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.
Protein options in formulating recipes (source – Mellett, who happens to be the same Dr. Mellett, who co-authored the Mapanda study, 2015)
|Protein Source||Rand Price in SA||% Protein||Rand / kg Protein|
|Soya / TVP||14.00||48%||29.17|
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 an extent 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 skin or 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!
-> Counting Nitrogen Atoms – The History of Determining Total Meat Content Before we get down to business, I examine the history of the development of the concept of Total Meat Equivalent and the equations which are laid down in legislation.
-> Protein Functionality: The Bind Index and the Early History of Meat Extenders in America The first consideration is the fact that different meat sources, and different parts of the carcass, have different binding functionalities. Here I also develop the history of binders, fillers and meat extenders in America and the birth of the analog product.
-> Hot Boning in America First step towards a better understanding of the binding of proteins to each other and water.
-> Emulsifiers in Sausages – Introduction. Understanding the role and chemistry of non-meat emulsifiers, extenders and fillers is currently widely used in South Africa.
-> MDM – Not all are created equal! Starting to understand the base meat material used in fine emulsion sausages in South Africa.
-> Soy or Pea Protein and what in the world is TVP? Here we start to learn about the functional properties brought to the fine emulsion by soy, pea protein and TVP by first understanding exactly what they are and how they are produced.
-> Poultry MDM: Notes on Composition and Functionality Here we start our detailed consideration of chicken MDM.
Feiner, G. 2006. Meat Products Handbook: Practical Science and Technology, Woodhead Publishing.
Mapanda, C., Hoffman, L. C., Mellett, F. D., Muller, N. Effect of Pork Rind and Soy Protein on Polony Sensory Attributes. J Food Process Technol 2015, 6:2 DOI: 10.4172/2157-7110.1000417
Yada, Y. (Editor). 2004. Proteins in Food Processing. Woodhead Publishing. CRC Press.