Emulsifiers in Sausages – Introduction

Eben van Tonder
2 April 2020

Introduction

In 1988 E. Allen Foegeding presented a paper, Gelation in Meat Batter with the following as the opening paragraph of is presentation. “When frankfurters, hot dogs or bologna are manufactured, the meats are extensively chopped (comminuted) to produce small particles. One can observe a heterogeneous mass of lean and fat transformed into a meat batter of homogeneous appearance. Meat batters are fluid and primarily composed of water, fat and protein. One key element in manufacturing these products is stabilizing the fat and moisture to prevent excessive tosses or product failure. The meat proteins stabilize the fat; therefore, meat batters have historically been defined as meat emulsions. The colloidal chemistry definition of an emulsion – a two-phase dispersion
of immiscible liquids – is a good representation of the raw meat batter.

Meat batters are considered an oil-in-water emulsion (o/w) and much of the pioneering work (see review by Saffle, 1968) focused on factors regulating emulsion stability.” We will return to the work of Saffle.

With this, we introduce the major branch of Meat Science of emulsification. In this short article, we introduce some of the basic terminologies and briefly introduce the concept of an emulsifier and a stabiliser. We look at two emulsifiers and give a list of most common ones used. Even though this is an introductory article, there are major lessons to take into the production plant.

Comminution of Meat

Comminution is the process of reducing material, such as meat, to minute particles or fragments. Sausages are made from meat which has been reduced to various sizes. In general terms, comminution technology relies on working the lean meat component with salt and water so that the maximum meat binding can be achieved along with water-holding properties. Fat should be treated only briefly so that minimal damage is done to its cellular tissue structure. As a general rule, fat should be kept separate and added to the mix as late as possible to avoid this. The lean meat proteins will find it difficult to bind the fat if this can not be achieved (such as in cases where the lean meat and fat can not be separated). In these cases, material with a high protein content is added to beef up the binding properties of the mix. Such materials are soya isolates, caseinate (or other milk derivatives), blood plasma, etc.. Protein extraction works better at warmer temperatures, but the more important issue to consider is micro-control and ice/ water is used. (Ranken, 1997)

Emulsion Sausages

Emulsion sausages are characterised by the inclusion of a finely chopped meat mixture with added water (ice) and salt. A large percentage of the fat is separated from the fatty tissue but it remains bound or emulsified by the lean meat mixture. A homogenous paste is created which gels on heating thus establishing a sliceable mass. Emulsion stability will ensure a “snap” when the sausage is broken in two or bitten into and will prevent cookout. (Ranken, 1997)

It is not unusual for a single emulsified base to be created for the manufacture of a variety of sausages (known in Germany as a brat). Lean meat is the most important source of water-binding capabilities and the less lean meat there are, the more important it becomes to ad a binder to assist in the water-holding capability of the mix. Such binders include dried or frozen whole egg or egg yolk, blood plasma, skimmed milk powder, caseinates and certain whey protein isolates, soy isolates, soy concentrates, soy flours and wheat gluten. (Ranken, 1997) So, the usual sequence is normally applied namely homogenizing (make similar) meat with ice (for temperature control) in a bowl cutter. Next, fat is added in the cutter followed by spices, followed by rusk or other water binders or fillers.

Basic Biochemistry to Understand Emulsifiers and Stabilisers

It is very helpful to understand some of the mechanisms at work in emulsification. Before you work through the following two short clips, it will be very instructive to took at the properties of fats and oils which and to understand why its difficult to bind them with water. For a discussion on this, refer to an article I did on LIPIDS. I did the article as part of a short series on determining total meat content. You can skip the calculations right at the start of the article if this is not of interest to you.

The first video is a basic introduction to emulsions with important lessons.

-> Lessons for the meat processor

1. Smaller holds better and more

When I attended demonstrations of emulsifiers vs bowl cutters, the argument is made that emulsifiers produce smaller particles than a bowl cutter. If this is true, it is important because the smaller the fat particles, the more stable the emulsion will be and the more fat can be added to the emulsion. Therefore, ensure the blades are sharp, that they are all there and enough time is allowed to reduce the fat particles. If oil seeps out of the dispersed phase, one of the reasons may be that the hat has not been reduced to small enough particles.

2. Smaller tastes better

The second implication is smaller particle size relates to flavour. Flavour is tightly connected to the surface area. This is how it works. We know that up to 70% of our perception of flavour comes from aroma. Most aroma molecules are only soluble in fat. The smaller you can get the fat particles in the dispersed phase, the more surface area you are creating for the aroma molecules to dissolve onto the fat surface. This means that there will be a greater and more rapid release into your nose when the emulsion is put into your mouth.

3. Don’t overdo it, and if you insist, there are ways to manage “more”

There is a limit to this as the law of diminishing return starts taking hold. The more fat you add (called the dispersed phase in our example), the thicker the emulsion will become. The volume of the dispersed phase should not be more than 3 times the volume of the water (or the continuous phase). Emulsions are per definition unstable. As you increase the fat (dispersed phase), you are starting to cram the fat together and as this happens, it will start clumping together and float to the surface as the surface tension is being recreated. One way of avoiding it is to stick to the 30% rule as I mentioned above. Another way is to use emulsifiers and stabilisers which is the topic of the following video.

The second video deals with emulsifiers and stabilisers and introduces us to some of the mechanisms behind their efficacy.

-> Lessons for the meat processor

Emulsions are by definition unstable and the way we correct this is by using emulsifiers and stabilisers which are two different things that serve the same goal.

A. Emulsifiers

There are two types of emulsifiers that we will commonly encounter:

1. Amino acid chains with fat-friendly receptors and water-friendly receptors, binding fat to oil. Some amino acids are grouped together in large molecules called proteins. Some proteins act as emulsifiers such as casein found in milk and egg yolk, binding fat and water.
2. The second is phospholipids such as lecithin. Lecithin has a water soilable head and fat soilable tail. An emulsifier with a water-soluble head and fat-soluble tail is called a surfactant. Surfactants decrease surface tension. Surface tension occurs as the result of molecules who don’t like to mix. As a result of this, they align themselves accordingly which creates surface tension or interfacial tension which is the tension between the two interfaces, namely the dispersion phase and the continuous phase. A surfactant reduces this tension by linking them together. It thus reduced or completely remove surface tension. This allows them to freely mix which is the definition of emulsification. Lecithin, like some of the other phospholipids, has the added advantage of a positively charged fat tale. This will repulse other positively charged fat tales and will contribute to fat droplets not coalescing or combining together again.
3. Common emulsifiers are egg yolks (lecithin + protein which is casein with a fat-friendly and water-friendly part), milk and cream (containing casein protein), mustard (containing mucilage which is a powerful surfactant)

B. Stabilisers

Where emulsifiers link fat and oil together, stabilisers get in the way of fat coming together again. Most stabalisers are water-soluble. You will use a stabaliser when you are making fat dispersed into water emulsification. The large molecules of the stabaliser get in the way of the fat and interfere so that the fat does not come together and break the emulsion. Examples of these large molecules are proteins, starch, pectin, plant particles (puree) and food gums. The large molecules will also add viscosity to the mixture.

So, always start with water and add the stabalisers to the continuous phase. This will increase the viscosity of the water. Viscosity itself during emulsification will act as a stabiliser. The thicker the continuous phase becomes, this will create more drag on the disbursement phase which is the fat in this case. This increases the sheering power (which is needed to break up the disbursement phase or the fat) which will decrease the particle size of the dispersed phase. The smaller the particles in the dispersed phase, the more stable the emulsion will be. So, add them to the continuous phase (water) before you even start with the emulsification/ before adding the fat (they are water-soluble after all).

Xanthan Gum is a good example of a stabiliser. It adds viscosity to water and you use very little (about 0.5% by weight of the water), no detectable taste or odour and is effective across a wide pH range. It will also hydrate in both hot and cold water. The most important feature that sets it apart from other gums is that it is shear thinning. At rest, it will be thicker than in shear which is applying force such as stirring or blending.

– Examples of Emulsifiers: E471 – Mono and Diglycerides

The food addative, E471 is a group of synthetic fats that are produced from glycerol and natural fatty acids, from plant and animal origins. It is generally a mixture of several products, and its composition is similar to partially digested natural fat. As a food additive, E471 is mono- and diglycerides of fatty acids (glycerol monostearate, glycerol distearate) that is used as an emulsifier in a great variety of foods.

Monoglycerides and diglycerides are naturally present in various seed oils (Flickinger, et al., 2003). Their concentration is normally low and industrial production is primarily achieved by a glycerolysis reaction between triglycerides (fats/oils) and glycerol. (Sonntag, 1982)

Both vegetable or animal fats and oils are used for these. E471, however, is generally a mixture of several products. Its composition is similar to partially digested natural fat.

“Glycerol monostearate, commonly known as GMS, is an organic molecule used as an emulsifier. GMS is a white, odorless, and sweet flaky powder that is hygroscopic. It prevents the formation of fat bloom on confectionery and truffles. It is applicable to all types of products with water content, and it is particularly recommended for use in water-fat mixtures. You can find it in our body as a by-product of the breakdown of fats, and it is also found in fatty foods. It is largely used in baking preparations to add “body” to the food. One of the most common applications is to give ice cream and whipped cream its smooth texture. Apart from this function, GMS is also used as a thickening, emulsifying, anti-caking, and preservative agent in food additive industry. For industrial uses, it can be used as a emulsifying agent for oils, waxes, and solvents; a protective coating for hygroscopic powders; a solidifier and control release agent in pharmaceuticals; and a resin lubricant. It is also used in cosmetics and hair care products.” (okfoodadd)

-> Is Glyceryl Stearate Dangerous?

“In my point of view, glyceryl stearate is safe and green. The production process is as simple as hydrolyzing a suitable oil feedstock. This is a similar process with making soap which most of you can manage in the kitchen. The process also uses renewable resources and does not consume much energy. Glyceryl stearate is not toxic and readily biodegradable which can be done not only by micro-organisms but by humans. Since glycerys stearate is a by-product of breakdown of fats, the process of breaking it into components is very basic that is one of the body’s major sources of energy and is going on in your body right now.” (okfoodadd)

– Examples of Emulsifiers: Lecithin

From the Greek lekithos “yolk”, lecithin is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which attract both water and fatty substances. It is a phospholipid (see A Basic Introduction to Lipid Chemistry) The main applications are for smoothing food textures, emulsifying, homogenizing liquid mixtures, and repelling sticking materials.

Lecithins are mixtures of glycerophospholipids including phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and phosphatidic acid (Smith, and Hong-Shum, eds., 2011)

Emulsifying Capacity

The exact definition of an emulsion is at issue. Meat emulsions are not considered true emulsions. “According to the emulsion theory for comminuted meat products – water, protein, and fat produce the continuous, emulsifier, and dispersed phase of an oil-in-water emulsion, respectively. The large size of some oil droplets (0.1–50 μm) has led to doubts whether meat emulsions should be considered true emulsions. An alternative model for comminuted meat products is that they are 3–dimensional gel networks with entrapped oil.” (Owusu-Apenten, R. K.. 2004) Most industry professionals and researchers refer to these products as meat emulsions and we follow the same practice.

How do we then define emulsification in meat systems? The emulsifying capacity of protein, a meat suspension or other emulsifying agent is defined as the volume of oil that can be made into an emulsion by a solution or suspension of proteins, etc. under certain practical conditions. Several tests have been developed, the most familiar being the test for emulsification capacity (EC) of Swift et al. which measures the volume of oil emulsified per 100 mg of protein at the point of emulsion inversion. In the Swift test, “melted lard is added from a graduated separating funnel into a blender containing the meat suspension, protein solution or other emulsifiers with the blender running to give a high-speed cutting/ mixing action. An oil-in-water emulsion is formed which becomes increasingly more viscous with further addition of fat until the viscosity suddenly decreases when the emulsion “breaks”.” (Ranken, 1997) The endpoint is thus established from which the emulsifying capacity can be calculated. The steps are informative and important to know.

List of Emulsifiers

The European Food Emulsifiers Association (EFEMA) lists the following emulsifiers.

E 322	Lecithins
E 432	Polyoxyethylene sorbitan monolaurate (Polysorbate 20)
E 433	Polyoxyethylene sorbitan monooleate (Polysorbate 80)
E 434	Polyoxyethylene sorbitan monopalmitate (Polysorbate 40)
E 435	Polyoxyethylene sorbitan monostearate (Polysorbate 60)
E 436	Polyoxyethylene sorbitan tristearate (Polysorbate 65)
E 442	Ammonium phosphatides
E 470a	Sodium, potassium and calcium salts of fatty acids
E 470b	Magnesium salts of fatty acids
E 471	Mono- and diglycerides of fatty acids
E 472a	Acetic acid esters of mono- and diglycerides of fatty acids
E 472b	Lactic acid esters of mono- and diglycerides of fatty acids
E 472c	Citric acid esters of mono- and diglycerides of fatty acids
E 472e	Mono- and diacetyl tartaric acid esters of mono- and diglycerides of fatty acids
E 472f	Mixed acetic and tartaric acid esters of mono- and diglycerides of fatty acids80
E 473	Sucrose esters of fatty acids
E 474	Sucroglycerides
E 475	Polyglycerol esters of fatty acids
E 476	Polyglycerol polyricinoleate
E 477	Propane-1,2-diol esters of fatty acids
E 479b	Thermally oxidised soya bean oil interacted with mono- and diglycerides of fatty acids
E 481	Sodium stearoyl-2-lactylate
E 482	Calcium stearoyl-2-lactylate
E 491	Sorbitan monostearate
E 492	Sorbitan tristearate
E 493	Sorbitan monolaurate
E 494	Sorbitan monooleate
E 495	Sorbitan monopalmitate

Conclusion

The meat technologist and production manager alike must have a rudimentary understanding of these principles. What is important is not to remember all the terminology or to be able to perform all the complex evaluations. Simply knowing that these exist and to have a general understanding of the mechanisms at work will be of great benefit. This briefest of introductions already yielded important lessons to the meat processing plant.

References

From the official site of The European Food Emulsifiers Association (EFEMA), http://www.emulsifiers.org/ViewDocument.asp?ItemId=9&Title=Background

Flickinger, Brent D.; Matsuo, Noboru (February 2003). “Nutritional characteristics of DAG oil”. Lipids. 38 (2): 129–132. doi:10.1007/s11745-003-1042-8.

https://www.okfoodadd.com/Blog/detail/id/47.html
Owusu-Apenten, R. K.. 2004. Testing protein functionality. From Proteins in Food Processing, Woodhead Publishing Series in Food Science, Technology and Nutrition, 2004, Pages 217-244.

Ranken, M. D., Kill, R. C., Baker, C. G. J. (Editors). 1997. Food Industries Manual, 24th Edition. Blackie Academic and Professional

Smith, Jim; Hong-Shum, Lily, eds. (2011). Food Additives Data Book (2nd ed.). Chichester, West Sussex: Wiley-Blackwell. p. 334. ISBN 9781444397734.

Sonntag, Norman O. V. (1982). “Glycerolysis of fats and methyl esters — Status, review and critique”. Journal of the American Oil Chemists’ Society. 59 (10): 795A–802A. doi:10.1007/BF02634442. ISSN 0003-021X.

Sourkes, T. L.. 2004. The Discovery of Lecithin, the First Phospholipid, McGill University, Bull. Hist. Chem., Volume 29, Number 1 (The Discovery of Phospholipids)

Szuha, Bernard F. (1989). “Chapter 7”. Lecithins: Sources, Manufacture & Uses. The American Oil Chemist’s Society. p. 109. ISBN 0-935315-27-6.