Further processing of meat

MEAT EXTENDERS

Meat extenders are usually protein additives, defined as non-meat proteins. A wide variety of meat extenders are available for use in emulsion-type sausages to improve consistency and emulsifying and water-binding capacities. They can also serve to enhance protein content, improve processing yields and reduce formulation costs. The most important meat extenders are soy proteins, milk proteins, starch, flours and yeast. The permitted maximum amount of meat extenders in sausage production is usually 3.5 percent and is strictly regulated by law in certain countries.

167. Pre-packed sausages in contact with floor (hygienic fault)

Soy proteins

These are table proteins from soybeans in the form of flours, grits, concentrates and isolates, texturized, untexturized and extruded.

Soy flour is a screened, graded product, obtained after extracting most of the oil from dehulled soybeans.

168. Emulsion mill, dismantled parts lying on floor (hygienic fault)	170. Improper washing apron on the floor (hygienic fault)
169. Water remaining in grinder (hygienic fault)	171. Meat fallen on the floor and reused for processing in cutter (hygienic fault)

Soy grits are particles of larger size, described as coarse, medium and fine.

Soy flours and grits may be defatted, low-fat, or high-fat. Owing to their functional properties (emulsion stabilization, and fat- and juice-binding), soybean flour and grits are used in the production of all emulsion-type sausages, meat patties and canned-meat products. However, both flour and grits give a slightly bitter taste to meat products, which limits their use (up to 2 percent).

Soy protein concentrates are high-protein products (not less than 70 percent). They possess good water-absorption abilities and are used in emulsion-type sausages, luncheon loaves and meat patties (2.5–3 percent).

Soy protein isolates are the most refined form of soy proteins, without water-soluble sugars and other insoluble components. Owing to their highprotein content (minimum 97 percent) they have excellent dispersing, emulsifying, gelling and water-and fat-binding properties. They are used in production of bologna, miscellaneous sausages, canned and dietary meat products.

Textured soy proteins are available in a variety of shapes, sizes, flavours (beef, pork, ham, chicken etc.), textures and colours. They are used as extenders in comminuted sausages, meat patties and canned-meat products. Some physical properties and typical chemical composition of different soy protein products are given in Table 12.

Application of soy proteins

Soy proteins and meat proteins interact differently with salt. While salt aids the extraction of salt-soluble proteins from meat, it has the opposite effect on soy proteins since it prevents their hydration. It is important therefore to add meat, soy proteins and salt in the correct order. Salt should be added only after hydration of soy proteins has been completed. For complete hydration sufficient water must be available and enough time allowed. The soy product/water ratio should be 1:4 or 1:5, with a minimum of three minutes’ chopping with the knives and cutter at the highest speed. Soy proteins may be used in sausage production in dry gel and emulsion forms.

Dry form. Meat is placed in the bowl at slow speed and soy product is added. The correct amount of water is added at the highest speed to allow complete hydration of the soy proteins. When the mix is homogenous, phosphate is added and finally nitrite salt.

TABLE 12
Typical chemical composition of different soy products

Gel. Using soy gel ensures that the soy proteins are completely hydrated. To 15 kg of dry soy product, 60 kg of water is added. Complete hydration can be seen by the appearance of the gel consistency. Such gel, if used in sausage production, must be added to meat batter before fatty tissues and other additives. The remaining gel is stored in a cooler and, if not required until the next day, 2 percent salt is added.

Emulsion. Soy products can be added to emulsion-type sausages in the form of a pre-processed soy emulsion. These can be produced by processing with cold or hot water, depending on whether fatty tissues are used. The ratio between soy product, fatty tissues and water is 1:5:5 for firm and 1:4:4 for soft fatty tissues. In both cases, soy product is placed in a bowl, water is added, and the mix is comminuted to complete hydration (minimum three minutes). Fatty tissue is added and chopping is continued at the highest speed. For better bacterial stability 2 percent salt must be added. Coldprocessed emulsion can be used the same day, but hot-processed emulsion must be chilled overnight in flat trays in layers not more than 10 cm thick.

Milk proteins

These are casein, lactalbumin, lactoglobulin and other serum proteins. Casein is one of the most important proteins, used as an emulsifying agent in sausage manufacturing as caseinate (dry milk-protein isolate). It is a fine white powder with neutral taste and a protein content of approximately 94 percent. Unlike the coagulable soy proteins, egg albumen and blood plasma, milk protein does not coagulate, shrink or form a gel while heating.

If caseinate is added to meat before salt addition, it will surround free fat particles during comminution. Thus, the binding capacity of meat saltsoluble proteins may be enhanced to form a more stable emulsion.

In sausage manufacture, caseinate may be used in three ways:

Prefabricated caseinate emulsion. When making this emulsion, the order of addition, the necessary emulsifying time and temperature, and the protein:fat:water ratio are of major importance.

After the fatty tissue has been comminuted to a fine paste, dry caseinate must be added immediately, followed by all the hot water. After four to six minutes of comminution the emulsion is ready. During the last few rotations 1.5 percent salt is added. For high-emulsion stability it is necessary to reach a minimum emulsifying temperature of 45°C for pork and 50°C for beef fatty tissues. The emulsion must be chilled overnight in flat trays. Next day the emulsion may be added to the meat batter, together with fatty tissues.

The usual caseinate:fat:water ratio for the lower-viscosity caseinate (EM-6) is 1:5:5 and for high viscosity (HV) is 1:8:8. If cooked pork skin is used, the ratio of caseinate:fat:water and skin is 1:8:8:2 for sausages.

Dry powder caseinate may be used when prefabricated emulsion or gel are unavailable. As this is absorbed at the fat-water interface it is absolutely necessary to add caseinate before fatty tissues to ensure that the emulsion is heat stable.

Prefabricated gel is a concentrated solution of caseinate in water. Optimum results can only be expected when the caseinate is completely dissolved in water (1:8). It is recommended to moisten caseinate in the cutter with an equal amount of ice (1:1). After a few minutes of comminution the remaining seven parts of water are added. The gel is used in sausage formulations containing relatively small quantities of fat and in coarse comminuted sausages.

Starch

This is a complex sugar of plant origin. The basic technological function of starch is to absorb released water and juice during heat treatment. The most frequently used starches are wheat, maize, potato, rice and manioc. Starch is used in doses up to 4 percent. During heat treatment of sausages, added starch binds part of the free water and swells, thus decreasing weight losses.

Flour

Wheat flour is the most commonly used binder following hydration. Approximate chemical composition is starch 65–75 percent, gluten 8–14 percent, and water 12–16 percent. If flour is added in sausage formulation, care must be taken to prevent quick decomposition of the sausage mixture. Owing to the activity of flour enzymes, flour is commonly used in lowquality sausages (up to 4 percent).

Yeast

Brewer’s inactivated yeast with the bitter taste removed is frequently used. It is a fine yellow-grey or grey-pink powder, with distinctive taste and smell. Approximate chemical composition of yeast is: 53 percent proteins, 36 percent sugars and 3 percent water.

In the meat industry the most important application of yeast is based on the ability of its proteins to emulsify fat. A heat-stable emulsion is obtained if the yeast, water and fat ratio is not more than 1:5:5. In comparison with soy isolate and caseinate, yeast proteins have a lower ability to emulsify tallow. A heat-stable emulsion with tallow is only obtained with a ratio of 1:1.3:1.3.

Yeast can be used as an emulsifier in cooked and in canned chopped meat products and can easily replace caseinate in paste production. Yeast used in these products may improve their flavour. The content of free amino-acids improves the flavour of the meat product. Yeast also intensifies the flavour of certain seasonings, especially those with hot components.

Yeast extract

This is obtained from special yeasts cultivated on cane-sugar nutrient media. It contains many proteins, amino-acids and B-complex vitamins. It is used for improving the flavour of canned meat.