Poultry MDM: Notes on Composition and Functionality
by Eben van Tonder
5 July 2020
The mechanical deboning of meat has its origins from the late 1940s in Japan when it was applied to the bones of filleted fish. In the late 1950s, the mechanical recovery of poultry meat from necks, backs and other bones with attached flesh started. (EFSA, 2013) A newspaper report from the Ithaca Journal, Wed, 30 Dec 1964 is the earliest reference I can find on Mechanically Deboned Meat (MDM) in America. It reports on research done at Cornell State College of Agriculture in an article entitled, “New Egg Package, Chicken Products Are Among 1964 Research Results.” It reports that “mechanically deboned chicken meat was put to use for the first time, and improvements were in new types of harvesting machines.”
It claims that MDM based products would be available from 1964. “Late in 1964 Cornwell researchers began preparing experimental chicken products from this meat, which resembles finely ground hamburger.” It said that the new chunky type chicken bologna, was introduced in three forms: Chicken Chunk Roll, which is half chunk meat, and Chicken Chunkalona, which is 25 per cent chunks and 75 per cent emulsion.”
By 1969, several American universities were working on these products, including the University of Wisconsin.
By the early 19870s, the removal of beef and pork from irregularly shaped bones was introduced. Originally, the aim of MDM was to reduce the rate of repetitive strain injury (RSI) of workers caused by short cyclic boning work in cutting rooms of meat operations. A press was developed to accommodate this. The success of the approach resulted in a rapid acceptance of the principles and an incorporation of the technology across Europe and the USA.
As is the case with meat processing technology in general, despite recent developments of the process, the basic approach is still the same as the first machines that was built. Initially primitive presses derived from other types of industries were used to separate the meat from the bones, using pressures of up to 200 bar. A fine textured meat paste was the end-product, suitable for use in cooked sausages. Gradual technological improvements and pre-selection of the different types of flesh bearing bones pressed at much lower pressure (up to 20 bar) produced a coarse texture of higher quality meat that could no longer be distinguished from traditional minced meat (so called 3 mm or Baader meat).
Today, a wide variety of different products are available on the market from many different suppliers of every imaginable animal protein source. Legislation differs widely between different countries on the definition of MDM. Different countries name and classify it differently and the astute entrepreneur will find opportunities in studying every aspect of this fascinating industry closely, especially in the maize of ever evolving legislation related to it around the world. As one country restricts its use on one front, other countries will be able to buy a particular grade or type at better rates and this will in turn open up opportunities in the buying-country’s market for new ways to use raw material which becomes available for it due to a drop in the price. My own foray into this world took place during a year when Woody’s gave me the opportunity to spend almost a year working with companies in England. The project I worked on was high injection pork. During this time there were changes to legislation related to ground pork. I witnessed UK prices plummet on a commodity which, in retrospect, we should have pounced on, but I knew far too little about the sausage market to exploit the opportunity. In retrospect, I knew far too little about anything related to meat, but that is a story for a different time and many of my friends who gave me a chance to work with them and to learn will smile at this! My business partner in the company we founded and where neither of us are involved in any longer will certainly have a good chuckle!
Between 10 May and 8 June 2012, at the Tulip plant in Bristol, England, we extended ground pork with 60% brine which was designed by Andreas Østergaard. Brine was tumbled into the meat, heat set, chilled, frozen and sliced. Evaluating the texture of the final product now, almost 8 years later to the day, I realise that we should have used it to create a fine emulsion for a sausage or loaves. Looking at the result of the 60% extension below, we could easily have targeted 100% or even higher. What could we have landed the raw material at in SA if we created a fine emulsion base, extended 100% or 150% with rind emulsion added and used it as the basis for a number of fine emulsion based products at our factory in Kraaifontein, Cape Town? Evaluating what we did in Bristol, the heat setting, even in our course loaf-like product, was inadequate for proper gelation, which is clearly seen in the photos below.
The lesson for me is that in order to exploit these realities, one must grasp the functional value of the raw material, which in our consideration here is MDM, but must most certainly include other similar products not necessarily classified as MDM, MRM or MSM such as ground meat or something similar. This will lead to an appreciation of the differences between various grades of MDM and related products, which will allow processors to develop new products and increase its bottom line / reduce selling prices of others as new MDM products become available and countries adjust its legislation to regulate its use. It all begins by understanding the basic principles at work in this immense and fascinating world. We begin by looking at the basics of poultry MDM.
Poultry MDM Stability
Poultry MDM has been shown to have more constant composition compared with pork, veal and beef MDM. Considerable variations in fat and protein content occur in poultry MDM. The amount of back, wing, neck, rack, skin (or no skin) or the ratio of starting material used and type of deboning machine and settings play a major part in final product composition. Deboner head pressure was increased x 3 to increase the yield from 45 to 82%; fat content significantly reduced and moisture content increased. This is an interesting observation. (Hudson, 1994)
Rancidity problems stem from the method of production. Air with increased iron because of bone marrow are the major reasons. Additional fat stems from bone marrow and skin. Phospholipid fraction, as a percentage of total lipid content, is only at about 1 – 2% in poultry MRM. Over 60% of this may be unsaturated, oleic, linoleic, arachidonic acid. These acids decrease in concentration during freezing or frozen storage of turkey meats or nuggets made from chicken MDM. This (the decrease in polyunsaturated fatty acids) may be explained by reports that chicken muscle homogenates to contain enzymes capable of oxidizing both linoleic and arachidonic acids and one was found to be stable during frozen storage, being 15-lipoxygenase. (Hudson, 1994)
Iron in MDM acts as a catalyst in lipid oxidation is well known, but -> is it haem or non heam iron that plays the dominant role in poultry? Lee et al. say that haem protein, (50% of total iron) is the dominant catalyst for lipid oxidation in poultry MDM. Igene et al. claim that “warmed over flavour” of cooked chicken meat (whole muscle) is due to non-haem iron release during heating, which is the catalyst for oxidation. Kanner et al. say that one reason why haem protein effects lipid oxidation only after heating was that catalase activity was inhibited and this allowed H2O2-activated mayoglobin to initiate peroxidation. Related to uncooked meat, these authors report an iron-redox cycle initiated peroxidation and the soluble fraction of turkey muscle contained reducing substances which stimulated the reaction. Free iron in white and red meats of chicken and turkey increases in concentration with storage time and is capable of catalyzing lipid oxidation. (Hudson, 1994)
Decker and Schanus used gel formation to separate an extract of chicken leg muscle into three protein fractions. One catalysed over 92% of the observed total linoleate oxidation. Iron-exchange chromatography of this active fraction revealed three proteins capable of oxidising linoleate. Haemoglobin was responsible for 30% of total oxidation while two components (according to Soret absorbance) were non-heam proteins and responsible for 60%. (Hudson, 1994)
Much work in this area remains.
Modification of Poultry MDM
The paste-like nature of poultry MDM limits its use. Early investigations focused on ways to “texturise” it. This can be done by adding plant protein or by various heat treatments. Sensory properties are not always what is desired. (Hudson, 1994)
One method of producing MDM products is to use a twin-screw extrusion cooker. (Extrusion Cooking) has shown – treatment of poultry MDM alone gives unsatisfactory results. The fat content of the material is too high. Satisfactory products similar to meat loaf or luncheon meat were achieved if, as binding or gelling agents, cereal flours, corn starch, egg white concentrate or soy protein isolate were combined with the MDM. This begs the question as to the gelling temperature of these products. (Hudson, 1994)
Alvarez et al. found that chicken extruded with 10 or 15% corn starch, lipid oxidation decreased as extrusion temperature rose from 71 to 115.5 deg C. They suggest that antioxidants were produced with increasing temperature. Hsieh et al. reported that a mixture of turkey MDM (40 parts) and corn flour (60 parts) increased in susceptibility to lipid oxidation above 110°C. The antioxidant BHA (butylated hydroxyanisole) was added to the raw materials before extrusion. (Hudson, 1994)
-> Haem Removal
Haem pigments in the product impacts on product stability and in poultry MDM it has a tendency to create a dark colour in the final products. Much effort is expended to remove these pigments and so extend the range of products in which the MDM may be used. (Hudson, 1994)
Froning and Johnson showed that centrifuging poultry MRM would remove haem pigments. Washing procedures was first developed in Japan to remove haem proteins, enzymes and fats from fish during the production of the myofibrillar protein concentrate, surimi. A lot of work has been done to extend the same procedure to washing MDM. However, there are several reasons why surimi technology might not be applied directly to poultry MRM, viz:
1. Surimi is prepared from whole muscle while poultry MDM is isolated from bones after most muscle tissue is removed.
2. Poultry MDM can have considerable quantities of connective tissue in the final product, e.g. histochemical investigations have shown the connective tissue: muscle ratio of chicken MRM to be 1 : 1.2.
3. Fish mince is frequently washed during preparation, but water washing is not an efficient means of removing haem pigments from MRM.
4. Lee suggested the size of perforations in the deboner drum of fish deboners ranges from 1 to 5 mm, with orifices of 3 to 4 mm giving the best quality and yield of surimi. Poultry deboners seem to have a pore size below 1 mm and thus the particle size of the products will differ. Since the term ‘surimi’ has long been associated with the product isolated from fish muscle, it is perhaps debatable as to whether the term should be applied to the material prepared from poultry MRM.
Other terms used are:
‘washed mechanically deboned chicken meat’ , ‘myofibrillar protein isolate’, (MPI), ‘isolate of myofibrillar protein, (IMP). The acronym IMP is problematic since it is widely accepted as an abbreviation for inosine monophosphate. Clearly some rationalization of nomenclature is required and perhaps a term such as ‘poultry myofibrillar protein extract’ would be more appropriate. (Hudson, 1994)
One of the earliest studies of poultry, turkey neck MDM, considered to be the darkest poultry MDM, was washed either three times in water or once in 0.04 M phosphate at various pH values, followed by two water washes. Then, the mixtures were pressed through cheesecloth to remove as much moisture as possible. The yield of paste from water-washed MRM was higher than that which had been treated with phosphate, but it had a darker colour. The researchers concluded that washing with 0.04 M phosphate at pH 8.0 provided the most efficient means of removing red pigment from turkey MRM. Froning and Niemann reported that extraction of chicken MRM with 0.1 M NaCI significantly reduced fat concentration and colour, and increased protein concentration. Others, using different washing techniques, particularly the use of bicarbonate as the washing medium, have found that either the protein content of the washed material was similar to that of the starting material, or was up to 7% lower. However, all agreed that washing drastically reduced the fat level of the recovered material. (Hudson, 1994)
Washing with bicarbonate appears to be the most efficient way of removing pigment from poultry MDM, probably due to the fact that the pH value of the slurry makes the blood proteins more soluble, there may be other factors at work to influence the final colour of the washed product. For example, Trziszka et al. found that if, following bicarbonate extraction, water washing was carried out at pH 5.5, the product was lighter than at pH 6.0, while the variable amounts of connective tissue present in the washed residue can influence the appearance of the material, as shown by Kijowski et al., who found that removal of connective tissue by sieving increased both the darkness and redness of water-washed chicken MRM. (Hudson, 1994)
The yield after washing range was 13.5 to over 62% of the starting material. Reasons for this variety may be the result of a number of factors such as source material for MRM, grinding of MRM before washing, nature of washing medium, washing time, adjustment of pH, number of washes, ratio of MDM to extractant and centrifugal force applied during separation of ‘meat’ and extractant. (Hudson, 1994)
Cryoprotectants, such as mixtures of sugars and/or phosphates, must be added for the washed material to retain its gelling and water-holding abilities during frozen storage. Washing improved the functional properties of the material – after cooking the washed MDM was more chewy, less cohesive and had increased stress values but the cooking losses from washed material were higher, probably due to the fact that ‘free’ water was absorbed during washing. The best indication of the success of the washing procedure is probably in practical terms measured by the performance of the myofibrillar complex in products. There have been a few studies who looked at this. Frozen-thawed, bicarbonate washed turkey MDM at a level of 10% reduced the fat level of frankfurters, while increasing the expressible moisture content and resistance to shear compared with control frankfurters. Scanning electron microscopy did not reveal any obvious structural differences between controls and frankfurters containing 10% washed MDM. Hernandez et al. reported – the protein paste from washed turkey MDM could be incorporated into patties at levels up to 20% without adversely affecting sensory quality. Trziszka et al. reported that up to 50% of the ground chicken meat in hamburgers could be replaced by carbonate-washed turkey MRM without reducing the acceptability of the product. A sensory panel gave slightly lower flavour scores to hamburgers containing the protein extract, although whether this was due to the ‘soapy’ taste reported by Dawson et al. is not clear. (Hudson, 1994)
-> Improving Emulsification and Gelation
Although the protein complex isolated from washed MRM could be of use in altering textural properties of poultry products, further possibilities of effecting such changes exist. For instance, Smith and Brekke found that limited acid proteolysis improved the emulsifying capacity of actomyosin isolated from fowl MDM, as well as improving the quality of heat-set gels. Kurth used a model system to demonstrate the crosslinking of myosin and casein by a Ca-dependent acyltransfer reaction catalysed by transglutaminase (EC 220.127.116.11; R-glutaminyl peptide amine gamma-glutamyl transferase). Application of the technique to actomyosin prepared from turkey MDM showed that actin did not polymerize, but that the disappearance of myosin monomer was accompanied by a concomitant increase in polymer content and that the gel strength of enzyme-treated protein was greater. The polymerization could occur at temperatures as low as 4°C, thus opening up possibilities for the manufacture of new products. (Hudson, 1994)
This is a work-in progress. As I expand the functional value of different MDM or related products, I will add it to this document. It is an adventure in discovery!
EFSA Panel on Biological Hazards (BIOHAZ). 2013. Scientific Opinion on the public health risks related to mechanically separated meat (MSM) derived from poultry and swine; European Food Safety Authority (EFSA), Parma, Italy; EFSA Journal 2013;11(3) : 3137.
Notes on Proteins used in Fine Emulsion Sausages
by Eben van Tonder
24 May 2020
I am interested in understanding the ability of gel formation of different meat proteins, their water holding capacity and the relative protein content of various ingredients used in making fine emulsion sausages. This is important, especially in South Africa where there is a heavy reliance on MDM/ MRD in emulation sausages. What can be added to increase its water holding capacity and firmness and can a pure but economical sausage be produced?
Different Meat Related Classes of Products
In making sense of this approach, it is beneficial to understand that we deal with three classes of meat-related products. I call it the pure, the deceptive and the dishonest, thus revealing my personal bias. Pure Meat products which, in my use of the term, means products where every ingredient except the spices come from an animal carcass.
Meat Analogues are starches and soyas, grains and cereals which are made so that it tastes like meat, but contains no part of an animal carcass. This is the dishonest or hypocritical class of products. Why would a vegan, for example, who does not want to eat meat, buy a product disguised as meat, but which, in reality, contains no meat? Pure meat and meat analogues are therefore two opposing and extreme ends of the spectrum.
Meat Hybrids is the middle of the two and combines meat and plant-based protein, essentially for the purpose of achieving a cheaper product. I call it deceptive because the consumer is most often misled as to the real nature of the products they buy (I say this, despite the label declaration, which is often still enigmatic to consumers). They think it’s meat, but it contains a percentage of non-meat fillers. This is almost always done to reduce the price of the product, which, in a country like South Africa, is not necessarily a bad thing. Affordable food, where “affordable” is relative to the income level of the consumer, is a very important consideration. It must also be stated that for the most part, large producers of this kind of products do not add as fillers and extenders, anything except high quality, acceptable and healthy products such as soya in the meat to extend it.
My personal preference for pure meat products is mainly based on taste and, to a lesser extent, on matters such as allergy which relate to health in that some of the fillers may be allergens. Taste of pure meat products can, in my personal opinion, not be matched in taste, firmness, mouth feel, or any other organoleptic characteristics (the aspects of the end-product that create an individual experience via the senses—including taste, sight and smell).
I am therefore interested here to learn more about the functional value of various animal proteins and fats and fillers and extenders, customarily used in producing fine emulsion sausages.
The Cost of Protein
In evaluating the options for a producer, one must first understand the real cost of protein. In the table below, you can see the relative cost per kg of protein sources, expressed in South African Rand. The buying prices per kg obviously change and you can use the following spreadsheet to recalculate it with the current prices. More importantly than the cost of the protein source is the inclusion ratio of protein in the different sources and the real cost of the protein.
So, taking the prices above, skin was, at the time of writing, the cheapest protein source, followed by soy TVP, then soy isolates, followed by offal and then chicken MDM. For knack, you need collagen.
Starch is an interesting ingredient. Tapioca Starch contains 6.67% protein (66.7g per kg) (eatthismuch) At the writing of this article, it is R12.00 per kg, which is R179,91 per kg of protein making it more expensive than MDM, but at an inclusion rate of around 4%, and with soya isolate at R39.00 per kg
The convention in SA became to use the cheapest protein source available, which is normally seen as MDM/ MRM. Add soy for better binding and pork rind, made of collagen protein, for even greater binding and gel formation. (Mapanda et al., 2015) In reality, it is done to make the products cheaper for the consumer.
The Extremities of Formulating a Sausage
There are at least three sets of characteristics normally taken into account when formulating a sausage.
-> Total Meat Equivalent (TME)
In South Africa, the minimum Total Meat Equivalent (TME) for different classes of meat products is laid down in legislation. Let’s review briefly the important equations which will be applied to the table of possible ingredients with protein percentages above.
The Dutch chemist Gerard Mulder (1802–1880) had published a paper in a Dutch journal in 1838 and this was reprinted in 1839 in the Journal für praktische Chemie. Mulder had examined a series of nitrogen-rich organic compounds, including fibrin, egg albumin, gluten, etc., and had concluded that they all contained a basic nitrogenous component (~16%) to which he gave the name of “protein” (Munro and Allison, 1964) from a Greek term implying that it was the primary material of the animal kingdom.
The term protein was coined by Jöns Jacob Berzelius, and suggested it to Mulder, who was the first one to use it in a published article. (Bulletin des Sciences Physiques et Naturelles en Néerlande (1838); Hartley, Harold (1951) “Ueber die Zusammensetzung einiger thierischen Substanzen” 1839). Berzelius suggested the word to Mulder in a letter from Stockholm on 10 July 1838. (Vickery, H, B, 1950)
Total protein % can therefore be derived from an analysis of the nitrogen content of a meat product. The following equation is used and is derived from the fact that proteins contain around 16% nitrogen.
% N by analysis x 6.25 = % Protein (since 100/16 = 6.25)
An example is if nitrogen, by analysis, is 1.85%, then the % protein is 1.85 x 6.25 = 11.5% (protein).
The protein content in lean meat is also known to be around 21%. The factor to convert protein % to lean meat is therefore 100/21 = 4.8 if we take the lean meat as 100% and divide it by 21. So, in our example, 11.5% x 4.8 = 52.2% lean meat. The equation is:
% Protein x 4.8 = % lean
We can combine these two factors to give us a way to go from % nitrogen directly to the lean meat %. 6.25 x 4.8 = 30 and % N x 30 = % lean.
A good summary of the thinking early in the late 1800s and early 1900s on the subject exists in the South African Food, Drugs and Disinfectants Act No. 13 of 1929 (See note 1). As an important historical document, it sets out the determination of total meat content. It essentially remained unchanged (apart from minor updates).
The calculations of total meat content are defined in subparagraph 4 (iv) which reads as follows: “In all cases where it is necessary to calculate total meat under regulations 14 (1), (2), (3) and (4), the formula used shall be:—
Percentage Lean Meat = (Percentage Protein Nitrogen × 30 ). Percentage Total Meat = (Percentage Lean Meat + Percentage Fat).”
-> Water Holding Capacity (WHC)
Non-meat binders are often added to meat. Such binders and extenders commonly include flour, starch, breadcrumb, cereal binders, TVP and rusk. Often these are used to hold and bind large amounts of water to reduce product cost.
There are legal limits that must be adhered to in terms of protein content for a sausage to be called a meat sausage. When fillers and extenders are used such as these, it is, however, not a pure meat product, and hybrids are created which contains both plant and animal components.
Here there is a major misconception. All animal proteins have the ability to form gels and to hold water. The functional ability of various animal proteins to do this, however, differs significantly. A thorough knowledge of these abilities of various components of the carcass is required to determine which proteins will be best to achieve what result in any particular sausage formulation.
My suspicion is that these differences were discovered as soups and meat stews were developed by early humans, which was probably motivated by the desire to soften various parts of the carcass for consumption. There is evidence that a centre of these developments emerged on the Russian Steppe. It is interesting that Russia also became the world leader in fine emulsion meat technology and the creation of hybrid meat products.
-> Taste and Texture
Taste and texture differ considerably between pure meat products and hybrids, which leads to my personal preference of the former. The meat industry employs spices as one of the major resources of making hybrid products more “acceptable”.
Animal Protein and Gel Formation
There are three functional characteristics of meat, important to our study, namely gelation, emulsification and water holding ability. It relates to meat particle binding and adhesion ability. Processed foods are the result of the combination of several protein functionalities. In mathematics we will represent it with a polynomial function. An example of this is a Russian sausage with its firm texture and juiciness which is the result of a composite protein network system which in turn is created by protein-protein interaction (gelation), protein-fat interaction or fat encapsulation (emulsification) and protein-water interaction (water binding). Even a slight change in ingredient composition and processing conditions are enough to alter the final texture materially. (Yada, 2004)
Yada (2004) summarises the functional properties of muscle proteins as follows:
Yada (2004) defines gelation as “viscoelastic entity comprised of strands or chains cross-linked into a continuous network structure capable of immobilizing a large amount of water. The process of forming a gel, i.e. gelation, occurs in muscle foods as a result of unfolding and subsequent association of extracted proteins, usually in the presence of salt and sometimes also phosphates. The rate of structural change, i.e. denaturation, is critically important. A slow unfolding process, which typically occurs with a mild heating condition, allows polypeptides to align in an ordered manner into a cohesive structured network capable of holding both indigenous and extraneous water.” (Yada, 2004) When producing boneless hams, the gel formed at the junction of the meat chunks is responsible for the adhesion and is responsible for the integrity of the product.
Cheapest Meat Product: Structure and Characteristics
The key ingredient used in South Africa in producing fine emulsion sausages is MDM/ MRM. It is the cheapest meat product, most often used as the basis for meat hybrids. (see MDM – Not all are created equal!) MDM is a source of meat protein which is “complete, containing all the nine essential amino acids.” (Mapanda et al., 2015) MDM is, however, mostly compromised due to the way it is manufactured. It also contains the least amount of protein on our table of proteins containing raw materials listed above.
The proteins and fibres are denatured / damaged to such anextent that even the protein that it contains is retarded in terms of its ability to form a gel and hold water. Non-meat extenders, fillers and emulsifiers are, therefore, often used to compensate for this. Such plant products often include soy isolate and soy concentrate. Animal products are also often used such as milk powder, whey powder and egg white. Pork skinor rind emulations provide firmness. Fillers are usually carbohydrate materials such as carrageenan and various starch materials (Mapanda et al., 2015) depending on the price point that the formulator is targeting. Low cost sausages can contain as much as 15% such fillers and extenders.
In the Mapanda study, polony was considered as an emulation type sausage. “Polony is formed by changing coarse heterogeneous meat into a homogeneous meat mass consisting of dispersed water, fat and protein, which during heating is transformed into a gel. Polony is regarded as a fully cooked emulsified sausage product” (Mapanda et al., 2015).
Skins or skin emulsions are added to provide firmness and knack, but soya and starch are customarily added to reduce the cost. Inspired by trends from Russia, there has been a trend from around 1946 (following World War 2) in the USA to employ various serials and starches in meat processing as a way to extend the meat. As such, soy protein has been commonly used. Large manufacturers of soy products aggressively targeted the meat industry to continue the use of soy as a meat extender. Spice companies became the preferred method of distribution and large amounts of money was spent on developing recipes that would include soy and starch. The industry preached that this inclusion was “beneficial” from an economic perspective and is healthy. They proclaim that soy is a good “replacer of meat due to its essential amino acids, whose composition (though slightly lower in quantity) is no different from that of meat.” Functionally, they pointed to the fact that soy functions as a binder of fine emulsion type sausages such as polony where it contributes to the water holding capacity and the emulsification of fat in the gel. The real benefit is that it’s cheaper and easier to work than meat, and by itself, this argument is without question a valid one.
POLONY: An Example of a Meat Hybrid
Let’s now look in greater detail at how different fillers, emulsifiers and extenders are used along with MDM to create a low cost meat hybrid. We follow work done by Mapanda, et al. (2015) where they investigated “varying quantities of chicken mechanically recovered meat (MRM), soy flour (S) and pork rind (R)” were used to manufacture South African polony. For the full article, see Effect of Pork Rind and Soy Protein on Polony Sensory Attributes.
Preparation of Meat
In the Mapanda study (2015) the meat components were prepared as follows.
Rind Emulation: “Pork rind is quite tough in texture. To soften it, it was precooked before use. 7.5 kg of rind was cooked in 7.5 kg (litres) of water. The cooking time varied from 4 to 5 h for the three batches of pork rind prepared. After cooking, the pork rind and water mixture was re-weighed and water added to make up the 15 kg before chopping the mixture in the bowl cutter until a fine, sticky homogenous mass called rind emulsion was formed. The rind emulsion was then allowed to cool to room temperature prior to weighing and vacuum packaging. The rind emulsion was subsequently stored at -18°C until chemically analysed or used in polony processing.” (Mapanda et al., 2015)
MDM/ MRM: “The only preparation done on the frozen MRM involved cutting it into smaller blocks for the purpose of easily fitting into the bowl cutter. The cut blocks of MRM were vacuum sealed and frozen until polony processing commenced.” (Mapanda et al., 2015)
Sausage Formulation and Analysis
In the Mapanda study (2015) the meat components were blended as follows with the following functionals added, resulting in the analysis as given.
“All nine treatments were formulated to contain 10% protein (equivalent to 48% LME). MRM, soy flour and pork rind all vary in quantities to maintain a 10% protein in the respective treatments. The percentage of water added also varied to maintain a constant product weight, while the percentage of additives was kept constant. Additives added were 8% tapioca starch, 1.8% salt, 0.016% nitrite, 0.3% phosphate, 0.05% ascorbic acid, 0.02% erythrosine dye, 0.1% each for black pepper and cayenne pepper, 0.03% ginger, 0.2% garlic, and 0.05% each for nutmeg and coriander. Each polony sample was designed to weigh 1.5 kg. Since 10 polony units were produced for each treatment, the total mixture of polony emulsion (meat and all ingredients added for emulsification in a bowl cutter) was 15 kg. ” (Mapanda et al., 2015)
“Order of adding the ingredients was the same, i.e. ingredients were added when the bowl cutter was running at low speed. After that, the speed was increased for the final chopping phase. The MRM was added and chopped first, followed by adding the salt, nitrite, the phosphate and one third of the water. This was followed by adding the rind emulsion. After that, soy flour was added into the bowl cutter and chopped for 2 min before adding spices and another third of the water. The tapioca starch was then added, after which the ascorbic acid and the last third of the water was added.” (Mapanda et al., 2015)
“The end temperatures after chopping the polony emulsion varied between 12°C
and 17°C.” (Mapanda et al., 2015)
“The polonies were cooked in a steam bath for about 2 h to an internal temperature
of 80°C as measured by a thermocouple. The cooked polony was then cooled in clean running water prior to storage at 4°C until chemical, instrumental and sensory analyses were done on the respective samples.” (Mapanda et al., 2015)
Effect on Colour
“The redness decreased, in the Mapanda study (2015), “with an increase in both rind and soy proteins. Chicken MRM contains red pigments of blood (myoglobin and haemoglobin). The replacement of MRM with white proteins (rind and soy) reduced the red colour of the polony treatments.” (Mapanda et al., 2015)
“The present findings for pink colour are consistent with Abiola and Adegbaju, who reported that, when pork back fat was replaced with rind levels of 0, 33, 66 and 100%, the colour of pork sausages decreased correspondingly. The negative effect of MRM replacement with rind and soy on the pink colour of polony can be counteracted by adding more dye during the emulsification stage. In South Africa, dyes such as erythrosine BS can be added to enhance the pink colour of polony up to the maximum level of 30 mg/ kg of the product, Department of Health.” (Mapanda et al., 2015)
“In the treatments where rind was added, white spots were observed. The white spots were actual pieces of rind which resulted from incomplete emulsification of the pork rind emulsion by the bowl cutter. This negative attribute could be rectified by extensive chopping of the raw batter of the treatments containing pork rind.” (Mapanda et al., 2015)
“The replacement of MRM with rind levels of up to 8% and soy levels of up to 4% increased the hardness (firmness) of the polony treatments, while treatments with 8% soy were softer at all levels of rind. Similar results were obtained for gumminess (Figure 5). These results show that good quality polony with acceptable hardness can be obtained with up to 4% soy and 8% rind. Beyond 4% of soy flour, the products become softer and sticky. According to Chambers and Bowers, hardness is the most important attribute to consumers because it determines the commercial value of the processed meat products. Approximately 60% of consumers will be willing to buy a sausage with a hardness of 47.3 N and higher (Dingstad). However, higher values for the parameter do not necessarily mean better quality. There is a cut-off point above which the texture of comminuted meat products would be unacceptable.” (Mapanda et al., 2015)
Related to cohesiveness, the Mapanda (2015) study found that “the addition of binding aids such as soy and rind improves cohesiveness, as long as too much is not used (Trock). Chin  established that the use of incremental levels of soy protein below 3% decreased the cohesiveness of low-fat meat products. The current results disagree with the findings of Chin as some of the treatments of polony in which only soy protein was used, for instance at the level of 4%, showed that cohesiveness increased. A possible explanation might be the difference in the fat content of the products used in their study and in the current study.” (Mapanda et al., 2015)
“For sensory texture, the attributes analysed were firmness, pastiness and fatty mouth feel. All treatments decreased in sensory firmness due to an increase of soy and rind proteins. For both pastiness and fatty mouth feel, the mean scores for these two texture attributes increased in all samples compared to that of the control treatment. Feiner highlighted that the replacing of lean meat with soy protein and water, as was done in the present study, affects texture and firmness because the replaced meat proteins contribute positively to the named parameters. It can clearly be seen that an increased replacement of chicken MRM with pork rind and soy flour reduced firmness and increased the sensory textural attributes of pastiness and fatty mouth feel in all the polony treatments, except for the control sample.” (Mapanda et al., 2015)
Pure Meat Products at the Same Low Cost
The question now comes up, if a pure meat product can be produced at the same low cost as is done in the Mapanda study. The Yada (2004) study and the table of various functional values of different animal proteins is the first clue.
I again present this article as a “work in progress” study, as I did with other investigations. Results will be reported on unless a proprietary benefit can be derived. Any suggestions and comments can be mailed to me at email@example.com. All results of relevant investigations will be listed below and the controlling principle will be: “Why think, if we can test?” I embark on this voyage with great excitement!
I came across this Anglo-Boer War photo of medical staff in the Bloemfontein Concentration Camp posted online by Elria Wessels. For those who are not familiar with the history, between 11 October 1899 – 31 May 1902, England fought a war against two independent Boer republics in Southern Africa to gain control of the lucrative gold and diamond fields of the Johannesburg and Kimberly areas. Unable to win the war against a determined foe, they placed the women and children in over a 100 concentration camps while they enforced a scorched earth policy and burned down the farmhouses of the Boers. This provides the background for the photo.
I was struck by the prominence of the Bovril poster in the photo, appearing very deliberate and staged. Further investigation revealed a fascinating history.
The Name: Bovril
The name, Bovril, comes from the Latin bovīnus, meaning “ox”. The inventor, Johnston, added the suffix, -vril, from a contemporary popular novel by Edward Bulwer-Lytton, The Coming Race (1870). It is a story of a superior race of people, the Vril-ya. They derived their power from an electromagnetic substance named “Vril”. Bovril is therefore great strength obtained from an ox. (Phillips, 1920) The essence of the meaning of the name is given in an advertisement in 1899 where it is claimed that it is “the vital principle of prime ox beef.” (Western Mail (Cardiff, South Glamorgan, Wales) 24 January 1899)
The Inventor: John Lawson Johnston
Johnston was born in 1839 in Roslin near Edinburgh where he was also educated. He studied dietetics. It was said that he pursued the discipline with a “thoroughness and pertinacity” with such “good purpose that, when, after the close of the Franco-German war, the French Government determined to thoroughly investigate the question of food concentration and preservation, he was chosen, as its Commissioner, to proceed to Canada, and make a thorough investigation of the subject. ” (The Isle of Man Weekly Times, 1900)
He was successful in the task given to him and “the French Government conferred on him the Fellowship of the Red Cross Society of France”. It is said that he realised the dream of Liebig to develop a beef concentrate “that should contain not only the stimulative extracts but also the nourishing fibrine and albumen of the beef.” (The Isle of Man Weekly Times, 1900)
“Returning to England he enlisted the cooperation of Lord Playfair, the friend and assistant of Liebig; Sir Edmund Franklin, Dr. Farquharson, and other leading scientists were quick to perceive the great value of Mr. Johnston’s invention. With their powerful endorsement and Mr. Johnston’s determined assiduity, Bovril soon became recognised as the embodiment of the latest scientific ideas on the subject of dietetics.” (The Isle of Man Weekly Times, 1900)
From the beginning, the invention had military applications as a prime objective and the British army became an important consumer of the new invention. The Marker: The British Army during the Anglo-Boer War and British Run Camps in South Africa. With a wide application in war theatres around the world, the South African War created a hungry market both from the perspective of supplying the British forces, including their hospitals and the concentration camps housing the Boer women and children. I am sure it would have included the many POW camps set up in Ceylon, India, Bermuda, St. Helena and in South Africa such as the Sea Point camp. It is here where our interest began because of the Bloemfontein photo of Elria Wessels.
I did some digging and found advertisements in British newspapers at that time, referencing its application in this war.
The Key Differentiator: What Makes it Different from Beef Extract
The following advertisement makes it clear what sets Bovril apart from all other beef extracts.
The Afrikaner Nation and Boers feature prominently in my story of bacon. The first and second Anglo-Boer war shaped our land and provided the motivation for setting up the bacon company. Here are photos from the time immediately before and after the second Anglo-Boer War (ABW). It allows the reader to visualise the context better. I dedicate this section to my friends who bring to life the Afrikaner, referred to as Boers, the Brits, and the black and coloured South Africans who fought in these wars and lived through these times.
Martin Plaut writes about the role of ‘black Boers’, as they refer to black people fighting for the Boer nations, and says that the role of these ‘black Boers’ is captured in this British ditty:
‘Tommy, Tommy, watch your back
There are dusky wolves in cunning Piet’s pack
Sometimes nowhere to be seen
Sometimes up and shooting clean
They’re steathy lads, stealthy and brave
In darkness they’re awake
Duck, Duck, that bullet isn’t fake.
Chris Pretoriusposted a quote about Plaatjies: “In 1932, Solomon Tshekisho (Sol) Plaatje, intellectual, journalist, linguist, politician, translator and writer, born at Doornfontein near Boshof, OFS in 1876, passed away in Soweto at the age of 56. He was (amongst others) court translator for the British during the Siege of Mafeking and diarized his experiences, which was published posthumously.”
Brandwater Basin (Where my great Grandfather surrendered to the British – ABW)
Bermuda, Hawkins Island
Children, Concentration Camps and War
Crossing the River
Genl. De Wet, Christiaan.
The newspaper article is from a 1950’s Sunday Times article. Who is the “Pieter” referred to in the article? There was a Pieter de Villiers Graaff who was known as the Cape Rebel (Kaapse Rebel). He was a cousin of Sir David de Villiers Graaff, who is featured prominently in my work on bacon. Pieter participated in 25 battles in the ABW against the English and on 24 March 1901 he was captured and sent to India as a POW where he remained for the duration of the war. I doubt if the Sunday Times article refers to him. He did, however, have a son, also named Pieter de Villiers Graaff. He was born on December 16, 1911 and passed away on July 11, 1988. He was 76.
The Diyatalawa Garrison is a common name used for collection of military bases of the Sri Lanka Army located in and around the garrison town Diyatalawa in the Uva Province. Sometimes it is referred to as the Diyatalawa Cantonment. It is one of the oldest military garrisons in Sri Lanka. It is home to the several training centers of the army, including the Sri Lanka Military Academy and has a detachment of the Gemunu Watch. The Sri Lanka Army Medical Corps maintains a base hospital in Diyatalawa. SLAF Diyatalawa is situated in close proximity.
It is not exactly known as to when Diyatalawa became a training station for troops, but available records show that it was selected around 1885, when the British Army first established a garrison at Diyatalawa. At that time training was conducted at the Imperial Camp, which is presently occupied by the Gemunu Watch troops. In 1900, the British War Office constructed a concentration camp in Diyatalawa to house Boer prisoners captured in the Second Boer War. Initially constructed to house 2500 prisoners and 1000 guards and staff, the number of prisoners increased to 5000. During World War I an internment camp for enemy aliens was set up.
Early in World War II the camp was reopened and German nationals resident in Hong Kong and Singapore, as well as many sailors, like those removed from the Asama Maru in violation of international law, were housed here. Also imprisoned were Buddhist monks of German extraction like Nyanaponika and Govinda Anagarika who had acquired British citizenship. In June 1941 most of the sailors were transferred to Canada. The section for Germans was sensibly divided in a pro- and anti-Nazi wing. There was also a section set up to house Italian POWs. After the Japanese started bombing the island, inmates were on 23 February 1942 transferred to camps on the mainland. Males usually went to Dehradun.
After independence the facilities of the British Army were taken over by the newly established Ceylon Army, and Diyatalawa became the primary training grounds for the young army with the establishment in 1950 the Army Recruit Training Depot later renamed at the Army Training Centre. Several of the army’s regiments were resided here, 1st Field Squadron, Ceylon Engineers (1951), Sri Lanka Sinha Regiment (1956), Gemunu Watch (1962).
The Royal Navy had a rest camp, HMS Uva, which was situated at Diyatalawa with recreational facilities; this was later taken over by the Royal Ceylon Navy in 1956, commissioning it as HMCYS Rangalla and established its training center there. They had to move out in 1962 and it was taken over by the Gemunu Watch.
On 14 March 2013, the Security Forces Headquarters – Central the youngest of the seven commands of the Sri Lanka Army was formed at Diyatalawa. Prior to this Diyatalawa served as an Area Headquarters.
Howick British Concentration Camp for Boer Women and Children
Indigenous Houses (Used by Boers in the ABW)
Northern Cape ABW
The Royal Irish Regiment recruited from the counties of Tipperary, Waterford, Wexford and Kilkenny. It served in South Africa with General Hart’s Irish Brigade. Around 30,000 Irishmen saw service with the British Army in South Africa.
Iain Hayter writes, “There were a number of instances where Irish fought Irish in the ABW and many poems poems were written, the Irish being so lyrical……… We are leaving dear old Dublin
The gallant famous fifth;
We’re going to the Transvaal
Where the Boers we mean to shift.
We are the sons of Erin’s Isle –
The famous Fifth Battalion
Of the Dublin Fusiliers.
Let this conflict be a warning
To all Britannia’s foes;
Not to tease her ftirious lion
As on his way he goes.
For if they do, they’ll fmd they’re wrong
And won’t get volunteers
To stand in the face of a Regiment
Like the Dublin Fusiliers
On the mountain side the battle raged, there was no stop or stay;
Mackin captured Private Burke and Ensign Michael Shea,
Fitzgerald got Fitzpatrick, Brannigan found O ’Rourke,
Firmigan took a man named Fay – and a couple of lads from Cork.
Sudden they heard McManus shout, ‘Hands up or I’ll run you through’.
He thought it was a Yorkshire ‘Tyke’ – ’twas Corporal Donaghue!
McGany took O ’Leary, O ’Brien got McNamee,
That’s how the ’English fought the Dutch’ at the Battle of Dundee.
The sun was sinking slowly, the battle rolled along;
The man that Murphy ‘handed in’, was a cousin of Maud Gonne,
Then Flanagan dropped his rifle, shook hands with Bill McGuire,
For both had carried a piece of turf to light the schooh-oom fire …
Dicey brought a lad named Welsh; Dooley got McGurk;
Gilligan turned in Fahey’s boy – for his father he used to work.
They had marched to fight the English – but Irish were all they could see –
That’s how the ‘English fought the Dutch’ at the Battle of Dundee.
Russians in the ABW
Lt. Col. Maximov ( A Russian volunteer) with Gen. Kolbe. Photo supplied by Elria Wessels.
Simons Town POW’s
St Helena, Broadbottom Camp, Deadwood Camp.
Treaty of Vereeniging, signed on 31 May 1902 (end of ABW2)
Gideon Jacobus van Tonder was born in 1864 in Uitenhage, Eastern Cape (then the Cape Colony). He passed away in 1924 in the Free State. He is buried at the Rustfontein Dam, which is located on the Modder River near Thaba ‘Nchu. He was the owner of the farm Brakfontein in that area. He also resided at 21 Hill Street, Bloemfontein. From 1894 to 1900 he was minister of Agriculture in the Orange Free State Government. Giel Venter from Fauresmith gave me this information. Giel is one of his descendants. If Gideon was still alive we would have spent many days talking about farming and animal husbandry and of course, bacon curing!
When President Steyn was out of the country or on leave, he acted as State President on numerous occasions. When the ABW broke out, he resigned from government after his son, Hansie, was killed at the battle of Magersfontein. Genl. De Wet wrote about it in his book, Three Years’ War.
De Wet wrote: “I can only remember three instances of anyone being hurt by the shells. A young burgher, while riding behind a ridge and thus quite hidden from the enemy, was hit by a bomb, and both he and his horse were blown to atoms. This youth was a son of Mr. Gideon van Tonder, a member of the Executive Council.”
I am planning a visit to Giel, as soon as it is permitted and will update this section with much more information.
Yunnan Xuanwei Ham (宣威火腿/xuān wēi huó tuǐ)
Eben van Tonder
10 May 2020
Yunnan is one of China’s premium food regions known for exquisite tastes. One of the major cities in this picturesque region is Xuanwei, where one of the world famous Chinese hams are produced, the others being Jinhua Ham from Zhejiang province and Rugao Ham from Jiangsu province. Yunnan Xuanwei Ham is known for its fragrance, appearance, and out-of-the-world taste. Through the ages, there have been many references in literature to the health benefits associated with the hams. In order to produce these hams, there are at least two ingredients without which the hams can not be produced. The first ingredient is salt.
The Industrialisation of Ham
Early references to Xuanwei hams go back to 1766. “Old chronicles recorded the Qing emperor Yong Zheng five years (the year 1727) located XuanWei (a city of YunNan province, China), so it is called XuanWei ham. (China on the Way) In 1909, Zhuo Lin’s (Deng Xiaoping’s third wife) father Pu Zai Ting, a businessman, mass-produced it for the first time. He established Xuanhe Ham Industry Company Limited. His company sent food technicians to Shanghai, Guangzhou (formerly Canton), and Japan to learn advanced food processing technology.
One example of the excellence pursued in Guangzhou relates to the cultivation of rice. Rice breeding began in China in 1906. However, by 1919, systematic and well-targeted breeding using rigorous methodologies was started at Nanjing Higher Agricultural School and Guangzhou Agricultural Specialized School. Between 1919 and 1949, 100 different rice varieties were bred and released. (Mew, et al., 2003) For a riveting look at the trade in Guangzhou, see the work by Dr. Peter C. Perdue, Professor of History, Yale University, Canton Trade.
By all accounts, Pu Zaiting was successful in creating a world famous ham (at least by probably standardising and industrialising the process). In 1915 Xuanwei ham won a Gold Medal at Panama International Fair. The ham, which, in the Qing and Ming Dynasties, was a necessary gift for friends and guests and which, during the gourmet festival, became the main ingredient to create different delicious dishes achieved international acclaim. (chinadaily.com)
The Xuanhe Canned Ham Industry Company Limited was established on the back of canning equipment bought from the United States of America to produce canned ham. Most of what it produced were exported overseas. In 1923 Sun Yat-sen tasted the ham at the National Food Exhibition held in Guangzhou. Sun famously wrote of the ham, “yin he shi de” translating as “eat well for a sound mind!” By 1934, four companies were producing the canned ham. (Kristbergsson and Oliveira, 2016)
Xuanwei Ham expanded greatly under the People’s Republic of China, established in 1949. Supporting industries started to develop. A factory was created to supply the cans used by the Municipal Authority of Kunming City. (Kristbergsson and Oliveira, 2016)
Production of Xuanwei hams rose by 1999 to 13 000 tonnes, made by 38 large producers. In 2001 it got the status of a regional brand, protected by the People’s Republic of China. A Chinese standard, GB 18357-2003 was subsequently issued. By 2004 production rose to 20,750 tonnes with technology in manufacturing and packaging improving continuously. (Kristbergsson and Oliveira, 2016)
Apart from a rich and competitive environment, an entrepreneur, as the proverb goes, worth his salt, was needed to bring discipline to the production process and to establish this ham among the finest on earth. In achieving this status, three elements were required, namely salt, the right meat and a solid production technique to yield this culinary masterpiece on an industrial scale.
Yunnan – Centre of Culinary Excellence
The first requirement for competitiveness is an environment of excellence and innovation. The environment where this exquisite ham is produced testifies to culinary excellence. Like Prague, which produced the ham press, nitrite curing and the famous Prague hams, the Yunnan hams likewise hail from an area replete with food and cooking innovations. Yunnan is located on what was known as the Southern Silk Road and its culinary excellence is seen, among other things, in the equipment used in preparing their foods. Joseph Needham, et al. reports that in restaurants in the cities of Yunnan, a very special dish is found “in which chicken, ham, meat balls and the like have been cooked in water just condensed from steam. This is done by means of an apparatus called chhi kuo (or formerly yang li kuo) made especially at Chien-shui near Kochiu. It consists simply of a red earthenware pot with a domical cover, the bottom of the pot being pierced by a tapering chimney so formed as to leave on all sides an annular trough (figure 1490). The chhi kuo once placed on a saucepan of boiling water, steam enters from below and is condensed so as to fall upon and cook the viands of the trough, resulting thus after due process in something much better than either a soup or a stew in the ordinary sense. Since the chimney tapers to a small hole at its tip no natural volatile substances are lost from the food, hence the name of the object and the purpose of its existence. The chhi kuo must claim to be regarded as a distant descendant of the Babylonian rim-pot (for it has and needs no Hellenistic side-tube) with the ancient rim expanded to form a trough, compressing the ‘still’-body to a narrow chimney. But how the idea found its way through the ages, and from Mesopotamia to Yunnan, might admit of a wide conjecture.” (Needham, et al.,1980)
The second essential ingredient for a salt-cured ham is salt. Salt is something that China has been specialising in for thousands of years and which became the backbone of the creation of this legend.
Salt in China
Flad, et al. (2005) showed that salt production was taking place in China on an industrial scale as early as the first millennium BCE at Zhongba. “Zhongba is located in the Zhong Xian County, Chongqing Municipality, approximately 200 km down-river along the Yangzi from Chongqing City in central China. Researchers concluded that “the homogeneity of the ceramic assemblage” found at this site “suggests that salt production may already have been significant in this area throughout the second millennium B.C..” Significantly, “the Zhongba data represent the oldest confirmed example of pottery-based salt production yet found in China.” (Flad, et al.; 2005)
Salt-cured Chinese hams have been in production since the Tang Dynasty (618-907AD). First records appeared in the book Supplement toChinese Materia Medica by Tang Dynasty doctor Chen Zangqi, who claimed ham from Jinhua was the best. Pork legs were commonly salted by soldiers in Jinhua to take on long journeys during wartime, and it was imperial scholar Zong Ze who introduced it to Song Dynasty Emperor Gaozong. Gaozong was so enamored with the ham’s intense flavour and red colour he named it huo tui, or ‘fire leg’. (SBS) An earlier record of ham than Jinhua-ham is Anfu ham from the Qin dynasty (221 to 206 BCE).
In the middle ages, Marco Polo is said to have encountered salt curing of hams in China on his presumed 13th-century trip. Impressed with the culture and customs he saw on his travels, he claims that he returned to Venice with Chinese porcelain, paper money, spices, and silks to introduce to his home country. He claims that it was from his time in Jinhua, a city in eastern Zheijiang province, where he found salt-cured ham. Whether one can accept these claims from Marco Polo is, however, a different question.
Salt Production In and Around Yunnan
When it comes to salt, only a very particular variety is called on to create this legend.
Around the Yunnan-Guizhou plateau are three salt producing areas which took advantage of the expansion of China towards the west in the early modern era. “Szechwan with a slow but steady advance; Yunnan with the speed and initiative characteristic of a developing mining area; Mongolia with a sudden, temporary eruption.” (Adshead, 1988) As fascinating as Szechwan and Mongolia are, we leave this for a future consideration and hone in on Yunnan.
Szechwan not only supplied its own requirements for salt, but also that of Kweichow, Yunnan (trade started in 1726) and western Hupei. Despite the fact that Yunnan imported salt from Szechwan and possibly from Kwangtung, this was mainly to supply its eastern regions of the escarpment. On the plateau it had salt resources of its own. By 1800, it is estimated that it produced 375 000 cwt (hundredweight).”These salines formed three groups: Pei-ching in the west near Tali the old indigenous capital; the Mo-hei-ching or Shihi-koa ching in the south near Szemao close to Laotian and Burmese borders; Hei-ching in the east near the provincial capital Kunming. (Adshead, 1988) It is this last group that captures our imagination due to the connection with the Yunnan hams.
Although known as ching or wells, many of the Yunnan salines, especially those in the Mo-hei-ching group, were in the nature of shafts or mines, though the low grade rock salt was generally turned into brine and evaporated over wood fires. The growth of the Yunnan salines in the Ch’ing period was the product of two forces. First, Chinese mining enterprise, often Chinese Muslim enterprise, which in the 18th century was turning Yunnan into China’s major source of base materials – copper, tin and zinc. Second, the extension of direct Chinese rule into the area, the so-called kai-t’u kuei-liu, initiated particularly by the Machu governor-general O-er-t’ai between 1725 and 1732. (Adshead, 1988)
The distant past of Heijin comes to us, courtesy of Yunnan Adventure Travel, who writes that “the unearthed relics of stones, potteries, and bronze wares have proved that as early as 3,200 years ago, ancestors of some minority groups already worked and multiplied on this land. It’s recorded in the “Annals of Heijin” that, a local farmer lost his cattle when grazing on the mountain, he finally found his black cattle near a well; but to his surprise, when it lipped the soil around the well, salt appeared; thus in order to memorize the black well, the place was nicknamed as “Heiniu Yanjin” which means the black cattle and the salt well. It’s shortly referred to as Heijin afterwards.” (www.yunnanadventure.com) Some accounts of the story have it that it was a Yi girl who was looking for her missing oxen when she came upon them licking salt from the black well.
Who better to take us on a tour of the old town than a seasoned traveller! We meet such a wanderer in the old city of Heijin in the person of Christy Huang. She takes us on an epic adventure, discovering the old salt kingdom of Hei-ching. She posted it on Monday, November 30th, 2015 and she called her post “Old Towns of Yunnan, Heijing.”
Christy writes that “the quite fameless Old Town of Heijing (黑井古镇) – today one of the nicest in Yunnan – used to be famous for the high-quality salt which was produced there since hundreds of years. The once most important town of Yunnan is hidden at the banks of Longchuan River in Lufeng County of Chuxiong Prefecture of Yunnan.
Salt production in bigger scale began in the Tang Dynasty (618-907) and peaked during the Ming (1368–1644) and Qing (1644–1912) Dynasties. Besides the overall beautiful picture of Hejing and its surroundings, there are a couple of scenic spots worth mentioning:
Courtyard of Family Wu,
Ancient Salt Workshop,
Dalong Shrine, as well as,
Heiniu Salt Well.
The Courtyard of Family Wu used to be the residence of former salt tycoon of Heijing Old Town. The mansion was built during 21 years in mid 19th century and is formed in the shape of the Chinese character wang (王), which means king. It has 108 rooms, which have been left more or less unchanged. Today it serves as an (expensive) hotel for Heijing visitors.
The Ancient Salt Workshop was Heijing’s core place and fortune fountain. The remaining huge water wheels and stages for making salt testify the great prosperity of the bygone times. The salt produced in Heijing is as white as snow. It was and is used for preserving Yunnan’s well-known Xuanwei Ham.” (Christy Huang, 2015)
The third ingredient in the production of Yunnan Xuanwei Ham is the pigs. Traditionally, the rear legs of the Wujin pig breed are used. The breed is known for its high-fat content, muscle quality and thin skin (chinadaily.com).
The breed is usually kept outdoors and is typical in the Xuanwei region. They are normally fed on corn flour, soybean, horse bean, potato, carrot, and buckwheat. They are slow growers, but their meat is of superb quality.
They write that “there is a quiet little revolution taking place by the banks of Nujiang River, the “angry river”, the upper stretch of the famous Mekong as it passes the narrow gorges near Lijiang. Here, little black pigs wander freely by steep meadows, grazing on wild herbs and foraging as freely as wild animals. They are relatively small, compared to their bigger cousins bred in farms. These sturdy little animals are reared for about two to three years before they are slaughtered and made into the region’s organic hams – called black hams for their deep-colored crusts.” (Yingqing and Anfei)
Li Yingqing and Guo Anfei report on “Wang Yingwen, a 47-year-old farmer who has raised the black pigs for more than 30 years, says the pigs are fed spring water and they live on wild fruits, mushrooms and ants on mountains, an all-organic diet if there was one. (Yingqing and Anfei)
With increased industrialisation came the demand for a faster growing animal. Wujin pigs were being crossed with Duroc (USA), Landrace (Denmark), and York (UK) to achieve faster growth. Wujin x Duroc were crossbred. Other crossbreeds are York x (Wujin x Duroc) and DLY (Duroc x (Landrace x York). Yang and Lu (1987) found that the cross itself does not materially influence the quality of the ham as long as the breed contains 25% Wujin blood. (Kristbergsson and Oliveira, 2016)
In Xuanwei City, pig production is big business! In 2004, the city loaned 120 million yuan to breeders. By this date, the city had 31 breeding facilities each yielding 3000 pigs annually. There were an additional 9600 small breeding facilities. 356 Animal hospitals support the breeding and husbandry operations. In Xuanwei City, 1.2 million pigs were sold in that year. (Kristbergsson and Oliveira, 2016)
Consumers want a great product (consistency, despite volumes offered by industrialised processes) and a great story (focussing on the ancient history of the process and ham itself). Work to accomplish this was funded by the Yunnan Scientific Department, the Yunnan Education Department and Xuanwei City Local Government who all promoted the continued development of the Yunnan Xuanwei Ham (宣威火腿/xuān wēi huó tuǐ). (Kristbergsson and Oliveira, 2016) Modern processing methods moved away from seasonal production and embraced modern processing technology, but the great legends of the past remain as well as tailor-made production techniques catering for year-round production.
Processing Yunnan Xuanwei Ham
The Xuanwei climate explains the production methods used, as is the case with all the great hams around the world. Xuanwei City is located on a low-latitude plateau mansoon climatic area where the north sub-torrid zone, the southern temperature zone, and the mid-temperature zone coexist. Winter lasts from November to January and spring occurs from February to April. February, March, April is sunny and clear and this leads to a low relative humidity during these months. From March to September it is overcast and rainy, and the relative humidity is comparatively high. Winter is the best time to salt the hams according to the old methods to limit microactivity till salt dehydrates the meat and reduces the water activity. The rainy season is best for fermenting the ham. (Kristbergsson and Oliveira, 2016)
As in all meat processing, making the hams start with good meat selection. The process starts in the winter. The animal is killed and all the blood pressed out by hand. Animals are between 90 and 130 kg (live weight) when slaughtered.
A simple flow chart is given by Kristbergsson and Oliveira (2016).
Slaughtering and Trimming
Traditionally Xuanwei people kill the pigs usually before the last frost. They add boiling water to a wok and scrape the pig’s hair. Some people refer to killing the pig as washing the pig. For villagers, the killing of the pig is a sacred ceremony. (China on the Way)
The hind leg is trimmed into an oval shape in the form of a Chinese musical instrument, the pipa. The legs of small pigs are cut in the form of a leaf. The legs cut off along the last lumbar vertebra. After the blood is pressed out, the meat is held for ripening in a cold room at a temperature of 4 to 8 deg C, relative humidity of 75% for 24 hours. Ripened legs are known as green hams. (Kristbergsson and Oliveira, 2016) This step is an enigma to me since I am not sure what is accomplished in such a short period of time. My guess is that it is not technically ripening, but rather allowing any excess fluids to drain out. I will keep interrogating the processing steps to ensure that my sources have the right information.
The green hams are then salted. The salt is a mixture of table salt (25g/kg of leg) and sodium nitrite (0.1g/kg leg). (Kristbergsson and Oliveira, 2016) The inclusion of sodium nitrite is without question a modern development since nitrite curing of meat only became popular after World War I. My instinct tells me that they originally only used salt and later, possibly, sodium nitrate, the production of which has been done for very long in Chinese history.
The salt is rubbed into the hams by hand massaging for around 5 minutes. “The salted hams are then stacked in pallets and held in a cold room at 4 to 8 deg C, 75 to 85% relative humidity for 2 days. Salting procedure is then repeated.” The salt ratios are this time changed to table salt of 30g/kg ham and sodium nitrite is kept at 0.1g/kg leg. The meat is rested for a further 3 days in the chiller after which another salting is done. The ratio of this salting is 15g of table salt per kg of ham and again, sodium nitrite is kept at 0.1g per kg ham. (Kristbergsson and Oliveira, 2016)
According to Li Yingqing and Guo Anfei, “traditionally made hams are cured with half the salt used in factories. Instead, they are allowed to dry-cure for at least eight months to about three years, so the meat has time to mellow and mature.” “The longer the ham is cured, the better the quality and the most popular product now is the three-year-old cured ham.”
The hams are then hung in the drying room with a temperature of 10 to 15 deg C and relative humidity of between 50 and 60%. (Kristbergsson and Oliveira, 2016) Note how the temperature is increased and the relative humidity decreases to facilitate drying from the inside, out.
The excess salt is brushed away and the hams are dried for 40 days. Windows are kept open to facilitate air movement to air drying. Screens are placed in front of openings to prevent flies, other insects and birds from entering. If drying is too fast, a crust will form on the outside of the ham and if it is done too quick, the inside will not be dried and will spoil. If drying is done too long, the meat will be too dry to accommodate the lactic acid bacteria which will be involved in the fermentation process.
Li Yingqing and Guo Anfei reports on the traditional way that drying was done. “If you visit the villages by Nujiang, you may chance upon a strange sight in winter, when the hams are hoisted high on trees so they can catch the best of the drying winds. These trees with hocks of ham hanging from them seem to bear strange fruit indeed.”
After drying, the temperature is raised to 25 deg C. Relative humidity is pushed up to 70% and ideal conditions are created for fermentation. This process lasts for 180 days. Apart from creating an ideal condition for microbes, raising the temperature and humidity favours enzymatic activity, which is important in flavour development due to the partial decomposition of lipids (fat) and proteins. (Kristbergsson and Oliveira, 2016)
“Xuanwei ham is like good wine: the older the better. A ham that’s been aged at least 3 years can be eaten raw like prosciutto di parma.”
Control of Pests
During the curing and drying stages, flies pose a major risk. During fermentation and storage ham moths and mites (eg. tyrophagus putrescentiae) are the major danger. Relative humidity of over 80% attracts flies such as Piophila casei,Dermestes carnivorus beetle and mites. “There has been considerable work done in controlling mite infestation. Microorganisms such as the Streptomyces strain s-368 help prevent and treat mite investigation.” (Kristbergsson and Oliveira, 2016)
Storage is done under ambient conditions and the hams can be stored between 2 and 3 years.
“The physical and chemical properties of dry-cured ham are important determinants of its quality (Jiang et al. 1990 ; Careri et al. 1993 ). The lean portion of Xuanwei ham contains 30.4 % protein, 10.9 % fat, 10.3 % amino acids, 42.2 % moisture, and 8.8 % salt (Jiang et al. 1990 ). The whole ham contains 17.6 % protein, 29.1 % fat, 5.6 % amino acids, 24.8 % moisture, and 3.3 % salt (Jiang et al. 1990 ). Many essential elements are present in the ham as are some vitamins. The ham is particularly rich in vitamin E (45 mg/100 g). The characteristic bright red color of Xuanwei ham is mainly attributed to oxymyoglobin and myoglobin. The flavor and taste are associated with the presence of various amino acids and volatile organic compounds . The volatile substances present in Xuanwei ham have been extensively studied (Qiao and Ma 2004 ; Yao et al. 2004 ). Seventy-five compounds were tentatively identified in the volatile fraction. The compounds identified included hydrocarbons, alcohols, aldehydes, ketones, organic acids, esters, and other unspecified compounds.” (Kristbergsson and Oliveira, 2016)
The dominant microorganism on the surface of dry cured hams is mold, which affects quality. During the ripening stage, molds play an important and positive role in flavour and appearance. A study of Iberian dry-cured hams showed that yeasts are predominant during the end of the maturing phase of production whereas Staphylococcus and Micrococcus are absent. This surface yeast population has been shown to be useful for estimating the progress of maturation. Its contribution to curing is suggested to be their proteolytic or lipolytic activity. (Kristbergsson and Oliveira, 2016)
In Xuanwei hams, researchers have shown Streptomyces bacteria to dominate and account for almost half of the Actinomycetes. Aspergilli and Penicillia are common on the surface of Xuanwei hams during June to August. They found 8 species of Aspergillus. A. fumigatus was found to be dominant and accounts for one third of Aspergilli. Generally speaking, a high relative humidity encourages mold development on the surface of the hams. (Kristbergsson and Oliveira, 2016)
The dominant fungi found on Xuanwei hams is yeast. Yeast can be 50% of the total microorganisms found on mature dry-cured hams. Proteolytic and lipolytic activity of yeast is desirable. Towards the end of maturation, yeast dominates on dry-cured hams. (Kristbergsson and Oliveira, 2016)
Which species to be found during the different stages of production depends on temperature and relative humidity. In the Xuanwei region, humidity and temperature are highest during the rainy season. Molds occur almost exclusively on the surface of the hams. Aspergilli and Penicillia occur mostly during May when relative humidity and temperature are high. These fungi peak in July and August. Molds begin to grow in May and are well established by June. Spores are formed in August and September. The quantity of spores falls off gradually in September. (Kristbergsson and Oliveira, 2016)
“The growth of bacteria and Actinomycetes does not seem to be dependent on humidity in the curing room. Levels of bacteria are generally lower than levels of yeast. According to Wang, et al. (2006) yeast on ham multiplies exponentially from the beginning of the salting stage to reach a peak in April, and then the numbers drop and stabilise to around 2 x 107 cfu/g.Yeast levels within the ham show similar variation as the surface yeast. According to Wang et al. (2006) yeast accounts for 60 to 70% of the total microbial population on the surface of the ham. In some cases, no molds have been found growing on the surface of good-quality ham; therefore, some researchers believe that molds do not play a direct role in determining the quality of dry-cured ham, but an opposing view also prevails.” (Kristbergsson and Oliveira, 2016)
“According to the traditional view, high quality Xuanwei ham must have “green growth” (i.e. molds) on it. However, fungi such as Penicillia , Fusarium , and Aspergilli are known to produce mycotoxin in foods such as dry-cured Iberian ham (Núñez et al. 1996 ; Cvetnić and Pepeljnjak 1997 ; Brera et al. 1998 ; Erdogan et al. 2003 ). More than 15 % of the mold strains examined were found to produce mycotoxins in Xuanwei ham (Wang et al. 2006 ). The toxins penetrated to a depth of 0.6 cm in the ham muscle. Because most of the fungi that occur on ham have not been examined for producing mycotoxins , contamination with toxins might be more prevalent than is realized.” (Kristbergsson and Oliveira, 2016)
“The ham must be flame burned and washed before eating, in order to remove the rancid taste.” (China on the Way.)
There are an infinite variety of ways to serve the ham. It can be steamed, boiled, fried, or used as accessories. Old legs can be eaten raw. When cooking, cook either the whole ham or large cuts on a slow fire or slow boil it to retain the flavour.
Flad, R., Zhu, J., Wang, C., Chen, P., von Falkenhausen, L., Sun, Z., & Li, S. (2005). Archaeological and chemical evidence for early salt production in China. Proceedings of the National Academy of Sciences of the United States of America, 102(35), 12618–12622. http://doi.org/10.1073/pnas.0502985102
Functionality of protein sources and gelling properties;
Water Holding Capacity (which speaks to affordability);
Mouth-feel, bite and firmness / tenderness;
Freeze/ thaw stability where required;
Hot boning is a technique where practitioners claim that water holding capacity is high, without the need to use phosphates. In emulsions made from such meat there is no need for non-meat extenders, emulsifiers and stabilisers. The processing is also achieved without the need for expensive and unnecessary refrigeration. It can have a material impact on shelf life by extending it and renders the end product firmer with a better visual appearance. It is therefore worth a proper consideration.
Hot boning is when bones and fat are removed from the animal carcass within a few hours after slaughter, before chilling. Some researchers distinguish between hot and warm boning. We will get into these differences at a later stage.
A short and clear description of hot boning is given by Dr. Lynn Knipe, who is, amongst other things, responsible for the processed meats extension programs at Ohio State University and conducts research related to the quality and safety of processed meat products.
Dr. Knipe writes that “the fresh, “bloom” color of meat is enhanced with rapid chilling (using CO2) of pre-rigor meat, as soon after hot boning as possible. This improvement in color can be reflected in a sharper particle definition (less smeared look), as well as a leaner appearance. While there are other functional advantages to hot boning of meat, currently, the main commercial reason for pre-rigor boning of pork is to extend the shelf life (time until the lean loses color) of the fresh color. Other advantages to pre-rigor processing include a firmer texture to the final cooked sausage, with less cooking loss.” (Knipe)
Schematically, the difference between hot-boning and cold-boning is represented as follows:
A German friend who is a 3rd generation Master Butcher tells me that his dad never used emulsifiers or stabilisers in his fine meat emulsion, and his secret was hot boning. Well, it was not really a secret – it was practiced throughout Germany.
Let’s briefly look at the ingredients normally used in sausage production. We will consider them by listing protein content and the relative price of the different proteins. This will show that when formulating products, a proper evaluation of the different ingredients is required.
In the table below I give the relative protein %’s of different functional ingredients and the Rand price as it was in April 2020. The links attached to this paragraph title and title below in the table are live and you can download the spreadsheet and insert the price of these protein sources in your own currency. You can also adjust the protein % of the particular product you use. The manufacturer must be consulted to get this information. The final protein % will depend on the particular product blend and the production method used.
If you do not know that pork loin typically contains 20.85g of protein per 100g of meat (20.85%), you can calculate it as 0.8kg of lean meat (in a 80/20 trim ratio) to get to the % lean that is 0.8 (% lean) / 4.8 = 16.7% protein. It follows from the formulas below.
-> Remember the key equations:
%N x 6.25 = % Protein
% Protein x 4.8 = % lean
6.25 x 4.8 = 30
So, %N x 30 = % lean (Mellett)
The red and blue raw materials show the difference between high and low-end products.
-> High-End and Low-End Products in South Africa
Local food legislation invariably calls for a minimum protein percentage and usually specifies what the source of the proteins must be. The hybrid meat formulations in South Africa usually contain a mixture of the ingredients listed in blue. High quality sausages or loaves or hams are produced in South Africa from either primal cuts (whole muscle) or from the ingredients listed in red. The question is if hot boning is used and all the costs are taken into account, including labour, energy (refrigeration and cooking), is it possible to come close to the price point when low-end products are produced, again, taking every input cost into account.
-> Hot Boning – A way to Make High-End Products Affordable
Hot boning is of interest for its Water Holding Capacity and its ability to form stable emulsions without the need to add non-meat fillers, stabilisers and extenders and the firmer texture and visual appeal. Due to the availability of data from the USA, it makes it easier to trace the history of the development of the technique from there.
Early work on Hot Boning in America
The Des Moines Register reported in 1974 on the work of Dr. R. L. Henrickson of the Oklahoma Agricultural Experimental Station where he had been working on hot boned meat since 1965. His initial work was on pork, and later he included beef in his research. Henrickson says that the concept was conceived by his research team in 1957. He is quoted as saying that pork from this process is “equal or better” in quality compared to conventional methods. It is interesting when he says that “we are fast approaching a time when social and economic pressures will force the implementation of new meat processing procedures.” (Des Moines Register, 1974) Such conditions have existed in many parts of the world for a long time.
Status of Hot Processing of Meat in the United States
Arguably one of the foremost authorities on hot boning, Dr. Henrickson writes that “there appears to be very little direct industry application of hot processing of primal cuts in the United States, even though most research evidence points to many advantages for the various available processing systems.” In contrast to this, “the success of the pork sausage industry can be attributed directly to the short processing period from slaughter to the chilled or frozen package. The system makes raw seasoned sausage available to the consumer in less than 90 minutes after slaughter. This process not only takes advantage of economics in processing and chilling, but provides the consumer with a sanitary, longer shelf-life product. The major bulk of the raw pork sausage industry now uses pre-rigor pork.” (Henrickson, 1983)
“The raw pork sausage industry uses young sows with the proper ratio of fat to lean. This careful selection of the animal makes it possible to blend a product without a great amount of excess fat.” If sausages are made, the following steps are followed.
-> Sausage Production
Separate the lean meat and fat from the bone;
Chopped into uniform pieces;
Cool it, partially;
Add spices / seasoning;
Stuff into one and two pound grease-proof casings.
Cool down “using an ethylene glycol bath system.
Another option is to extrude the pork sausage links with or without casing directly onto a liquid nitrogen enclosed endless belt. “By the time each link reaches the end of the belt it has absorbed sufficient refrigeration to be case frozen.”
Packaged and tempered to 0 deg F / -18 deg C for marketing.
-> If Not All the Meat is Used Immediately
Pork tissue (lean and fat) which can not all be used for sausage production immediately are handled as follows.
Salted (2-4 percent) during the following procedure of . . .
Coarse chopping of the meat
Place in 50-60 pound / 20-25kg boxes and freeze.
The pre-salted meat is used in sausage manufacture because of its ability to yield myosin for binding.
There is a variation on the above system which is commercially appealing, namely to produce the slabs of coarse chopped meat with spices and fat or rind emulsion already blended in. I have seen this widely in use in India and Nepal and my intention is to test these methods and create a product which can be exported to small scale butchers who lack the equipment or experience to create the emulsions.
Hot Boning and Some Chilling
Pre-rigor pork has been demonstrated to have many benefits. In America it is a matter of preference. Dr. Henrickson writes that “the prospect of cutting hog carcasses directly from the dressing line prior to chilling makes the average packing house worker shudder. The reason most often given is that one cannot trim hot cuts to presentable standards of appearance.”
Dr. Henrickson argues that the attitude in the US against hot-boning due to appearance is invalid “since most of the primal cuts do not require a high standard appearance value. All pork cuts except the loin and spare rib are subjected to some manner of forming either by can, package, stockinette, casing or press. Therefore, the only primal cut which may require some form of smoothness is the loin. Smoothness of the loin can even be attained by leaving the back fat intact, conveyorizing the loin through a blast chill and then trimming. A few minutes in a blast chill at -50°F / -45 deg C should provide ample firmness for the necessary trim. An alternative would be to market a completely boneless loin, since the consumer is now discriminating against fat and bone. The whole concept of hot processing not only requires converting practices of plant and market, but the thinking of personnel.” (Henrickson, 1983)
Henrickson reports that there has been progress during the past thirty years and expresses the hope that the process will be widely adapted in the future. He says that “even though the pork industry has been reluctant to adopt hot processing for primal cuts, it has reduced the period from kill to package. High volume (880 hogs per hour) ham production (kill to can in three days) has been practiced since 1965. Pickle solution is automatically injected into the meat and the cure is equalized in a matter of hours. A flexible vacuum wrapper makes the product ready for shipment and distribution in less than three days. Hot processing could reduce this time by an additional day.” (Henrickson, 1983)
There is a widely held belief that microbial problems are a major drawback to the system of hot boning. There is evidence that hot processing could provide a more sanitary products. (Henrickson, 1983)
These claims were further investigated by Fung, et al. (1981) who found that if “hot-boned meat is chilled adequately (from carcass temperature to 21 C with 9 h) during the first 24 h, the hot-boned meat is acceptable in color and odor and bacterial quality after 14 days of storage and 3 additional days of display. When meat is not chilled adequately (from carcass temperature to 21 C at 12 h), the shelf-life and storage life will not be acceptable.”
Their research showed the need for adequate chilling after boning the hot meat “at a rate sufficient to produce a bacteriologically acceptable product.” Boxing the meat before chilling is, according to their data, doable, but should be approached with great care. They caution against too-rapid cooling rates of hot-boned meat which can lead to cold-induced muscle shortening, which, in turn, causes toughening of the meat. (Fung, 1981)
They claim that faster chilling rates of up to 3-9 h after fabrication can be used as an additional insurance for better microbial quality and still the processor will be able to avoid cold-induced toughening. They also add that electrical stimulation can very successfully be used in conjunction with hot-boning, as an extra measure to prevent muscle toughening. They therefore recommend “chilling hot-boned meat to 21 C within 3-9 h after fabrication, and with continuous chilling, to below 10 C within 24 h.” (Fung, 1981)
Another way to prevent cold shortening is to select bigger carcasses with more fat. The smaller and leaner carcasses are more susceptible to cold shortening due to the reduced fat cover, which results in the deep areas chilling faster. This results in tougher products. Apart from carcass selection, this can be overcome by introducing a conditioning step (semi-hot boning) of 4 hours more until rigor has occurred (in beef it can take 24 hours or even longer). To reduce the time for rigor to occur, electric stimulation is used immediately after slaughter. It must however be reminded that in pork, cold shortening is not such a big problem because postmortem metabolism in pork occurs faster.
Generally speaking, hot boning can even double microbiological shelf life due to the fact that surface bacteria have not had time to grow before antimicrobial salts are added. Even if the meat is slightly tougher, in comminuted meats this is not a problem because a higher ultimate pH is achieved (what we achieve with phosphates in South Africa). Because of the higher pH there is an increased water holding and emulsifying capacity, which will yield a product that is juicy and of superior quality. Pre-rigor meat also acts as an oxygen-scavenger. It removes residual oxygen from inside the package after closure, resulting in a long shelf-life.
This does not mean that micro should not remain a major concern in hot or semi-hot boning. There will be an increase in moisture on cutting surfaces and great care must be exercised to prevent this becoming a vector for microbial contamination and growth.
In hot boning, it is easier to remove fat from the warm cut. Care must be taken to maintain a juicy product with flavour, brought out by the fat. It will be important to reduce fat variability rather than cause it to increase. (Fung, 1981)
Summary of Benefits of Hot Boning Compared to Cold Boning
Ockerman and Basu from Ohio State University reported the following benefits of Hot Boning compared to cold boning.
Higher meat yield (1.4%)
Labour savings (20%, faster – 4 mins / carcass) (with the right equipment to hold carcass still and pull muscles downwards)
Less weight loss during chilling (1.5% less)
Less purge in a vacuum package (0.1 – 0.6%)
More uniform products
Reduced refrigeration space (50 – 55%)
Lower refrigeration cost (40 – 50%)
Shorter processing time (40 – 50%)
Lower transport cost (primals vs carcasses)
Superior water holding capacity
Higher emulsifying capacity
(Dikeman and Devine, 2014)
Shape distortion of cuts because the bone is removed;
Reduced flexibility in production;
Stricter hygiene requirements;
Increased temperature control;
New cutting procedure;
Retrofitting of traditional cold boning area;
Retraining or hiring new cutting personnel;
Possible reduced tenderness because of cold and rigor shortening;
Alteration of colour;
Accelerated micro growth.
(Dikeman and Devine, 2014)
In the USA, hot boning is used mostly by whole-pig fresh sausage processors who use hot boning and rapid salting.
Rigor Complex Formation of Actomyosin
With the onset of rigor mortis, ATP disappears from the muscle. In the absence of ATP, actin and myosin combine to form rigor complex of actomyosin (Kamejima, et al., 1982) Willi Wurm, Master of Meat Science and Processing put it in terms that I can understand. In private communication he said that “actomyosin has to be separated again during a sausage emulsion process, by adding phosphate. Only separated Actin and Myosin have the capability to make an emulsion with fat and water. With hot boning methods you can keep the Actin and Myosin separate, when you grind the deboned meat and add salt. After that you cool or freeze the meat or process. The Actin and Myosin remain separate, and you can process without phosphate. You can also vacuum pack whole muscle pieces before the postmortem process and wet-age it. It will be classified better than normal wet-aged beef meat. Be careful to store the warm packed meat for the first night outside the fridge on tables and then refrigerate the next morning for 4 weeks.
Oscar Mayer was the first to apply hot boning to a large commercial operation. They used it to process packer sow hams to be used in sausage manufacturing. (Dikeman and Devine, 2014) The weight of these sows, which is “owned by a packing plant”, therefore packer sows, is between 110 and 140kg.
After the initial publication of this article I received fascinating comments from around the world.
Gary Hendrix from NSC BEEF PROCESSING sent me the following communication. “We do hot beef boning, breaking primals down. The good thing about this is once broken down you can cryovac for aging. Reducing your shrinkage greatly. Getting a great bloom on your product as well. Reduce fatigue to your boners, difference between cutting a hot stick of butter or cold. Greater yield, easier to clean the carcass. Faster, reduces labor. Cooling down time is faster, less chance for pathogens to grow. These are only a few advantages. We also have developed and patented the technology with which to process beef without exposing the spinal cord. A huge advantage for BSE. NO BONE MEAL AS WELL. Labor savings as much as 30-50%. We will soon be taking a 3 day industry standard of kill floor to truck down to 1 day.” For those of you who are interested, Gary can be contacted at NSCbeef@yhaoo.com, 117 Land Grant Lane Baird, Tx 79504 325-665-0602 Cell 325-518-5038.
Another person (still awaiting permission to use his name) recalled that “all the American processors were using hot boned meat, also went to a company called Marjacks who were producing a lot of further processed products, not sure if they are still going but would be a good source of information as would Wayne Poultry as they had an incredible set up for hot deboning.”
Not everybody had such a positive experience with hot boning of beef. Someone (awaiting aproval to use his name) said, “I used to do a bit back in the 80s not great for presentation or yield. Hot Beef Boning, selling vac packed into wholesale. Very fast, but poor yields and doesn’t do much for cutting quality. We soon stopped it.”
I have never been exposed to hot boning. The South African Meat Safety Act of 2000 (ACT No. 40 OF 2000) stipulates that meat must be cooled to a core temperature of 7 deg C before dispatch. Paragraph 40 (1) reads as follows. “A chiller used for chilling warm carcasses, sides, quarters or portions must be capable of providing uninterrupted cooling to reduce the core temperature of the meat to 7 def C before dispatching.” According to this definition, it seems as if hot boning can be done as long as the bond meat reaches the required 7 deg C temperature before dispatch. I will take the matter up with a meat inspector.
In Germany, hot boning was widely used. Gero Lutge, the third-generation Master Butcher I was talking about in the introduction, sent me the following account of his dad’s use of hot boning. he writes, “in the earlier years my dad went to the local abattoir on Monday morning to slaughter the amount of pigs he pre-ordered. Then he loaded it onto his bakkie (pick up) in half pigs. Had a Schnapps and a beer at the tavern on the abattoir premises and went back to his butchery to immediately brake the pigs, debone them and prepare them for the week ahead. The meat trimmed for emulsion processing was immediately processed with a lot of ice so still not cooled down. The only additive he added was curing salt and spice. Even if he filled the emulsion a day later, the water intake and binding was tremendously higher than with phosphate when the pH level of the meat decreased overnight in the chiller.”
I am sufficiently intrigued to at least test pre-rigor meat for sausage production and legally there may be a way to do it even in South Africa. The motivation will be to simplify the process by removing the need of the 2-4% addition of extenders, stabilisers and emulsifiers. I am motivated by the comparison made by Ockerman and Basu from Ohio State University between cold and hot boning where they clearly and persuasively show the economic advantages of hot boning.
There is every reason to look into this very carefully!
Dikeman, M., Devine, C.. 2014. Encyclopedia of Meat Sciences. Second Edition. Academic Press.
In 2018, I started on a journey to understand the determination of total meat content and the historical roots of the determination. Tonight I begin the last installment in this short overview. We start with some calculations again. Through experimentation, the following rations were determined.
% Lean Meat
%N x (6.25 x 4.8) = % Lean Meat. This means that,
%N x 30 = % Lean Meat
How was the 4.8 determined?
We know that Lean Meat (fat-free) contains 20.8% protein.
So, % Protein x 100/20.8 = % Lean Meat which is 4.8
Meat Protein contains 16% Nitrogen. So, %N x 100/16 = % Protein
In other words, %N x 6.25 = % Prot.
I have a major interest in fats. An old man, native to Africa, once told me his grandfather and mother told him that Africans before Europeans arrived, knew that eating too much game meat, which is very lean, will poison you. The solution which his grandfather gave was to slaughter a fat tale sheep, which the indigenous population farmed with, and mix the fat from the tale into the meat from the buck.
This intrigued me. It speaks of a sophistication in meat processing technology never before properly credited to Africa, pre-colonialisation. The second matter of interest is the statement related to the importance of fat in diet. As I searched the topic, I came across a concept called protein poisoning. I was even more interested. The question is then, in determining total meat content and limiting the fat that may be present, is there any dietary benefit we derive from fat? Apart from the energy. From Africa, I learned that having a diet devoid of fat was believed to be detrimental to one’s health, but is there a scientific basis for this belief? We start this section reviewing some basic bio chemistry and we then look at the history of the fascinating question.
When we talk about Lean Meat we exclude fat and fat is the final component in determining total meat content to consider. Here we briefly overview biochemistry of lipids as a macromolecule. In the second part, I quote Arthur A. Spector and Hee-Yong Kim’s excellent article, Discovery of essential fatty acids. I have only twice before quoted an entire article but the work they have done is so excellent that there is no need for me to try and summarise their work any further. Even if the biochemistry required to fully comprehend their review is substantial, it is written well enough that a cursory reading will open up the world of the health benefits of lipids.
Lets then begin by briefly looking at lipids as one of the macromolecules that form the ingredients of life. Other macromolecules, which form the ingredients of life are carbohydrates, proteins, nucleic acid and, of course, lipids.
Section A: A Basic Introduction to Lipids
The Formation of Macro Molecules
Lets first consider how macromolecules are formed. Macromolecules are often polymers (not always). A polymer is the repeat of a monomer and we can write it as (monomer)n or Mn. In the formation of macromolecules, there are two kinds of reactions that are important namely condensation and hydrolysis reactions. Condensation reactions form bonds and hydrolysis reactions break bonds.
Condensation Reactions: A monomer with a hydroxyl group interacts with another monomer with a hydroxyl group and the outcome is a bond between the two monomers with the release of water represented as follows: M – OH + M – OH -> M – O – M + H2O A hydrolysis reaction is exactly the opposite.
A hydrolysis reaction is exactly the opposite. The di-monomer with an ether bond between them adds water and the bond between them is broken. Both of these reactions often require energy to proceed. The particular class of macromolecules important to us is the lipids.
A lipid is a name given to a host of different biomolecules, all of which can be dissolved in nonpolar solvents. Typically this includes hydrocarbons used to dissolve other naturally occurring hydrocarbon lipid molecules that do not (or do not easily) dissolve in water. Scientists sometimes classify lipids and small hydrophobic molecules which include fatty acids, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, phospholipids, and triglycerides. Note that there are some lipids that have hydrophilic parts. Some lipids are therefore all out hydrophobic (non-polar molecules which do not like water); some lipids have hydrophobic and hydrophilic parts called amphipathic molecules. These substances fare well when we use them as emulsifiers. For a more detailed discussion about emulsifiers, have a look at Emulsifiers in Sausages.
About 5% of the dry mass of a cell consists of lipids. They are an important energy store for cells with energy-rich bonds and key to the formation of cell membranes. They are involved in signaling. They are important in insulation in terms of keeping the organism warm and also in insulating nerve cells as the nerve cells transmit their signals.
The condensation reactions during lipid formation often involve the synthesis of triglycerides.
Triglycerides are formed from glycerol to which a fatty acid is bound. A fatty acid is a hydroxyl group (hydroxyl group is denoted by –OH), bound to a carbonyl group (a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O) attached to long-chain hydrocarbons. Out of the glycerol, attached to a fatty acid comes then a triglyceride. The reaction that forms the triglyceride is a condensation reaction as well as a transesterification reaction with the formation of an ester bond. Transesterification is the process of exchanging the organic group R″ of an ester with the organic group R′ of an alcohol.
Let’s look a bit closer at esters. “Esters are an important functional group in organic chemistry, and they are generally written RCOOR’ or RCO2R’. An ester is characterized by the orientation and bonding of the atoms shown, where R and R’ are both carbon-initiated chains of varying length, also known as alkyl groups.
As usual, R and R’ are both alkyl groups or groups initiating with carbon. Esters are derivative of carboxylic acids where the hydroxyl (OH) group has been replaced by an alkoxy (O-R) group. They are commonly synthesized from the condensation of a carboxylic acid with an alcohol.”(courses.lumenlearning.com)
Lipids are not strictly speaking polymers.
Another representation of triglyceride.
Glycerides are esters formed from glycerol and fatty acids that are, as we pointed out before, are very hydrophobic. The fatty acids are long chains of carbon atoms (from 12 to 20 C atoms) with a COOH group at the bottom and have this typical zigzag structure. In organic chemistry, they are also called carboxylic acids.
Why is fat not very soluble in water? If we look at the structure of fat, can we predict if it will be hydrophobic or are there parts that will be hydrophilic? In the triglyceride I have shown above the three fatty acids are the same, but it is much more common when different fatty acids are present.
There are no obvious charges that will bind to water. Oxygen is a bit more electronegative and we will have a partial positive at the carbon. Then again, carbon is more electronegative than hydrogen. It will therefore not form the kind of hydrogen bonds that one will see if we were dealing with hydroxyl groups as would have been the case if this was an alcohol. The carbon chains are very hydrophobic which is what makes fat not soluble in water. They clump up when you add them to water.
There are a number of important triglyceride chains that are important for the food processor namely saturated fats and unsaturated fats.
– Saturated and Unsaturated Fats
In saturated fats, the triglyceride chains have all single carbon atoms with all of them completely saturated (as in, there are no double bonds). Triglycerides with these kinds of chains all pack tightly. This gives them the property of chemical stability and gives them a high melting point. Saturated fats are often solid. These are bad for humans. A saturated fat is “saturated” with hydrogen atoms. We will see in a minute that unsaturated fats have a double carbon bond somewhere in its structure and wherever a double bond occurs, a hydrogen atom is eliminated which means it is “unsaturated” in terms of hydrogen atoms.
By contrast, unsaturated fats are sometimes good for humans and sometimes not. As we said, unsaturated fats have a double carbon bond. “A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.” (sciencedaily) Where double bonds are formed, hydrogen atoms are eliminated which makes them unsaturated in terms of hydrogen atoms.
“The greater the degree of unsaturation in a fatty acid (ie, the more double bonds in the fatty acid), the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation. Foods containing unsaturated fats include avocado, nuts, and soybean, canola, and olive oils. Meat products contain both saturated and unsaturated fats. Unsaturated fats are liquid at room temperature.” (sciencedaily)
This link with rancidity of great interest to the food scientist. “Rancidity is the oxidation of fats that is caused by hydration (water), oxidation (oxygen), metallic atoms or microbes. Rancidity often produces unusual odor and/or taste.” (Marcus, 2013) “Unsaturated fatty acids are a component of the phospholipids, which we discuss next, in cell membranes and help maintain membrane fluidity.” (Pelley, 2012)
There are two kinds of unsaturated fats. CIS unsaturated fats where the other bonds that are available to the carbons are on the same side of the molecule. Remember that there is no free rotation around a double bond. This means that the molecule is stuck in its configuration. CIS fats paks poorly because they are kinked and have a low melting point and these fats are good for us.
The other kind is TRANS unsaturated fats where the additional valances of carbon are on opposite sides of the molecule. These fats are similar to saturated fats as they too pack tightly with a high melting point. These are particularly bad for us. Trans fats are seldom found in nature. They are, however, found in confectionery products.
One of the important characteristics of lipids is that they can be modified. This happens when one of the fatty acid chains are replaced with something that is polar. The triglyceride is very non-polar, consisting mainly of hydrogen and carbons. Replacing one of the fatty acid chains with something that is polar, dramatically alter the properties of the molecule. A very good example of this is the formation of a phospholipid.
A phospholipid is a great example of an amphipathic molecule (with both hydrophilic and hydrophobic parts). They are similar to triglycerides in structure. One of the fatty acid groups is replaced with a phosphate which is highly charged. On the one end, the molecule is then polar and on the other end, it is non-polar. This causes them to self-associate where the polar groups face water and the non-polar groups face one another. these will self-associate and spontaneously form a lipid bilayer. A bilayered membrane will thus be formed.
One of the fatty acids is replaced with a phosphate group. The chains from the fatty acids (hydrocarbon chains) are hydrophobic. The phosphate end has charge and charged molecules dissolve in water very well. The head is, therefore, hydrophilic with two hydrophobic tails. To qualify as a phospholipid, the phosphate group should be modified by an alcohol. This structure makes them ideal for cell membranes.
Other examples of lipids are waxes and steroids.
Another example of lipids is waxes which also exist as esters.
The reason we call it an ester is because we have an ester functional group where a carbon double bonded to oxygen and single bonded to another oxygen which in turn is bonded to a long hydrocarbon chain. The carbon is also bound to a long hydrocarbon chain. The molecule is obviously very hydrophobic. Such a structure is characteristic of one of the major constituents in Beeswax.
“Most naturally occurring fats and oils are the fatty acid esters of glycerol. Esters are typically fragrant, and those with low enough molecular weights to be volatile are commonly used as perfumes and are found in essential oils and pheromones.” (courses.lumenlearning.com)
Another very common example of lipids is steroids.
Steroids share a common ring structure. They are lipids with a common ring structure. Their precursor is cholesterol which is an essential lipid and is essential for the formation of the membrane and is crucial for signaling. The issue with cholesterol is that too much is bad.
An ester has the characteristic rings. Three are 6 carbon rings and one is 5. If it has an OH group attached to it, it actually is an alcohol and a steroid which is called a sterol.
An example of a familiar sterol is cholesterol. Cholesterol is essential for life. It is a precursor molecule for steroid hormones, for example, testosterone.
Let us briefly return to our discussion on trans fats. Cholesterol is used for membranes and in signalling but is carried through the body by a component called low-density lipoprotein is deposited in the arteries where it clogs up and caused heart attacks. If the cholesterol binds to high-density lipoproteins (a different kind of a transport molecule) then excess cholesterol is secreted by the liver with no adverse effect. Transfats and saturated fats increase the levels of low-density lipoprotein and therefore increases the risk of a heart attack. 80% of cholesterol is produced by our bodies and 20% comes from our food which is why eating a low cholesterol diet does not usually help if you have high cholesterol. One must interfere with its synthesis which is what drugs like statins do.
Another example of lipids is Vitamin D which is important in the prevention of inflammation.
Section B: History of the Recognition of the Role of Lipids in Nutrition
The History of Understanding the Nutritional value of Lipids
As is customary in our blog, we now place some of the concepts we have learned about in the first part of this article in a historical context. A hundred years ago, a key question under consideration was if fat is important in our diet. “In 1929, a young, comparatively unknown assistant professor of plant physiology at the University of Minnesota, George Oswald Burr, reported that the deficiency disease observed in rats fed a fat-free diet was caused by the absence of dietary fatty acids, not by the lack of a lipoid contained in the fat, and he concluded that fat was an essential dietary component. Burr then demonstrated that the addition of a small amount of linoleic acid, the 18-carbon ω-6 polyunsaturated fatty acid containing two double bonds (18:2ω-6), cured this deficiency disease and, therefore, was an essential fatty acid. These two seminal papers are now regarded as classics in biochemistry, but they initially met with considerable skepticism. To understand why one must appreciate the paradigm-changing nature of the discovery and the stature of the experts whose views concerning dietary fat were being challenged by Burr’s findings.” (Spector, 2015)
Views on the Role of Dietary Fat in the Early 20th Century
Proteins and carbohydrates were known to be indispensable dietary components by the first decade of the 20th century. However, dietary fat was not considered to be essential because fatty acids were known to be synthesized from carbohydrates. The evidence concerning fat was not definitive due to the inability to completely extract fat from the other dietary components using the methods available in the early 1900s, and the experimental fat-free diets of that era contained traces of residual fat.
Two of the most prominent physiological chemists of the early 20th century, Thomas B. Osborne of the Connecticut Agricultural Experiment Station and Lafayette B. Mendel of the Sheffield Scientific School at Yale University, began their studies on the role of dietary fat in 1912. Osborne and Mendel were working collaboratively in New Haven and were already recognized world-wide for their pioneering studies on dietary proteins. Their initial findings indicated that rats gained weight normally when fed a fat-free food mixture, and they concluded that “true fats” are not required for growth. However, Osborne and Mendel were aware of the work of Wilhelm Stepp in Strasbourg, who found that a lipoid present in egg yolk was an essential nutrient for mice. MacArthur and Luckett at the University of Illinois also reported that a lipoid extracted from egg yolk was necessary for optimum growth of mice.
Osborne and Mendel realized that the fat-free diet used in their studies may have contained an essential lipoid because it had not been extracted with hot alcohol. They explored this issue and in 1913 found that the growth of rats actually was reduced by a fat-free diet but was restored when an ether-extract of protein-free milk was added to the food mixture. The necessary factor was shown to be present in milk fat, butter fat, egg yolk, and cod liver oil, and extremely small quantities of this “accessory substance” supported growth. Although Osborne and Mendel determined that the substance was not an amine, they suggested that it was similar to the vital amines, then called “vitamines”, that were known to be essential dietary components. Elmer McCollum, who had done a year of postdoctoral study with Osborne and Mendel, but by this time was working independently at the University of Wisconsin, also reported that an ether-soluble substance contained in egg or butter fat restored the growth of rats consuming a fat-extracted diet. He concluded that the growth-promoting effect was due to an indispensible organic complex “in the nature of lipins”, or some substance accompanying lipins, which is an “essential accessory article in foodstuffs”. The substance discovered by Osborne and Mendel, and independently by McCollum, was initially called the “growth-promoting fat-soluble vitamin” and was subsequently designated as vitamin A. Both groups reported that the failure of the rats to grow was not due to the absence of dietary fat, lecithin, or cholesterol, findings that diverted attention away from the possibility that fatty acids might be essential nutrients.
The question of the essentiality of dietary fat was rekindled between 1918 and 1920 by Hans Aron in Breslau, who reported that fats had a specific nutrient value that could not be replaced by other foodstuffs and was not accounted for by caloric value alone. Osborne and Mendel argued that these findings were not convincing because they were obtained with butter, which contained other vital nutrients besides fat. Because of the uncertainty raised by Aron’s findings and the confusion between lack of fats and deficiency of fat-soluble vitamins, Osborne and Mendel decided to reexamine the question of whether “true fat” was an essential dietary component.
Dietary Fat Studies in the Early 1920s
Osborne and Mendel fed young rats diets exceedingly low in true fats, which they defined as compounds soluble in ether. The diets contained adequate amounts of fat-soluble vitamins from dried alfalfa and water soluble vitamins from dried yeast. To reduce the fat content as much as possible, the dried meat present in the food mixture was extracted five times with ether containing alcohol. The rats fed this lipid-extracted diet grew as well as those fed diets with liberal portions of butter fat or lard, and Osborne and Mendel concluded: “If true fats are essential for nutrition during growth the minimum necessary must be exceedingly small.”
While this statement equivocates to some degree, the research community of the 1920s interpreted it as a definitive statement that dietary fat was not essential. Negative results also were reported in 1921 by Jack C. Drummond in London. Drummond fed young rats a diet lacking neutral fat from weaning to maturity and found that they developed normally and exhibited normal behavior. He concluded that neutral fats are not required in the diet provided that the vitamins associated with fat are supplied adequately, and he stated that the real value of fat is that it is a convenient source of energy. Based on the findings of these leading experts, there was general agreement that true fats, that is, glycerides and their fatty acid moieties, were not essential nutrients.
These results and conclusions of Osborne and Mendel, and of Drummond, had a powerful influence on nutritional science in the 1920s. George Burr explained why at the Golden Jubilee International Congress on Essential Fatty Acids and Prostaglandins in 1980. The Congress, organized by Ralph Holman, was held to honor Burr for the discovery of essential fatty acids, and also Ulf von Euler for his part in the discovery of prostaglandins (PGs). In remarks delivered at the Congress banquet, Burr said that: “We had been told on high authority that fats per se were not required in the diet, and our minds were closed.”
Considering the stature of the individuals who concluded that fat was not an essential nutrient, it is easy to understand why Burr considered this as coming from high authority.
Thomas B. Osborne was internationally renowned for his work on dietary proteins and was one of the most prominent American biochemists of the early 20th century. He was a member of the National Academy of Sciences and an Honorary Fellow of the Chemical Society (London). Osborne served as the fourth President of the American Society of Biological Chemists, was awarded a gold medal by the Paris Exposition of 1900, and received an honorary degree from Yale University. Osborne’s collaborator, Lafayette B. Mendel, was an equally prominent leader of American biochemistry and a founder of the science of nutrition.
Mendel was head of the Department of Physiological Chemistry at the Sheffield Scientific School. This renowned department was founded by Russell H. Chittenden, considered the dean of American biochemistry, and it was the first scientific department devoted specifically to biochemical studies in the United States. Mendel also was the Sterling Professor of Physiological Chemistry at Yale University, was elected to the National Academy of Sciences, served as the fifth President of the American Society of Biological Chemists and the first President of the American Institute of Nutrition, and received honorary degrees from Michigan, Rutgers, and Western Reserve Universities. Jack C. Drummond was a well-recognized nutritional biochemist who had a large laboratory in London in the 1920s. Drummond was appointed the first Professor of Biochemistry at University College London in 1922, became Dean of the Faculty of Medical Science, and was subsequently elected a Fellow of the Royal Society. A young, relatively unknown investigator had to be mature, self-confident, and willing to take chances to challenge such high authority, and George Burr was such an individual.
George Oswald Burr
Burr was born in 1896 in Conway, Arkansas, played cornet in the Conway Juvenile Band, and harvested wheat in Kansas during summer vacations. He received a BA degree from Hendrix College in 1916, where he was a member of the football team. Burr had a variety of experiences between 1916 and the end of 1918. He was Principal of a high school in Crossett, Arkansas, Professor of Science at Kentucky Wesleyan College, attended summer school at the University of Chicago, worked for General Electric in Erie, Pennsylvania, and served in the United States Army Signal Corps.
In 1919, Burr was appointed Chief Chemist of the Arkansas Feed and Fertilizer Inspectors. He resigned shortly thereafter and formed the Little Rock Oil Company to drill for oil, but the company disbanded after hitting a dry well. Burr then obtained a MS degree in chemistry and mathematics at the University of Arkansas and began working for the Missouri Pacific Railroad. He resigned in 1920 after winning a scholarship to the University of Illinois to work on the synthesis of organic arsenicals. In 1921, Burr accepted a job as a science teacher at the Wichita, Kansas high school, but resigned when he was awarded a Fellowship from the Department of Biochemistry at the University of Minnesota to join the laboratory of Professor Ross Gortner. While a graduate student, Burr again showed his entrepreneurial spirit by opening a mill in Wells, Minnesota to produce sugar from corn. Burr also worked for two summers on plant distribution in the Utah and Arizona deserts with Professor J. Arthur Harris, head of the Department of Botany at the University of Minnesota. Although this summer job was unrelated to his thesis project, Burr’s association with Professor Harris had a pivotal influence on his future career. In 1924 at the age of 28, Burr received a PhD in Biochemistry and Chemistry from the University of Minnesota. His thesis characterized condensation products formed during protein hydrolysis called humins.
Burr’s experiences were much more extensive and varied than the average newly minted PhD. He had taught in public schools, studied at four universities, worked in industry and State government, did fieldwork on plants, and had military service. His moves to new locations and ventures in drilling for oil and milling corn indicate a degree of self-confidence and willingness to take chances. These traits would serve him well in his subsequent research studies.
Postdoctoral studies at the University of California, Berkeley
Burr was awarded a National Research Council Fellowship to work with Herbert M. Evans at the University of California, and he headed for Berkeley after receiving his PhD degree. Evans was an anatomist and physiologist who, with Katherine Scott Bishop, had recently discovered a dietary factor essential for reproduction, subsequently called vitamin E. Evans, who directed a large well-funded laboratory, needed a biochemist to isolate and characterize the anti-sterility factor that he and Bishop had discovered, and Burr had the necessary expertise. Burr progressively purified vitamin E from wheat germ, first isolating it to the oil extract and then to the nonsteroid fraction of the nonsaponifiable lipids. Burr stated that by chance the Evans group was having trouble with reproducibility of their vitamin E experiments which they attributed to the presence of variable amounts of lipid containing vitamin E in the basal diet used to produce the sterile female rats for testing.
To investigate this possibility, Burr set up a separate colony of rats that were fed a fat-free diet that he prepared, consisting of sucrose recrystallized from alcohol, purified and reprecipitated casein, salts, and vitamin supplements. The rats fed this diet developed a disease that was different from vitamin E deficiency. Evans and Burr reported this new dietary deficiency, initially only emphasizing the potential usefulness of the experimental diet without speculating on the cause of the deficiency. Burr’s further work demonstrated that, unlike the known fat-soluble vitamins that were present in the nonsaponifiable lipid fraction, the substance which prevented the disease was present in the fatty acid fraction of the lipid extract. Based on this finding, Evans and Burr hypothesized that the active factor was a new vitamin-like substance present in the fatty acid fraction of fat and tentatively designated it as vitamin F.
Burr, in his written comments in 1980, stated: “Over a period of 4 years of work and 3 published papers, it never occurred to us that the deficiency was the lack of a well-known fatty acid.”
A personal event occurred during Burr’s tenure in Berkeley that turned out to be an important factor in his subsequent discovery of essential fatty acids. Burr married Mildred Lawson, an assistant in the Evans laboratory who was in charge of the rat colony. Mildred’s expertise with laboratory rats was vital for Burr’s subsequent studies on fatty acid deficiency, and she was the coauthor of the two classic papers on the discovery of essential fatty acids. Mildred Burr was also a coauthor of the 1932 paper reporting the essentiality of α-linolenic acid (18:3ω-3), the ω-3 analog of linoleic acid that is the parent of the ω-3 family of polyunsaturated fatty acids
Faculty appointment at the University of Minnesota
The University of Minnesota completed a new Botany Building with adequate space in 1926, and Professor Harris, with whom Burr had worked during summers on plant distribution in the desert, was given new positions to expand the Botany faculty. Harris recognized Burr’s talent and succeeded in recruiting him as an Assistant Professor of Plant Physiology. Burr left for Minneapolis in September, 1928, stating: “With deep sorrow and high hopes, the Burr’s left Berkeley in their Model T Ford roadster with two cages of Long-Evans rats…. On cold fall nights, our pets were smuggled into hotel rooms under long overcoats.”
Although Professor Harris hired Burr as a plant physiologist, he told Burr that he didn’t care what type of research he did as long as it was good work. Burr decided to continue his fat nutrition studies, so Harris arranged space for a rat colony in the attic of the Anatomy Building. The attic room was equipped with air conditioning and the finest individual metabolic cages, and Burr set up a small rat colony with the cooperation of C. M. Jackson, Professor of Anatomy. Burr received support from the University of Minnesota Research Fund and a grant from the Graduate College, but funding still was very limited. He states that because of the shortage of research funds, Mildred Burr pitched in and made some of the special observations, including the effects of the fat-free diet on the estrus cycle and fertility. Thus, the paradigm-changing studies on essential fatty acids had their beginning, and the resulting papers were published with Mildred Burr as coauthor
The classic papers of 1929 and 1930
Burr realized that to make further progress, he had to rigidly exclude fat from the diet and describe the new deficiency symptoms in quantitative terms so that the relative curative value of additives could be measured. The paper published in the May 1929 issue of the Journal of Biological Chemistry describes the purification of the fat-free diet in great detail and contains a much more complete description of the deficiency disease than the prior Evans and Burr publications. The results proved that dietary fat was required to stimulate growth and prevent disease in rats fed the fat-free diet. The key finding, shown in Fig. 2 which is reprinted from Burr’s 1929 paper, was that the component of the fat that stimulated growth and prevented disease was the fatty acid fraction, not the nonsaponifiable lipids or the glycerol backbone of the glycerides. Burr concluded that, “The data presented here definitely settle the uncertainty as to the necessity for fats in the diet (of the rat) and prove not only that ingested fats have a beneficial effect upon the animal but that under certain experimental conditions outlined in this paper they are essential constituents of the diet.”
The second paper, published in 1930, describes additional abnormalities that occurred in the rats fed a fat-free diet, including effects on water exchange and ovulation, and investigates the nature of the essential fatty acid. Because the preparation of pure unsaturated fatty acids was problematic at that time due to isomerization of the double bonds, the studies were done primarily with oils containing different combinations of fatty acids, and also with fatty acid esters. Burr found that oils containing linoleic acid and methyl linoleate were effective, and he stated that: “We were driven to the conclusion that the only thing that could be missing from the diet was linoleic acid. So, in March or April 1930, we wrote a paper announcing linoleic acid as an essential fatty acid, and that term was born.”
Figure 3 contains key data reprinted from the 1930 paper demonstrating the essentiality of linoleic acid. It shows that lipids containing linoleic acid, especially linseed oil, corn oil, and poppy seed oil that have a high content of linoleic acid, as well as methyl linoleate, stimulated growth and prevented essential fatty acid deficiency in rats fed the fat-free basal diet. Egg lecithin, butter fat, and olive oil, which contain lesser amounts of linoleate, were somewhat effective, whereas coconut oil, which is highly saturated, and methyl stearate were ineffective. While these results indicated that methyl oleate also stimulated growth, this finding was not confirmed in Burr’s subsequent studies.
Two additional important insights arecontained in the 1930 paper. Burr reasoned that because the quantity of dietary linoleic acid required to prevent the deficiency disease was very small, linoleic acid is not synthesized by animals. Furthermore, he stated that in addition to linoleic acid, some of the more highly unsaturated fatty acids present in phospholipids are also probably essential. This was largely ignored, and the commonly held interpretation was that linoleic acid is “the” essential fatty acid.
The Controversy and Its Resolution
Ralph Holman states that the subject of the essentiality of polyunsaturated fatty acids was born into controversy because the finding was too revolutionary for many. He quotes Burr as saying: “In my opinion the most striking aspect about the discovery of EFA [essential fatty acids] was the complete surprise with which it struck the nutrition researchers. The belief was deeply rooted that, except as carriers of fat-soluble vitamins, fats were merely a concentrated source of calories easily stored in plants and animals.”
Herbert Evans, Burr’s postdoctoral mentor, who by then had been elected to the National Academy of Sciences and was internationally recognized for the discovery of vitamin E, wrote a letter of condolence chiding Burr for having stuck his neck out and made such an error. Burr states that this criticism was especially disturbing because he was well aware of the difficulties in that era of establishing the purity of unsaturated fatty acids. Ironically, a paper from the Lafayette Mendel’s laboratory describing the effects of a fat-free diet on the growth of rats was also published in the May 1929 issue of the Journal of Biological Chemistry. Mendel’s group observed that rats fed a fat-free diet grew poorly and exhibited the same symptoms as described by Burr. They found that the best growth occurred in the rats that received a small amount of fat in the diet, and they stated that their findings strengthened the argument that dietary fat may have a beneficial effect. However, in contrast with Burr’s definitive statement, their overall conclusion was equivocal: “Whether this apparent beneficial effect of a small amount of fat is due to its content of vitamin A or other vitamins, or to its action as a vehicle for the fat soluble vitamins, or whether fat per se is essential, is not conclusively demonstrated.”
This paper is often discussed in a context that implies that the Mendel group challenged Burr’s conclusion regarding the essentiality of fatty acid. However, the two papers were received by the Journal of Biological Chemistry 8 days apart in February 1929 and were published in May, and there is no evidence of any communication between Burr and the Mendel group. Therefore, the “not conclusively demonstrated” statement regarding the essentiality of fat almost certainly was meant to apply to Mendel’s results, not to Burr’s results. When considered in this light, the paper from the Mendel group is far less confrontational than is often implied, although it undoubtedly was disconcerting for Burr to see the “not conclusively demonstrated” conclusion of this world-famous laboratory in the same issue as his own paper.
Burr states that Evans put his laboratory to work to prove him wrong. However, in studies published between 1932 and 1934, the Evans group reproduced Burr’s findings and credits him with the original observations, clearly stating in a 1934 paper that they had extended Burr’s work . Burr also stated in 1980 that Sir Jack Drummond said that the essential fatty acid conclusion was wrong and set his laboratory to work to find the correct answer. However, there appears to be no publication from Drummond’s laboratory that refutes Burr’s results. In 1931, Hume and Smith in London confirmed that rats on a fat-free diet develop a scaly tail, but they attributed this to a deficiency of a B vitamin present in yeast, not to the absence of fat. However, in further studies, Hume et al. reproduced more of the essential fatty acid deficiency syndrome in rats and demonstrated that methyl linoleate cured the disease, thus confirming Burr’s results.
A detailed review in 1937 by Anderson, a coauthor of the 1929 paper from Mendel’s laboratory, listed many papers that confirmed Burr’s findings and stated that: “Burr and Burr…. presented for serious consideration a hitherto unsuspected possible role of certain specific fatty acids in the animal organism.” Burr considered this as a “note of skepticism”, and the caution implicit in this statement probably reflected a lingering doubt by the remaining members of the Yale group. However, some skepticism probably was justified, even as late as 1937, because proof that linoleic acid cannot be synthesized by animals was not obtained until isotopes became available for metabolic studies at the end of the 1930s.
In retrospect, it is easy to understand why Burr’s findings were greeted initially with considerable skepticism. These were not trivial findings about some esoteric problem; rather, they dealt with a central question intimately related to the high-visibility vitamin research of that era, and some of the most prominent figures in biochemistry and nutrition had a stake in the outcome. The ingredients for controversy were there, a relatively young and inexperienced investigator who was disputing the long-accepted findings of the experts.
While Burr admitted that he was disturbed by the initial doubt, his results were confirmed and generally accepted within a few years, and requests for reprints came to Burr from around the world.
The Essentiality of Linoleic Acid
In 1931, Burr reported that linoleic acid was not synthesized from carbohydrates in the rat, and Green and Hilditch subsequently found that the cow also did not synthesize linoleic acid from dietary components. These nutritional observations were confirmed in the late 1930s by Schoenheimer and Rittenberg in their metabolic studies with deuterated water in mice. They found that saturated and monounsaturated fatty acids were labeled with deuterium, but linoleic acid was not, proving that linoleic acid was derived from the diet.
Investigators concentrated on the effects of linoleic acid after Burr’s findings were confirmed, and disregarded the possibility that products synthesized from it might have essential functions. By the late 1930s, however, nutritional studies demonstrated a linkage between linoleic acid and arachidonic acid (20:4ω-6). Nunn and Smedley-Maclean, in London, found that arachidonic acid increased in the liver when rats on a fat-free diet were fed methyl linoleate. These findings were confirmed and extended in the 1940s by Holman and Burr, who developed the alkali isomerization spectrophotometric method to measure individual polyunsaturated fatty acids in a fatty acid mixture. They found that tissue levels of arachidonic acid decreased when rats were fed a fat-free diet and increased when corn oil was added to the diet. Further evidence that arachidonic acid was synthesized from linoleic acid was obtained in rats fed pure linoleic acid.
Fatty acid chain elongation and desaturation were not known in the 1940s, and Burr, Holman, and their associates puzzled as to the how two additional double bonds could be added to convert linoleic acid to arachidonic acid. The answer was provided between 1953 and 1960 by an elegant series of studies with radiolabeled compounds carried out by Jim Mead and colleagues at the University of California, Los Angeles. Mead and coworkers initially found that [1-14C]acetate was incorporated into arachidonic acid, but not linoleic acid, and concluded that arachidonic acid was formed by elongation of linoleic acid. They confirmed this by showing that [1-14C]linoleic acid condensed with acetate to form radiolabeled arachidonic acid. They subsequently demonstrated that γ-linolenic acid (18:3ω-6) was an intermediate in the conversion of linoleic to arachidonic acid, and that dihomo-γ-linolenic acid (20:3ω-6) was the intermediate in the conversion of γ-linolenic to arachidonic acid. The pathway determined by Mead and coworkers:
was subsequently extended by showing that arachidonic acid can be converted to two 22-carbon fatty acid products, 22:4ω-6 and 22:5ω-6.
Nutritional studies done in the late 1930s and early 1940s indicated that arachidonic acid, like linoleic acid, was an essential fatty acid. Methyl arachidonate was found to be more effective than methyl linoleate in promoting weight gain in rats fed a fat-free diet. Furthermore, the skin lesions in the essential fatty acid-deficient rats were cured by feeding methyl arachidonate, and the reproductive abnormalities were cured by ethyl arachidonate.
Mechanistic Basis for the Essentiality of linoleic Acid
Essentiality in the first half of the 20th century was based on the maintenance of normal physiological function and the prevention of disease. While Burr did not determine the biochemical basis for the essentiality of linoleic acid, he stated in 1929: “If fatty acids are responsible for cures, we must assign them a function far more subtle than the production of 9 Calories/gram.”
Burr did not specify what this more subtle function might be, but it seems likely from this statement that he envisioned biochemical effectors similar to the lipid mediators that were eventually shown to be synthesized from essential fatty acids. The mechanistic breakthrough came when Burr was no longer active in fatty acid research. In 1964, Van Dorp’s group at the Unilever Research Laboratories in Vlaardingen and Bergström’s group at the Karolinska Institute in Stockholm independently showed that arachidonic acid was converted to PGE2. Van Dorp stated: “It may even be possible that the actual function of essential fatty acids is to act as precursors of prostaglandins.” “…the symptoms of essential fatty acid deficiency at least partly are due to an inadequate biosynthesis of the various members of the prostaglandin hormone system.”
Bergström’s group also demonstrated that dihomo-γ-linolenic acid was converted to PGE1, indicating a further linkage between linoleic acid, its ω-6 fatty acid elongation and desaturation products, and the formation of the PG biomediators. In addition to serving as the substrate for the production of homo-γ-linolenic and arachidonic acids, linoleic acid is required to generate the ω-hydroxyceramides that covalently attach to epidermal proteins to form a barrier that prevents water loss through the skin.
Essential Fatty Acids in Humans
Burr and his student, Arild Hansen, participated in a 1938 study to determine whether linoleic acid was essential for humans. They observed 40% decreases in serum linoleic and arachidonic acids in a healthy adult male after 6 months on a nearly fat-free diet, decreases that were similar to those seen in the essential fatty acid-deficient rat. Although no harmful effects occurred, except for gradual weight loss, it was concluded that clinical symptoms of essential fatty acid deficiency would have developed if the diet had been continued over a prolonged period.
For the next 20 years, the evidence that humans require essential fatty acids remained indirect and was based entirely on the fact that the serum fatty acid changes in poorly nourished humans were similar to those that occurred in experimental animals. However, more convincing human evidence was obtained in 1958, when skin abnormalities were observed in infants fed a low-fat diet. Addition of saturated fat was not helpful, but the skin symptoms were cured when linoleic acid was added to the diet in the form of trilinolein at 2% of calories. Addition of linoleic acid also reversed the low diene and tetraene content of the serum. 5,8,11-Eicosatrienoic acid, the triene that accumulates in essential fatty acid-deficient rats, also decreased in the serum of the infants when linoleic acid was added to the diet.
Further studies indicated that the minimum requirement for dietary linoleic acid in the young infant was 1% of calories, and the optimum amount was 4%. However, some skepticism regarding whether essential fatty acids were required by humans existed until long-term parenteral nutrition was introduced in 1968. Essential fatty acids were not included in the parenteral nutrition solutions that were used initially, and cases of human essential fatty acid deficiency occurred. An adult male who was treated in 1971 with a fat-free intravenous solution developed the plasma phospholipid fatty acid signs of essential fatty acid deficiency and a skin rash. These abnormalities were reversed when a soybean emulsion containing 86 g/l linoleic acid was added to the parenteral solution. Likewise, essential fatty acid deficiency that developed in infants treated with parenteral nutrition was cured when Intralipid®, which is rich in linoleic acid, was added to the parenteral solution. Thus, it became obvious during the 1970s that linoleic acid was also an essential nutrient for humans.
Essentiality of ω-3 FATTY Acids
In 1931, Wesson and Burr reported that like linoleic acid, its 18-carbon ω-3 analog α-linolenic acid (18:3ω-3), was not synthesized in the rat. This finding was confirmed at the end of the decade by Schoenheimer and Rittenberg’s metabolic studies of deuterium incorporation into lipids. Furthermore, as shown in Fig. 4, which is reprinted from Burr’s 1932 paper, α-linolenic acid was effective in stimulating weight gain in rats on an essential fatty acid-deficient diet. Based on these results, Burr concluded that α-linolenic acid is also an essential fatty acid. However, other investigators found that methyl linolenate was only one-sixth as effective as methyl linoleate in promoting weight gain, and that ethyl linolenate did not cure the skin lesions or facilitate reproduction in essential fatty acid-deficient rats. Furthermore, α-linolenic acid competitively inhibited the effectiveness of linoleic acid in preventing the symptoms of essential fatty acid deficiency. These findings created uncertainty as to whether α-linolenic acid and ω-3 fatty acids were essential, and it took almost 50 years and the work of many other investigators to overcome these doubts.
Evidence that α-linolenic acid is an essential nutrient became convincing only after EPA (20:5ω-3) and DHA (22:6ω-3), which are synthesized from α-linolenic acid, were shown to have important functional effects. Nutritional experiments done in rats and chicks in the late 1930s and 1940s indicated that α-linolenic acid was converted to more highly unsaturated fatty acids that contained five and six double bonds. Klenk and Bongard, in Cologne, reported that a 22-carbon fatty acid containing six double bonds was enriched in brain phosphatides in 1952; Hammond and Lundberg, at the University of Minnesota, purified the DHA from hog brain phosphatides and determined its structure in 1953; and Klenk determined the metabolic pathway for the conversion of α-linolenic acid to DHA8 in 1960.
In 1961, Biran and Bartley, in Oxford, showed that DHA was contained in membrane-bound organelles isolated from brain, and Fred Snyder’s group, in Oak Ridge, extended these findings by showing that DHA was highly enriched in synaptic membrane phospholipids. This suggestion that DHA might play a role in neurotransmission was confirmed by Gene Anderson and colleagues, in Houston, who showed in 1973 that DHA, which is abundant in retinal phospholipids, facilitated the electrical response to visual excitation. These striking findings demonstrated that ω-3 fatty acids are functionally important. However, the prevalent opinion in the 1960s and early 1970s was that ω-3 fatty acids had no unique or essential function and were present in the body simply because they were contained in the diet. Because of the general lack of interest in ω-3 fatty acids at the time, these seminal results had very little impact when they were initially reported.
In 1964, Bergström’s group demonstrated that EPA was converted to PGE by a sheep vesicular gland homogenate, and they subsequently detected PGE in human seminal plasma. However, investigators were focused on PGE2 and PGE1 at that time, and these findings were hardly noticed. In 1976, Phil Needleman and colleagues in St. Louis found that PGG3/PGH3, the endoperoxides synthesized from EPA by sheep seminal vesicles, were converted to thromboxane (TX)A3, and that unlike TXA2, the corresponding arachidonic acid product, TXA3, did not aggregate platelets. Needleman’s laboratory also showed that either PGG3/PGH3 or a PG synthesized from them by coronary arteries had vasoactive properties. Again, because there was little interest in ω-3 fatty acids, investigators focused on results with the corresponding arachidonic acid products that also were reported in these papers and overlooked these striking EPA findings.
The widespread perception that ω-3 fatty acids had no important functions changed abruptly in 1978 when Jørn Dyerberg and H. O. Bang in Aalborg reported that the incidence of myocardial infarction was very low in Greenland Eskimos whose diet consisted of marine lipids rich in EPA and DHA. They found that the plasma of the Greenland Eskimos contained large amounts of ω-3 fatty acids as compared with plasma of Danish Caucasians, and the plasma phospholipids of the Eskimos contained high levels of EPA but very little arachidonic acid. Furthermore, the Eskimos had low levels of plasma cholesterol, triglycerides, and atherogenic lipoproteins, their high density lipoproteins were elevated, and they had an increased bleeding tendency. Dyerberg and Bang found that EPA inhibited platelet aggregation, and they showed that the cyclooxygenase in vascular tissue produced an anti-aggregatory PG from EPA. They concluded that the incidence of myocardial infarction was low in the Greenland Eskimos because EPA protected against thrombosis by inhibiting platelet aggregation by competitively inhibiting the conversion of arachidonic acid to TXA2, being converted to TXA3, or being converted to an inhibitory PG by the vasculature. Thus, the findings of Dyerberg, Bang, and their colleagues established a connection between EPA and PGs, plasma lipoproteins, thrombosis, and atherosclerosis, topics at the forefront of vascular biology and lipid research in the 1970s and 1980s, and the biomedical world suddenly realized that ω-3 fatty acids were important.
Interest initially was centered on EPA because of the eicosanoid and thrombosis connections. However, DHA ordinarily is the most abundant ω-3 fatty acid present in the tissues, particularly in the retina and brain, and emphasis gradually shifted to DHA as results indicating that DHA had a vital role in the nervous system accumulated. It became apparent by the end of the 1990s that the requirement for DHA probably is the primary reason why ω-3 fatty acids are essential. This tentative conclusion was supported by subsequent findings indicating that DHA enhances cognition and synaptic function, and that it is converted to lipid mediators that facilitate the resolution of acute inflammation, provide neuroprotection, and promote hippocampal development.
Evidence for the essentiality of α-linolenic acid in humans was obtained in 1982 by Ralph Holman and colleagues. They observed that a 6-year-old female who had a 300 cm intestinal excision developed neurological symptoms during treatment with a parenteral nutrition emulsion containing 76% linoleic acid, but only 0.66% α-linolenic acid. When the α-linolenic acid content of the emulsion was increased to 6.9%, the DHA in the serum phospholipids increased from 1.54 to 4.35%, and the neurological symptoms were alleviated. The implication that α-linolenic acid was the essential factor was questioned, and it was suggested that the neurological abnormalities were caused by a deficiency of the elongation and desaturation products of α-linolenic acid. In response, Holman, Johnson, and Hatch agreed and stated: “We do recognize that probably the essentiality of linolenic acid resides in the polyunsaturated fatty acids formed from it, just as is the case for the linoleic family of polyunsaturated fatty acids. …We therefore suggest that linolenic acid is a required dietary nutrient for humans and that ω3 polyunsaturated fatty acids are required for normal nerve function.”
Additional clinical studies demonstrated that DHA increased visual acuity and cognitive function in human infants, providing further evidence that the requirement for DHA in the nervous system is a major reason for the essentiality of ω-3 fatty acids.
The discovery of essential fatty acids is one of the great advances in lipid research. It reversed the commonly held belief that dietary fat was merely a source of energy and fat-soluble vitamins, and established fatty acids as essential dietary components. The impact of this discovery is indicated by the more than 46,000 publications currently listed in PubMed under the heading of essential fatty acid, the importance of essential fatty acids in membrane properties and signal transduction, and the potent effects of the lipid mediators produced from arachidonic acid, EPA, and DHA. While George Burr received some recognition for his paradigm-changing discovery, it was modest compared with the honors received by his contemporaries who made major discoveries related to dietary fat.
Several factors contributed to Burr’s failure to achieve a level of prominence equivalent to that of his contemporaries. New findings about fatty acids were not considered newsworthy because fatty acids were commonplace, whereas discoveries about vitamins attracted widespread attention because vitamins were at the forefront of biomedical research in the first half of the 20th century. A contributing factor was that Burr kept working quietly to accumulate the evidence needed to strengthen his discovery and did not seek the limelight. Furthermore, Burr decided to pursue his interest in plant biochemistry in 1956 and moved to Hawaii and then to Taiwan, and he was no longer involved in lipid research during the 1960s and 1970s when the PG and ω-3 fatty acid discoveries stimulated widespread interest in essential fatty acids.
Burr was appointed as a consultant to the Royal Swedish Institute for Scientific and Engineering Research in 1946, and he was invited by the Nobel Foundation to submit a nomination for the Nobel Prize in Physiology or Medicine. This obviously pleased him greatly, because it is one of the few honors that he mentioned in his autobiographical material. The 1982 Nobel Prize in Physiology or Medicine was awarded to Sune Bergström, Bengt Samuelsson, and Sir John Vane for their discoveries concerning PGs, and while Burr was not included, it must have pleased him to know that his landmark discovery of essential fatty acids would eventually lead to findings worthy of this ultimate honor. (Section B is a quote of the entire article by Spector, Kim, 2015. I omitted their references since I reference them).
In this introduction to fats and the determination of total meat content, we reviewed the calculations used for the theoretical calculation of meat content, we did the briefest of introductions to lipids as a macro molecule, and some of its functions. We also quoted the Spector, Kim article (2015) which deals with the history of determining the nutritional value of fat. More articles on fat as part of total meat content follows.
Khan Acadamy https://youtu.be/Ezp8F7XJHWE and a lecture given by Hazel Sive at MIT and made available through their OpenCourseWare program. Marcus, J. B. M.. Lipids Basics: Fats and Oils in Foods and Health, published in Culinary Nutrition, 2013 Pelley, J. W.. 2012. Fatty Acid and Triglyceride Metabolism. Published in Elsevier’s Integrated Review Biochemistry (Second Edition), 2012
Protein Functionality, the Bind Index and the Early History of Meat Extenders in America
Eben van Tonder
10 April 2020
In the meat industry in most parts of the world, it is customary to use non-meat ingredients in meat products, especially in comminuted sausages and lunch loaves. I know that here in Southern Africa, the indigenous tribes have been using ground peanuts (and presumably other groundnuts) as meat extenders for millennia before any European settler arrived here.
I can only imagine that this must have been the case with primitive people around the world wherever there was a shortage of meat.
Who popularised this in the West is a question that intrigued me. Off the bat, as one can imagine, these non-meat ingredients were probably introduced in countries where food scarcity was common or in times when food shortages forced humans to “stretch” the little meat they could get their hands on, such as during times of war. In this article we briefly introduce the functionality of meat protein and ask if we can identify such a movement with the inclusion of meat extenders or replacers to pure meat in America during one of the major wars they were involved in. The two prime candidates must surely be the two world wars and especially the second when huge food shortages were experienced in America and around the world.
The Functionality of Meat Proteins
The first question is if meat protein on its own is not sufficient to bind comminuted meat in sausages and lunch loaves. Can a stable emulsion be formed without the use of non-meat additives such as soya isolates and concentrates and the use of different stratches either as emulsifiers or stabilisers? This includes the use of bulking agents such as rusk, which is in reality a meat extender. This is a level of detail that I was hoping to get into a bit later in a subsequent article, but it explains my point, namely that meat proteins on their own, they have the ability to bind meat extremely well, depending on the muscle and the animal species.
Generally speaking, you will see from what follows that beef meat protein in general provides the best bind and pork, less so due to the higher fat percentage which interferes in binding, especially in emulsions.
There is a major difference between the functionality of different muscle groups in pork and even between different animals. The sausage producer is interested in how these different proteins bind. We therefore present the concept of a “bind constant” (functionality coefficient) that was developed to measure this and a “least-cost formulation” (linear programming) computer program to manipulate the model and minimize cost.
The man who pioneered the large-scale use of these technologies is Robert L. Saffle, during his tenure at the University of Georgia. He did not invent any of the techniques, but was the one man responsible for propagating its use. He also standardized their use, documented their workability and educated and encouraged processors to use it.
He was very successful at this and largely due to his work, meat processors throughout the world recognize the word “bind” as having the basic meaning of the capability of meat to bind the sausage together. The value is referred to as the “bind constant,” “bind value” or “bind index.”
Proximate Analysis and Functional Indices of Various Meat Materials
What follows is a compilation of all meats tested by Saffle and his co-workers, in particular John A. Carpenter at the University of Georgia. It gives the proximate analyses and average measured bind/colour indices. I included the bind index values in the first column because I wanted to show them in descending order and I separated it for different species.
Compiled by J. Carpenter, R. Saffle, H. Ockerman, Anderson & Bell and slightly modified by myself.
When you look at pork, the highest bind value is from the shoulder muscle. The blade is from the lower shoulder.
Labudde and Lanier (1955) put a date to the recognition of when differences in binding quality between different meat cuts were recognised when they say, “It was well recognized by the 1950s that certain kinds of meats bound the comminuted sausage more tightly together than other kinds of meats.” I wonder what my friends in Germany would say about this statement. I believe it was recognised probably hundreds of years before the 1950s.
They accurately report on early classification of meat binding ability. “Cuts of meat were classified into gross categories, such as good binders (bull meat, cow meat), poor binders (hearts, cheeks, fat meat) and fillers (lips, tripe, stomachs)” They are correct when they state that “sufficient lean meat of good “bind” was known to be needed to make the meat paste hold together during cooking and to develop a minimum acceptable level of firmness at the end.” (Labudde and Lanier, 1995) This is my main thesis! The question is how and when did this change?
Dr. Francois Mellett, who was trained in Germany (did his doctorate in German) and who trained German butchers in the Master program, tells me they don’t work with startches in sausage making in Germany. At least, not when he studied there. Another German Master Butcher, Gero Lutge tells me that his dad, who was also a master butcher, used no extenders and that it is not very common in Germany. It was actually these two comments that set me on this journey to unravel what is going on. The German, and I assume, Central, North and East European traditions all concur on this point in stark contrast to the rest of the world where it became the norm to use stabilizers and emulsifiers (extenders) in sausage production.
The matter becomes wonderfully complex because it addresses matters like affordability and the quality of raw material, but what a journey!
There is a personal preference that creeps in here. I am personally not thrilled with non-meat additives to the meat I eat. Using meat replacers and additives is something I do as a meat producer, but I am not happy about it and I try, wherever possible, to rely on equipment and its proper handling together with a thorough understanding of meat to drive our innovations and not, in the first place, reach for the handbook of non-meat extenders and substitutes. This is a grave mistake.
This is another personal reason for this study. I want to be very clear in my mind on what is the best way to use equipment to allow the meat itself to do the bulk of the work.
I am a severe asthma sufferer. A specialist asked me one day if I religiously use the best medication to keep the condition under control to which I responded in the affirmative. To my surprise, he was not happy with that answer. Any chemical you put in your body, no matter how serious a condition you are trying to manage, is always a bad thing. He encouraged me to continually try and develop an alternative, more natural way of managing the condition. He even suggested that I try to reduce my reliance on medication. He suggested that I should determine when I can control the symptoms without medication and when I can no longer do that and I must rely more heavily on medication. Over the years, I have headed his advice to great benefit.
Most of the additives we are talking to in the meat are natural products themselves, which is why it is allowed, but the principle remains the same.
Before anything became “industrial”, it was first used in the home and meat and meat production is a prime example.
-> Home use of Binders
As every major industry we have today, it all started in the home. The following Q & A appeared in an American newspaper in 1950. Mrs GRH wrote in with a question about her meat loaf that is not sticking together.
The advice from the chef is that Mrs. Mrs GRH either did not use a binder or used too little of it. The binders they suggest she should have used are thick white sauce, bread crumbs with a liquid, cooked rice and/or mashed potatoes. They suggested “good old fashion kneading.” Lean meat, 2 pounds, is suggested and add 4 tablespoons of flour, 1½ cups of milk and 1 cup of soft bread crumbs or mashed potatoes. They suggest two kinds of ground meat for flavour (beef and pork). As we have learned, beef added to the pork would also enhance the binding. Dice and fry ¼ pound of mildly salted pork till it is crisp and light brown, and add it for flavour, as show-pieces and mouth feel. The celery, onions and other seasoning is cooked in the salt pork dropping to develop the flavour.
This “home-level-technology” of binders, how long has this been part of the human cultural and technological matrix? One will have to survey its prevalence in cookbooks since the time of the writing of the first one. I had a look at references in the “First American Cookbook” published in 1796 by Amelia Simmons.
Several interesting things catch your eye as you work through this historical document. For starters, there are no sausages. Second, the use of binders is used widely, especially grated bread, butter and eggs. In her stew pie she uses a shoulder of veal, slices of raw salted pork and half a pound of butter. It’s not our focus here but note the common use of veal. I find the same in German cookbooks of this time. Her turkey stuffing calls for grated wheat loaf, butter, finely chopped salted pork and eggs. For meatballs she uses veal, grated bread, salted pork.
-> Meat Binders for Industry (presumably for sausages)
The article below testifies to the use of binders in making hamburgers
I am not sure exactly what the advertisement above is saying. Is the Ground Beef Chuck the binder? In which case they are advertising the use of a cheaper meat cut (chuck) to use for hamburger patties, which is better than using other binders (non-meat). Either way, it shows the “hot topic” during World War II when severe food shortages impacted the world at large, including America. More about this later. (I assume Binders is not the surname of the well-known meat processor of this time, R. Binder Co., because as far as I can see he always spelled his name, when used in this way, with an apostrophe “s”. It could have been a typing error when the newspaper did the typesetting 🙂 )
-> List of Newspaper References with the word “meat binder”
The Second World War was from 1939 to 1945. Severe food shortages occurred during the war, but especially towards the end.
To ease the shortage of bread, they recommended housewives to substitute bread with potatoes. This includes potatoes as binder.
From 1943 (two months before the start of the War)
The term “Meat Extenders” was used synonymously with “Binder”.
Pre-1943 references to Binders
There are several pre-1943 references to meat binders, but all of them refer to butchers’ twine. The one I give above is the least clear, but it is easy to see how the reference is not to binders as we are discussing here.
By the 1970s, meat binders were being discussed as part of the American meat landscape. The article below is a good case in point.
The Crucial Year of 1943
The watershed year for the introduction of meat binders and extenders into the USA seems to have been 1943. Here is an article from that year when a group of women belonged to the Matoy Home Demonstration Club. These clubs (also known as homemaker clubs, home bureaus or home advisory groups) were a program of the U.S. Department of Agriculture’s Cooperative Extension Service, which had the goal of teaching farm women in rural America better methods for getting their work done. This meeting, crucially during the war, was probably arranged to introduce ways to deal with wartime food shortages.
Other clubs received training on meat substitutes and extenders during the same time. Interesting – the fact that meat extenders and substitutes were used in the same sentence.
They held yet another club where Miss Pearl Winterveld was doing the demonstrations during this time.
Another club where Miss Pearl was doing her magic reported on their training.
Another two clubs reported demonstrations for meat extenders and meat substitutes in the same publication. This is remarkable! The photo below, courtesy of the Cornell University Library – shows a meat canning demonstration at a meeting of the Akron Home Economics Club on December 19, 1916.
The Alexander City Outlook from Alabama reported in 1944 several demonstrations along the same line as listed above at Home Demonstration Clubs. The Dadaville Record, also from Alabama, reported similarly on demonstrations of meat extenders and meat replacers in that same year at various club meetings.
By 1946 American soldiers started to return from Europe and clubs continued to spread the “gospel of meat extenders and meat replacers”. In Alabama, the Wetumka Herald of 31 October 1846 reported along exactly the same as in 1943, 1944 and 1945 that demonstrations through the clubs were held at 6 locations.
What were these meat extenders and binders?
An article from 27 March 1943 gives us the detail of what was being demonstrated to the American housewife following that same year.
The author emphasises the fact that knowledge is required to use these meat extenders. He mentions that meat extenders were, at the time of writing, already a household name in America. Still, I suspect that it did not extend much further back then, the beginning of the war, and it could not have been generally true if one takes into account the enormous effort that it took to spread the gospel of meat extenders following 1943.
Anyone wondering if the meat extenders included some magical products such as was developed by Carl Lindegren with his wife Gertrude Lindegren and reported on by the same newspaper in August of the same year when he boldly claimed that through yeast cell technology, they were able to produce “synthetic meat” – if you are expecting this, you are mistaken. The meat extenders that was introduced to America was exactly what we still use today. The key was vegetable sources of protein which included legumes, nuts, cereals, vegetables, and wheat. Soya was identified as having the highest protein value. To the housewife this gave them the option to use dried beans and peas, cooked rice, macaroni and other cooked pastes, nuts and nut butters, fresh or canned peas, corn or lima beans, potatoes, wheat flours, bread and crackers.
If the housewife used extenders with incomplete proteins, it was widely suggested in several newspaper reports to add to the diet elements with essential amino acids. They suggest that they add eggs and milk products to their diet (which are binders in their own right).
The drive for meat extenders was directly related to the food shortages as a result of the war. Brands such as Kellog’s All Bran which is a household name to this day, were marketed as meat extenders.
The evangelists of meat extenders and replacers in the USA, from 1943 onwards, were the US Department of Agriculture through their program of Home Demonstration Clubs. It is then because of the war that meat extenders are commonplace in a large part of the world, including South Africa. I remember a story told by a South African meat master in his own right, Roy Oliver, whose memories goes back to the 1960s, that academics from meat science institutes in the USA regularly visited South Africa and encouraged industry to use meat binders, extenders and emulsifiers on an industrial scale. They would send him various starches and soya products to work with and call him weekly to check on his progress, particularly taking note of the inclusion of these various emulsifiers and stabilisers. He had to test this in meat emulsions made in the bowl cutter.
This in and off itself is an important historical clue as I suspect that South Africa was easier to access for many of these academics from the USA because of our historical close relationship with one country in the region I suspect was initially responsible for using serials, grains etc. in meat emulsions, namely Russia.
One question I am most asked about Gammons / Hams is how to cook it. In South Africa, we call hams, gammons. I will call it gammons for the sake of this discussion.
Boneless or Bone-in
Bone in gammons are better than boneless. The bone adds to the flavour profile and presentation. It’s also ideal to flavour soups or broths after you enjoyed the gammon.
A good compromise is semi-boneless gammon gammon. The shank bone is removed but the leg bone is left in. It makes it easier to carve, but the benefits of bone-in are still there.
Injected or not Injected
Select a gammon with no added water. Producers will inject salt, spices and curing agents. A good rule of thumb for a quality product is that the weight after injection and smoking should be the same as before it was injected. On average, a gammon looses about 10% moisture during smoking and drying (depending on the producer) in the factory and injection should therefore not be over 10% of the initial weight. The label should show no added water added. It should read “100% pork meat.”
Cooking in water?
Be careful not to add too much water or wine in the pan while cooking the gammon. If there is too much liquid, the gammon will boil instead of bake. Add about half a cup of water to prevent the meat from sticking to the pan. We do not intend this for basting. The melting fat will keep the meat moist.
Cover it Up!
The secret of good gammon cooking is to cover the gammon with aluminum foil while it cooks. This prevents the meat from drying out.
Making your own glaze is fun and I will add ideas in this post. Send me your suggestions to firstname.lastname@example.org. Try to blend sweet and savoury flavours. A good start is brown sugar, honey and mustard.
Don’t apply it too soon! You don’t want it to burn.
Cooking Procedure – Low and Slow
Pre-heat your oven to 65 deg C/ 150 deg F.
Use a thermometer which is inserted close to the bone to monitor the temperature. Without this, you are flying blind!
How long should it cook? Until its done! The target is an internal temperature of 145 deg F / 63 deg C. No two gammons are the same just as every oven is different. Check it regularly. Overcooking will dry the gammon out.
Ensure you don’t burn it, but you also want to caramelise the glaze. So, the last 15 to 20 minutes – increase the temperature of 450 deg F / 233 deg C. Continue to monitor it very carefully.
Remove from the oven when the thermometer is at 140 deg F / 60 deg C. The meat will continue cooking outside the oven.
Rest the gammon for about 15 minutes after you remove it from the oven. It allows the gammon to finish cooking and the juices to be absorbed into the meat again.
This article is based on the following video. Please remember to send me your suggestions and photos of your gammons to email@example.com or whatsapp it to me at +27 71 5453029.
Photo of Maple glazed ham: https://www.delicious.com.au/recipes/maple-glazed-ham/9d11c830-4ba3-4c85-9c71-51fc1d79f4e2
A very big part of the art of living is family! Here I feature different sets of family photos. The kids are fortunate to have two extra sets of extended families involved in their lives also. Here we feature the families of all the parents, step-parents, uncles, aunts and further extended family.
Oom Jan Kok
Oom Jan is my mom’s brother. He sent me the following set op photos.
Oom Jan stuur hierdie fotos vir ons op 28 Desember 2017. Vir die lys van al Oom Jan se bydraes, besoek Oom Jan Onthou. Ek pos dit als as deel van “Bacon and the art of living” en in besonder, deel van die gedeelte wat handel oor “The Art of Living”.
In hierdie tyd skryf Ouma Santjie die volgende brief aan Ma in Potchefstroom :
Ons het gister jou brief gekry baja dankie, ek was spyt om te sien dat jy so virkoude is, ek hoop darem dit gaan beter, met ons gaan dit goed ons is nou weer baja gesond. Pappie se oor is ook heel te maal gesond. Jy het seker nog nie gehoor dat Aunt Chathrina weer ?n seuntjie het nie, hy is die 23 ste gebore, hy is vndag 8 dae oud, laaste Dinsdag was sy net baja siek toe was ou Green daarheen hy sê dit is ook die griep wat sy het, maar nou gaan dit weer beter. Oom Freek was gister hier, Pieter was ook hier, ons vra vir hom wat is daar hy se daar is ?n bobbejaan ek vra wat is sy naam hy se Fransie
Hendrik van aunt Kotie was mos ook so baja siek, laats Sondag was ou Green daar en Maandag was Dr Heyns weer daar hy het glo Inflamatie, gister het oom Freek gese was hy bietjie beter maar vandag het ek nog nie weer gehoor nie, ek dink die dag met die Vandiesie het hy seker koue gekry want dit was mos so?n nare dag gewees.
Die ou Klein Kaffertjie van ou Viljoen het laaste Vrydag vir Brand, dit was mos so vreeslik koud daardie dag, en die meid het glo buite kant vuur gemaak en toe gaan sy mis optel toe sy sien toe was die ou kaffertjie in die volle vlam, Pappie het toe nog dieselfde middag die dokter daarheen laat gaan maar nog die selfde nag is hy dood.
Dina is vanaand hier, ons was vanmiddag daar en Maria het so aangehou laat sy moet saam kom.
Pappie het daarom die jaard vir die huis Klaar dit lyk net ewe gaaf.
Die hoenders by die windpomp le nog nie eers nie hier by die huis begin hulle nou net tamenlik te le
Oom Attie hulle het Saterdag nag hier geslaap en Miss Boshoff ook sy was saam met oom Attie hulle.
Hoe gaan dit met aunt Miem? Word sy nou al beter en wat se sy sal die dokter haar kan help ?
Mariaatjie was tog te hoog oor die brief wat sy van jou gekry het. Ek het nog nie eers aunt Cathrina se seun gesien nie.
Pappie had mos so ‘n skade met sy skape die Honde was daar onder, en hulle het 9 doodgebyt en nog ‘n hele paar stukkend gebyt. Die arme ou Bok het hulle net so verniel hy sal ook seker nog dood gaan, nou weet hulle nog nie eers wie se honde dit was nie, dis daarom ‘n vreeslike skade.
Nou liewe Susan die nieuws is nou op en ek is al vaak baja groete van Dina, Pappie, Mariaatjie en van mammie.
Jou liefhebbende moeder,
(I retained the original words used in the letter for historical context and accuracy. The word “Kaffertjie” is a derogatory term, the use of which is prohibited by law in SA)
Met vakansie by Bananabeach. VLNR : Cecil, Miemie, Myra en Mike Webb, Sannie, Ma het ek en Pa. Ek vermoed Uysie het die foto geneem. Let tog op die das van Cecil op vakansie geddra het. Ek en Uysie roei saam met maats op ‘n boot in die Riviermond. Ek dink hulle was Opperman.
My Mom’s Photo Album 1 and 2
Marthie en Loomie
Ouma en Ma
My ma se Ouma en Oupa
My Mom’s Photo Album 3 – Photos of my dad, his side of the family, the Kokke and my mom and dad’s wedding.