short manpower and time as a result of the war could not be the full story.

The World War One link from Griffith does not give all the answers, but it puts the introduction of sodium nitrite to meat curing between 1914 and 1918, at least 7 years before Griffith started to import Prague Salt.

A document from the University of Vienna would fill out the story.  According to it, saltpeter was reserved for the war effort and was consequently no longer available as curing agent for meat during World War One. (University of Vienna). It was reserved for the manufacturing of explosives, and for example, the important industry of  manufacturing nitrocellulose, used as base for the production of photographic film, to be employed in war photography.  (Vaupel, E.,  2014: 462)  It gets even better.  Not only did the prohibition on the use of saltpeter expand the information from Griffith as to why people started using sodium nitrite (macro movements in culture does not take place because of one reason only), but it provide a name to the prohibition.

In August 1914, the War Raw Materials Department (Kriegsrohstoffabteilung or KRA) was set up under the leadership of Walther Rathenau.  It was Rathenau who was directly responsible for the prohibition on the use of salpeter.  (5)  He therefore is the person in large part responsible creating the motivation for the meat industry in Germany to change from saltpeter to sodium nitrite as curing medium of choice for the German meat industry during Wold War One.

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

Atmospheric Nitrogen

One of the most important scientific riddles to be solved in the late 1800’s/ early 1900’s was how to produce ammonia and its related chemicals from atmospheric nitrogen.  Sir William Crookes delivered a famous speech on the Wheat Problem at the annual meeting of the British Association for the advancement of Science in 1898.

In his estimation, the wheat production following 1897 would seriously decline due to reduced crop yields, resulting in a wheat famine unless science can step in and provide an answer.  He saw no possibility to increase the worlds wheat yield under the prevailing agricultural conditions and with the increase in the world population, this posed a serious problem.  He said,  “It is clear that we are taxed with a colossal problem that must tax the wits of the wisest.”  He predicted that the USA who produced 1/5th of the worlds wheat, would become a nett importer unless something change.  He pointed to the obvious answer of manure, but observed that all available resources  are being depleted fast.

Sir William saw a  “gleam of light in the darkness” and that “gleam” was atmospheric nitrogen.  (Otago Witness.  3 May 1900, Page 4)

It was the German Chemist, Fritz Harber who solved the problem, with the help of Robert Le Rossignol who developed and build the required high pressure device to accomplish this. (www.princeton.edu)

In 1909 they demonstrated that they could produce ammonia from air, drop by drop, at the rate of about a cup every two hours.  “The process was purchased by the German chemical company BASF (a coal tar dye supplier), which assigned Carl Bosch the difficult task of scaling up Haber’s tabletop machine to industrial-level production.  Haber and Bosch were later awarded Nobel prizes, in 1918 and 1931 respectively, for their work in overcoming the chemical and engineering problems posed by the use of large-scale, continuous-flow, high-pressure technology.”  (www.princeton.edu)

“Ammonia was first manufactured using the Haber process on an industrial scale in 1913 in BASF’s Oppau plant in Germany.”  (www.princeton.edu)

It was the vision and leadership of Walther Rathenau, the man responsible for restricting the use of saltpeter, that drove Germany to produce synthesized Chilean Saltpeter.  He saw this as one of the most important tasks of his KRA.  He said:  “I initiated the construction of large saltpeter factories, which will be built by private industries with the help of governmental subsidies and will take advantage of recent technological developments to make the import of saltpeter entirely unnecessary in just few months“.  (Lesch, J. E.,  2000:  1)

Fritz Harber was one of the experts appointed by Rathenau to evaluate a study on the local production of nitric acid.

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

So it happened that Germany became the leader in the world in synthesised sodium nitrate production and it effectively replaced its reliance on saltpeter from Chile with sythesised  sodium nitrate, produced by BASF and other factories.

So, as a result of the First World War, sodium nitrite was produced at levels not seen previously in the world and in large factories that was build, using the latest processing techniques and technology from a scientific and an engineering perspective.  Sodium nitrite, like sodium nitrate was being used in the production of explosives.  Nitroglycerin is an example of an explosive used extensively by Germany in World War One that uses sodium nitrite in its production.  (Wikipedia.org.  Nitroglycerin and  Amyl Nitrite)

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

Sodium nitrite and the coal-tar dye industry

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

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

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

Nitrous acid (HONO) is to nitrite (NO2-) what nitric acid (NO3) is to nitrate (NO3-).

According to K. H. Saunders, a chemist at Imperial Chemical Industries, Ltd., Martius was the chemist to whom the introduction of sodium nitrite as the source of nitrous acid was due.   (Saunders, K. H., 1936:  26)

The economic imperative

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

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

The advantage of scale and technology

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

In the USA 7 direct synthesis plants were in operation with a combined capacity of 28 500 tons of nitrogen per year.  (Ernst, FA.  1928: 120)

Supporting evidence from the USA

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

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

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

The Vienna University document indicate that the fast curing of sodium nitrite was recognised and the ban was lifted when the war ended.  It was this fact that Griffith picks up on in their literature.

This is how it happened that sodium nitrite replaced saltpeter as curing salt.

Conclusion

The ban on the use of saltpeter for non military uses by Walther Rathenau is the likely spark that caused butchers to look at alternative curing systems.  A known alternative was sodium nitrite.  Despite a similar ban on the use of nitrite, later imposed for concerns over the safety of nitrite in meat and because sodium nitrite was also used to produce explosives,  it was available in such large quantities around Germany that it was possible to defy the ban. 

The likely consequence of the developments surrounding the production of atmospheric nitrogen is that sodium nitrite was being produced at prices that was previously not possible.  These prices, combined with the volume of sodium nitrite now available made it a viable proposition to replace saltpeter in meat curing and to remain the curing brine of choice, following the war.

Bacon and the art of living Home Page

Notes

(1) “The red color of fresh lean meat, such as beef, pork, and mutton, is due to the presence of oxyhemoglobin, a part of which is one of the constituents of the blood remaining in the tissues, while the remainder is a normal constituent of the muscles. When fresh meat is cooked or is cured by sodium chloride, the red color changes to brown, owing to the breaking down of the oxyhemoglobin into the two constituents, hematin, the coloring group, and the protein, globin.

On the other hand, when fresh meat is cured by means of a mixture of sodium chloride and a small proportion of potassium nitrate, or saltpeter, either as a dry mixture or in the form of a pickle, the red color of the fresh meat is not destroyed during the curing process, the finished product having practically the same color as the fresh meat. Neither is the red color destroyed on cooking, but rather is intensified.” (Hoagland, Ralph.  1914)

(2)   The first export of salitre (sodium nitrate) was authorised by the Chilean government in March 1830 and went to the USA, France, and to Liverpool.  It is the latter shipment which failed and was thrown overboard.  Different sources give different reasons for the action.  One, that price was not attractive,  another, that the excise duties were to high, and a third that the Port captain did not allow the boat to come in because it was carrying a dangerous load.  A few farmers in Glasgow received a few bags.  They used it as fertalizer and reported a three fold increase in crop yield.    (Wisniak, J, et al.  2001:  437)

(3)  Steve Hubbard, Vice President, Global Marketing and Innovation at Griffith Laboratories Worldwide, Inc. graciously provided me with much of the information from company documents.

(4)  Crown Mills was bought out by Bidvest and became Crown National.

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

References:

Baptista, R. J..  2012.  The Faded Rainbow: The Rise and Fall of the Western Dye Industry 1856-2000.  From:  http://www.colorantshistory.org/files/Faded_Rainbow_Article_April_21_2012.pdf

Brown, Howard Dexter et al.  1946. Frozen Foods: Processing and Handling

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

Determination of nitrite in meat products.   University of Vienna, Department of Analytical Chemistry, Food Analytical Internship for nutritionists.

Ernst, FA.  1928.  Fixation of Atmospheric Nitrogen.  D van Nostrand, Inc.

Griffith Laboratories Worldwide, Inc. official company documents.

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

Hwei-Shen Lin.  1978.  Effect of packaging conditions, nitrite concentration, sodium erythrobate concentration and length of storage on color and rancidity development of sliced bologna.   Iowa State University Digital Repository @ Iowa State University

Katina, J. 2009.  Nitrites and meat products.  Czech Association of Meat Processors. http://www.cszm.cz/clanek.asp?typ=5&id=1136

Lang, M. A. and Brubakk, A. O. 2009.  The Haldane Effect.   The American Academy of Underwater Sciences 28th Symposium.Dauphin Island

Lee Lewis, W.  December, 1925.  Use of Sodium Nitrite in Curing Meat.  Industrial and Engineering Chemistry.

Lesch, J. E..  2000.  The German Chemical Industry in the Twentieth Century.  Kluwer Academic Publishers.

Mauskopf, MSH.  1995.  Lavoisier and the improvement of gunpowder production/Lavoisier et l’amélioration de la production de poudre.  Revue d’histoire des sciences

Nitrogen.  University Science Books, ©2011

Otago Witness.  3 May 1900.  Sir William Crookes and the wheat problem.  Issue 2409, Page 4, from:  http://paperspast.natlib.govt.nz/

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

Prague Powder, Its uses in modern Curing and processing.  1963.  The Griffith Laboratories, Inc.

Process for curing meats.  US 1259376 A

Redondo, M. A..  2011.  Effect of Sodium Nitrite, Sodium Erythorbate and Organic Acid Salts on Germination and Outgrowth of Clostridium perfringens Spores in Ham during Abusive Cooling.  University of Nebraska – Lincoln.

Salem, H. et al.  2006.  Inhalation Toxicology, Second Edition.  Taylor & Francis Group, LLC.

Saunders, K. H.  The Aromatic Diazo-Compounds and their technical applications.  Richard Clay and Company.

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

The Brainerd Daily Dispatch (Brainerd, Minnesota).  17 January 1923.  Page 3.

The Food Packer.  Vance Publishing Corporation. 1954

The Indiana Gazette, 28 March 1924

The Indiana Gazette.  28 March 1924.

The Nebraska State Journal Lincoln, Nebraska.  Wednesday, June 29, 1910.   All for bleached flour.  No harm can come from its consumption says experts.  Page 3.  

The Times (London, Greater London).   8 June 1914.  Adulteration.  Examples of fraudulent manufacture.  Page 118

The Times (London, Greater London).  1 May 1919.  Government Property for by direction of the Disposal Board.  Explosives and Chemicals.  Prices were coming down in 1920, as reported in The Cincinnati Enquirer ( Cincinnati, Ohio), 2 July 1920. Page 17.

Van Cortlandt, P, et al.  1776.  Essays upon the making of salt-petre and gun-powder.  Published by order of the Committee of Safety of the colony of New-York.

Vaupel, E.  2014.  Die chemische Industrie im Ersten Weltkrieg
Krieg der Chemiker. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Wisniak, J, et al.  The rise and fall of the salitre (sodium nitrate) industry.  Indian Journal of Chemical Technology.  Vol. 8, September 2001, pp 427 – 438.

Wells, D. A.   1865.  The Annual of Scientific Discovery, Or, Year-book of Facts in Science and Art for 1865.  Gould and Lincoln.

Whittaker, CW, et al.  July 1932.    A Review of the Patents and Literature on the Manufacture of Potassium Nitrate with notes on its occurrence and uses.  United Stated Department of Agriculture.  Miscellaneous Publications Number 192.

http://www.porkandhealth.org/filelibrary/PorkAndHealth/freebies_SodiumNitriteFactSheet.pdf

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Haber_process.html

http://www.britannica.com/EBchecked/topic/491966/Walther-Rathenau

en.wikipedia.org/wiki/Nitroglycerin

http://en.wikipedia.org/wiki/Amyl_nitrite

http://en.wikipedia.org/wiki/Amyl_nitrite

Images:

Picture 1:  Smoker trolly with pork belly taken by Eben

Picture 2:  Curing salt taken by Eben

Picture 3:  Atacama Desert.  Photograph by  Dario Lopez-Mills/AP.  Source:  http://www.theguardian.com/science/the-h-word/2014/jun/02/caliche-great-war-first-world-war-conflict-mineral

Picture 4:  World War One:  http://www.excaliburunit.org.uk/#/world-war-1/4580632440

Picture 5:  US troops returning from World War One.  http://www.ww1medals.net/WW1-US-Victory-medals.htm

Picture 6:  Amyl nitrite.  http://en.wikipedia.org/wiki/Amyl_nitrite

Bacon and the art of living 1. A letter from Denmark

April, 1891

Dear Ava, Copenhagen is an amazing city(1)!

You should be by my side and experience it yourself.  They harness the wind to generate electricity for their cities. The technological advancement and the speed with which they adapt to new inventions are remarkable (Pedersen 2010: 3)

I miss you terribly!  During the voyage my mind effortlessly wondered to you, my love!  The uncertainty became like the changing waves with the only certainty in my thoughts being you.

I did much thinking on the voyage.  I have been less certain about our quest than in the weeks before I left Cape Town. I wondered if we are completely crazy!

I would pace the deck and tell myself that the plan is simple and good. We want to cure bacon.

I have been questioning everything and reflected on the road and influences that got us to this point.

David Graaff had a huge impact on me.  He may be short but has a “big” personality.  (Simons 2000:  143)  I was 6 when I met him at their butchers shop at the Shamble (4).  and he must have been 16.  I went with my dad for his weekly meat purchase as I continued to do every week after that.

I liked Dave immediately, as much as my dad liked his uncle, Jacobus Combrinck, his boss at that point.  It was Combrinck who taught David how to be a butcher (Simons 2000: 8 – 41) (2) and the fact that they could never get bacon curing right is our future.

WP_20140720_09_37_44_Pro
A newspaper advertisement for Combrinck & Ross which appeared in 1870, the year when David joined the business. (Simons 2000: 11)

It was you and me who took him on a hike up Table Mountain when my dad suggested it.  Since that first hike up Platteklig Gorge, we must have been up with him more times than with anybody else.

It dawned on me during the voyage why he did it so often.  We were kids, looking for pocket money.  Taking foreigners and wealthy locals up on a mountain where there are no established footpaths, were fun to us.  We did what we love and got money for it.

For David it must have been a way to escape the squalor of the Shamble.  The stench and disorderliness.  Its difficult to imagine how things can get so out of hand and how the city’s slaughter area can become such a disgrace.  They are making a small fortune at their number 4 shop, but the conditions are hideous.

The sensation as you make your way up the mountain is something that is hard to explain to people who have not done it.  It is as if you ascend to another plain.  The air becomes fresh and sweet.  Even gale force winds that sometimes blow invigorates the body and mind.  The dramatic movement of the coulds.  The exquisite plant life. The intoxication beautiful shape of the rocks. As you climb, you get distance between you and the world you live in and it is as if you soar above all difficulty and stress of every day life. You forget about everything except the splendour of the surroundings you find yourself in. If it was true for us as kids, growing up in Cape Town, how much more must this have been for David Graaff!

I realised that everybody needs a Table Mountain to escape to. Who would have guessed the close friendships that developed.

Remember our hikes up Kasteelpoort to the Valley of the Red Gods.  David always went on about how he would build a reservoir for drinking water to Cape Town at the top of Kasteelpoort (Slingsby) one day.  Now that he is major, I wonder if he will build it.  (Simons 2000:  25, 26). (3) I really wish him the best!  He is a remarkable man. Jacobus Combrinck has left the business to David’s running while he pursue public office at a time when David was barely 30!

Jacobus Combrinck and my dad introduced us to David Graaff.  His uncle introduced him to being a good butcher.  We introduced him to Table Mountain.  I hope we will now show him that its possible to make good bacon in Cape Town.

The disappointment of Oscar and my first attempt to make bacon still haunts me.  The pig we slaughtered on his farm was healthy.  We cured it with the curing salt we bought in Johannesburg, the meat turned reddish/ pinkish, as it should. We smoked it.  When we ate the meat two weeks later, it was off.  Why?  I know I have asked this question all the way from Potchefstroom, back to Cape Town on the train.

Uncertainty entered my mind. Why not just leave curing bacon to the people from Calne in the UK with their extra smoked Wiltshire Cure?  I am sure this is where David and Cornelius buy the bacon they import.   Was my mom not right when she told us that Oscar and me are trying to be too clever again.

from:  http://www.mareud.com/
Port of Copenhagen, from: http://www.mareud.com/

I was glad when we arrived in Copenhagen.  New places take my mind off nagging doubt.

Denmark is much better than I expected. The people are as friendly as the people at home. I thought they would be off-ish, but they are not.

Andreas met me at the harbour. He is a very intelligent guy.  Friendly and he did not mind that I know nothing about curing bacon. When I put my bags down in my room, he immediately called me into the kitchen.  He poured us two glasses of home brewed beer.  He sat down and before I even had a sip of the beer, he bluntly asked me:  “So, you want to do what with the pork meat?” This was the last time I doubted our quest.  Since then everything has changed.

I am eternally thankful to the old Danish spice trader in Johannesburg who gave Oscar and me his name and said that if we want to learn how the English cure bacon, that I must visit his friend in Copenhagen.

From Suffolk heritage direct
From Suffolk heritage direct

Andreas is a young man and I am very much impressed with him.  After we had his home made beer, Andreas showed me a textbook from the time when he did his apprenticeship at the pork abattoir in Copenhagen.  Edward Smith from Great Britain wrote it in 1873 (Smith, Edwards. 1873).  Three years after David joined Combrinck’s butchery. (2)  He showed me the book but since it was Sunday we did not talk about bacon any more.

Instead he took me on a tour of the city. It is smaller than I expected.  Everybody knows everybody.  The way they organise their meat districts are impressive.  Sheep, cattle, pork and chicken are all handled in separate areas.  The Shamble (4) in Cape Town is a disgrace.  I am very happy that David is talking as much about cleaning this up as he is about electricity and water supply to the city.  I hope he becomes major! (3, 4) My ancestors have much to teach us about decent living.  Life is worth living well!  This includes taking care where we live.  Life must reflect what nature teach us.  It must be simple, clean and orderly.

For starters, they dont let chaos and filth prevail.  They get architects to demarcate and design buildings for specific purposes. He took me to the Meat District of Kødbyen.  Special pens have been build to hold the animals.  Not like it Cape Town where the frightened animals often break out of poorly constructed camps and rampage through the streets (Simons 2000:  11).

The next day was Monday and work started.  We got up early and I went with Andreas to work.  This has been the routine every day. In the afternoon we have the last meal at around 9:00 p.m.  After supper, Andrea’s dad  read for us (Borgen, Wilhelmine and David:  50).  He reads from different books the kind of thing that men should know while his wife and Andreas’s sisters do their sowing and needle work.  I feel it is to “humor me” that they are reading from Foods by Edward Smith, but I dont mind.  It leads to the most fascinating discussions.

I dont want to boar you with the details of what I am learning.  I know you are very interested, but I dont want my letters to you to become lectures.  I miss you too much and besides, I dont want to write Oscar about nice buildings and the how clean everything is.   This is the kind of thing you and I have complained much about in Cape Town and I think you find it interesting.

I will write in great detail to Oscar and this kids about what I am learning.  You can read the letters to the kids and when I am home, I will tell you the rest. What we are learning is both an art and a science. Curing pork, like breeding good pigs, is an art.  The farmer is not a farmer.  He is an artist, nurturing his pigs for months in exactly the right way to produce good, healthy, firm meat.  Delivering it to the market with pride.  Interestingly enough, not to the meat district.  Pork and chicken are slaughtered and sold at the old and new market areas. (Gammeltorv, Nytorv, Wikipedia)

Likewise, the deboner is an artisan.  He knows exactly how to remove the meat from the bones so that the meat are presented in a way close to how it will be sold.  This is what David has been doing since he started with at Combrinck & Co.  I now wish that I also started to work with him when I was 11.

There is the curer.  He enters the curing room early and only leaves for lunch and when the days work is done.  He specialises in salts and making sure the meat doesn’t spoil.  This is after all the point behind curing.  Changing fresh pork to cured pork that families can eat it for weeks instead of having to consume it all after slaughter as is the case with lamb, beef and chicken.

There is another artisan.  The spice specialist.  The world of aromas and flavours.  He change the taste by giving the meat different tones.  Subtle tastes that excite the senses.

These artisans work together to produce extraordinary results.  Each different step in the process being handled by a tradesman. What David Graaff and Jacobus Combrinck do with the meat in Cape Town is crude salting.  Anybody can do this.  What I am seeing here is Denmark is an art!  The results are the same as the bacon Combrinck & Co imports from Great Britain.

I am completely overwhelmed by the practical training.  Besides all of this, there is the readings every night about the science behind each process.  An application of the scientific method to the butchery trade.  Discovering the science behind each process is like a fever that took hold of Europe.The realisation that cause and effect govern.  The mechanical reasons behind everything.

Since  Friedrich Wöhler made urea in a laboratory in 1828, everything has changed.  Let me explain to you why this was an important discovery.  The owner of the butchery explained it to me yesterday. Urea is part of human urine.  It is made by our bodies.  For the first time, when Friedrich Wöhler made it himself, we realised that something that came from “life” could be produced in a laboratory.  Synthesized. Copied exactly.  (Urea, Wikipedia) Before Wöhler laboratory urea we thought that there is some kind of a vital life force creating these things.  A divine energy.

The entire Europe is struct by some kind of Gold Fever.  Not physical gold.  The gold of discovering of minerals, elements and processes.  Taking what was previously only possible for nature to produce and making it in a laboratory with chemicals, compounds, liquids and gasses.  Understanding the “how” and the “why”  (Vitalism, Wikipedia).  Everybody dream about a great discovery that will bear his or her name and bring untold riches.

The peculiar reddish/ pinkish colour of cured pork.  The fact that pork spoil so easily during the summer.  Why smoking the meat makes it possible to send the bacon on long sea voyages to South Africa, Australia and the Americas. It is this scientific aspect that I enjoy most.

I love the apprenticeship part, but in the evenings I cant wait for us to read about the science.  The chemical processes.  It is like figuring out a gigantic jigsaw puzzle. During the day, the slaughter house, the deboning hall, curing room, the spice room – for me, they change into laboratories where we perform experiments. I cant wait to start writing home about the things that I learn.

Today was a cultural festival in Copenhagen.  I missed you tremendously.  It is strange that when I was at home, I wanted nothing more than to be here.  Now that I am here, despite all that I learn, I would love nothing more than to be at home.  Hold you tight at night and hiking our beloved mountains on the week-ends and after work.  Smelling your coffee on the anthracite stove in the mornings.  Taking our dogs for a hike.  Helping the kids with their homework and visiting David and his brother. I miss you so much that tears come in my eyes when I see the sun setting over the sea and I think of you, my beloved!

Tell the kids that I love them!  I will write them next.  I promise. Please send word to Oscar that you heard from me.  I cant wait to be back soon! David Graaff will know that we can make good bacon when I get back.  I am convinced of this.

Lots of love from Denmark,

Your Beloved!

Bacon and the art of living Home Page

Borgen, Wilhelmine and David, The Life and Times of David Borgen, A Citizen of Copenhagen, Dedicated to the memory of Kirsten Sivertsen nee Borgen. http://itu.dk/people/jovt/TheLifeandTimesofDavidBorgen.pdf

Pedersen, Jorgen Lindgaard.  2010.   SCIENCE, ENGINEERING AND PEOPLE WITH A MISSION, Danish Wind Energy in Context 1891-2010.  Technical University of Denmark.

Simons, Phillida Brooke. 2000. Ice Cold In Africa. Fernwood Press Slingsby Map, Table Mountain XI Smith, Edwards. 1873.  Foods.  Henry S King and Co.

http://en.wikipedia.org/wiki/Gammeltorv

http://en.wikipedia.org/wiki/Kødbyen

http://en.wikipedia.org/wiki/Nytorv

http://en.wikipedia.org/wiki/Urea

http://en.wikipedia.org/wiki/Vitalism

Notes:

(1)  Eben and Chris arrived in Copenhagen on Sunday, 9 October 2011.  It was the first destination on an extensive European and UK trip to investigate bacon production methods, ingredients and equipment.

(2)  Jacobus Combrinck took David Graaff, a small dutch speaking boy, from his home in Franschoek at age 11, to come and live with him in Cape Town and to join him in working in his pork butchery.   Combrinck visited the Graaff family in 1870.  He was a distant relative.  He was looking for someone to whom he could teach his trade and was impressed by David.  David’s own family fell on hard times and the arrangement was practical for  everybody. (Simons 2000: 8, 9)

(3)  David Graaff became major of Cape Town at age 31 in 1890.  He was responsible for building a new drainage system for the city, the construction of a reservoir at the summit of Table Mountain, excavating a tunnel crying pipes to the city and the introduction of electricity to the city with the construction of the first power station in 1892. (Simons 2000: 25, 26)

(4)  A quote from Ice Cold in Africa, p 12 about the Shamble:  “Cape Town’s slaughterhouses took their name from the original Shambles at Smithfield Market which was situated outside London’s northwest walls.  In the twelfth century, Smithfield had been the fashionable scene of jousts and tournaments but, over the centuries, it deteriorated into one of public executions and witch-burnings.

By mid-nineteenth century, the district had become a filthy and stinking slum, a sink of vice inhabited by criminals.  It was only in 1868, after the opening of London’s new Central Market at Deptford, that the slaughterhouses moved to more salubrious premises which consisted of 162 shops under a vaulted ceiling covering over three acres.

It was to the refrigeration section, added in the 1880’s, that frozen meat from overseas countries, such as Australia and South Africa, was first consigned. In general disorder and unpleasantness, Cape Town’s Shambles must have resembled those at Smithfield.  Writing in 1894, the journalist, Richard William Murray, gave a vivid description of them as he remembered them half a century earlier.  ‘Slaughtering shambles were attached to the butchers’ sales stores,’ he wrote, ‘ and the drainage from the shambles – blood and offal – coursed along the margin of the Bay, and a good deal of it was left in a state of putrefaction, and on hot days the smell was nauseating to every living thing but blue-bottle flies who regaled themselves without stint and who buzzed away in delight as musically as the drone of the doodlesack.’   (Simons 2000: 12)