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RAW-COOKED MEAT PRODUCTS

Definition: The product components muscle meat, fat and non-meat ingredients, are processed raw (“raw”=uncooked) by comminuting and mixing in a first phase. The resulting viscous mix/batter, upon portioning in sausages or otherwise, is thereafter submitted to heat treatment or “cooking”, in order to obtain a firm-elastic texture typical for ready-to-eat raw-cooked products and to achieve palatability and a certain degree of bacterial stability.

Raw-cooked meat products are mostly manufactured and marketed as sausages in small to larger calibre casings, but are also available as meat loaves, meat balls or as canned products (Fig. 159). Raw-cooked meat products are a very specific group as their processing technology is different from all other processed meat products. The utilization of comminuting equipment such as grinders and bowl cutters is essential in their manufacture, in specific cases also emulsion mills (see page 18, 20, 30).

These specific meat products originated more than 100 years ago from Europe and many variations are now popular in most parts of the world. In fact, in many countries the raw-cooked meat products account for 50% or more of all further processed meats on the market.


Fig. 159: Various raw-cooked meat products. Frankfurter and hungarian (left), sausage in large calibre casing (bologna and ham sausage, right), meat loaf (centre), canned products (frankfurter and luncheon meat, left, behind)

The most common are the small-calibre “Frankfurters” and “Vienna sausage” and the large calibre “Bologna” and “Lyoner”. They all belong to the group of “all-meat” classical raw-cooked meat products, made from muscle meat, animal fat and water/ice as the main components and small amounts of necessary non-meat ingredients (recipes page 400 – 408). Others can be classified as extended raw-cooked meat products as they contain higher amounts of low-cost non-meat ingredients mostly of plant origin for cost-reduction. Some typical representatives of this group are “hotdogs” or “luncheon meat” (page 210, recipes page 410 – 412).

Classical raw-cooked products (recipes page 400 – 408)

These are products of relatively high quality and good nutritional value as they contain meat and fat as the main components and water as the major non-meat ingredient. Ingredients of plant origin, if any, are used in small quantities and do not serve as an extender but as binders, e.g. soy isolate (approx. 2% added) (see page 80).

In contrast to the classical raw-cooked products, extended raw-cooked meat products are of inferior quality as they contain higher quantities of extenders and fillers of plant origin (see page 64). These products are described on page 199.

Principles of manufacture

1 Extract and dissolve solid muscle proteins through physical (chopping) and chemical (salting) treatment of lean meat and blending with water (Fig 160, 161).

Fig. 160: Condition after dry chopping (see page 136). Muscle fibre fragments (red) and connective tissue particles (green) present in mix Fig. 161: Condition after adding salt and water. Most muscle fibre fragments swell through water incorporation (blue) and become gelatinous or solubilized (b), some muscle fibre fragments (a) and connective tissue particles (green) remain unchanged. Water droplets may also be loosely bound between the fragments (blue) (c)

2 Establish a network structure of liquid or gelatinous muscle proteins in the meat batter capable of surrounding and enclosing small particles of fat and binding water (Fig. 162).

Fig. 162: Condition after comminuting and addition of fat. Network structure of gelatinous (b) or liquid (d) muscle fibre proteins (dark red areas) established, fat particles (yellow) coated by protein (bright red). Connective tissue (green) and some muscle fibre fragments (a) unchanged. Water droplets (blue, c) incorporated in protein network

3 Stabilise the muscle protein network through heat coagulation by “cooking”. Core temperature of products should be not lower than 70°-72°C (Fig. 163).

Fig. 163: Condition after heat treatment: Protein network structure becomes rigid and firm elastic (purple areas) through protein coagulation/denaturation. Connective tissue particles (green) swell in size and become softer, may interlink (arrows) if large amounts present

4 Cool products down through immersion in cold water or cold water spray immediately after cooking, pass quickly temperature range from +40°C - +20°C, store in refrigerated rooms (Fig. 164, 178, 181, 182).

Fig. 164: Cooling in ice water (+5°C) of sausages of different calibre (20 mm, 40 mm, 75 mm). Decrease in core temperature depends on calibre of sausage and temperature of cooling water

These are the essential steps in the processing technology for all types of raw-cooked meat products. If instead of classical raw-cooked products specific types of extended raw-cooked meat products are manufactured, the incorporation of the extenders and fillers chosen takes place at phase 2. Examples for extended raw-cooked products are Hotdogs or Luncheon meat. Composition and technology used are described on page 204, and 210.

For phase 1 and 2 of the manufacture of raw-cooked products it is essential that only raw (uncooked) lean meat and fat are used, as pre-cooked materials would not produce the necessary effects of protein solution, protein network building and increased binding of water. Protein solution and network building as shown in Fig. 160 to 163 is achieved through a combination of effects:

At phase 3 the necessary heat treatment is applied. Through adequate heat treatment of the batter (see page 129, 144) filled in sausage casings, cans, or portioned otherwise (e.g. meat loaves, meat balls), the heat coagulation of the liquid or gelatinous proteins in the viscous batter is effected forming a firm cross-linked network structure. This results in a rigid firm-elastic texture of the final product.

For the above reasons the term “raw-cooked” is used for this type of products as in the first phase “raw” processing and in the second phase “cooked” processing is taking place.

Raw material and additives - preparatory steps for processing

Lean meat is the principle raw material for classical raw-cooked meat products. It provides the muscle proteins, which play an important role in the processing technology of raw-cooked products. The lean meat component comprises mainly chilled beef and/or pork, but also poultry meat (turkey, chicken) is becoming increasingly popular for this purpose. Other meats like mutton and venison are less suitable and not commonly used. The same applies to muscular slaughter by-products such as heart, diaphragm and oesophagus.

Lean meat is used in quantities of 30-50% referred to the overall amount of batter for raw-cooked products. Beef forequarters are an important source of lean meat. As most of the lean meat will be finely chopped, also smaller meat pieces (trimmings) obtained during meat cutting can be used (see page 46, 50). Visible fats and hard connective tissues should be removed from the lean parts. The lean meat must be thoroughly refrigerated (+4°C or lower, except in case of processing “pre-rigor” meat, see page 135). In order to quickly achieve a homogeneous batter, the chilled lean meat is pre-minced (3mm grinder disc) prior to comminuting in the bowl cutter.

Note: The lean meat should have a relatively high pH, preferably in the range of 5.7-5.9, as such meat has a better water binding (also called water holding) capacity (WBC/WHC) (see page 7). Chilled meat reaches its lowest pH after 24 hours and thereafter there will be a slight pH-increase, which is favourable for the WBC. Hence it is recommended to use chilled lean meat, in particular beef, three days after slaughter. If frozen lean meat is used, this meat should not be thawed prior to chopping, as thawing will substantially reduce its WBC.

Frozen lean meat should be “tempered”, i.e. raising the temperature to make it softer, but keeping it below the freezing point (-1 - 5°C). It can then be placed frozen into the bowl chopper (upon manual pre-cutting or with frozen meat cutters, see page 31).

Beef, in particular from younger animals, has the best WBC. Good WBC is important to bind the amount of up to 30% of water, which is usually added to the batter to improve texture and palatability of the final products (see page 133). Moreover, the lean meat itself has a water content of 70%, which also must be kept bound. The binding of all this water must remain stable in the sausage mix also during heat treatment, which is the hardest challenge for the water retention capacity. Low WBC results in loss of liquid during cooking visible as an accumulation of jelly under the sausage casing, inside cans etc. (Fig. 165).


Fig. 165: Canned product with separation of jelly and fat

Apart from the water, the meat batter must also retain the fat added. It is again the function of the proteins to keep the comminuted fat droplets dispersed in the batter also during heat treatment (Fig. 163 and 165).

Fat, mainly chilled pork fat, but also chicken, beef or lamb fat or vegetable oil, is used in quantities of 15-30%. Not all animal fats are suitable for this purpose, as some would make the batter too “grainy” (kidney fat) and others too soft (intestinal fat). Back, belly and jowl fat (pork), skin (poultry) and to some extend intermuscular fat (beef) are suitable. Beef fat is generally inferior to pork and chicken fat and should only be used if pure beef products are to be fabricated (see page 12, 43).

Fat is an indispensable ingredient in classical raw-cooked meat products because they make products softer and more palatable and support desirable flavour. In order to achieve a good quality product with typical taste and texture, preferably fresh chilled fats should be used (see page 10). Fats from long cold storage, in particular frozen fats, are less suitable, as they tend to become rancid. Fats should be free of hard connective tissue. The chilled fats are pre-minced (3mm grinder plate) for good immediate distribution in the batter. If vegetable oil is used instead of animal fats, this oil should be chilled but must remain liquid or viscous (Fig. 100).

Other animal tissues

Animal by-products of the non-muscular type, such as internal organs, are not used for raw-cooked products. The only exception is animal skin. Poultry skin, which has a high fat content, can be used as pork fat replacement or as the entire fat component, in particular in pure poultry products. Pork and cattle/veal skin do not contain fat, but connective tissue. Pork skin becomes gelatinous upon cooking and comminuting, and has the property to bind some water and produce a sticky elastic texture. It can be blended to the batter, and this mixture develops good cohesiveness upon heat treatment and cooling. Pork skin is an economic source of protein (nutritionally inferior to muscle protein) and may be used for lower quality and lower cost raw-cooked products (see page 47).

In contrast to all other raw materials for this type of products, pork skin is often added pre-cooked, as pre-cooked pork skin is soft enough to be sufficiently comminuted by the equipment used. Pre-cooking also reduces the high bacterial content of pork skins. In some cases raw-frozen pork skin is finely chopped with ice flakes and added. Poultry skin, used for specific products as a carrier of larger quantities of fat, is used uncooked.

Water is added in quantities of approximately 15-35%. It makes products juicy and easily chewable. Water is not primarily used as “filler” in raw/cooked meat products. It is absolutely necessary as a carrier and solvent for the muscle proteins. Water together with salt and phosphates, which enforce the process, is indispensable for the desired extraction and water binding of the muscle proteins (see Fig. 161). As the protein extraction is best under low temperatures, water is often added frozen as ice to keep the temperature of the meat batter low. Low temperatures are also needed to avoid excessive rise of temperature in the area close to the fast rotating bowl chopper knives. Excessive temperatures there would spoil the ability of affected proteins in water binding and gelation. For quick and even distribution (in order to achieve an instant cooling effect in all parts of the chopping bowl), small-size ice flakes should be used or ice blocks should be crushed into small pieces before being added to the batter.


Fig. 166: Ice flakes

Additives and spices (salt, phosphates, ascorbic acid, various ground spices) are used in dry-powder form and must be stored in a cool and dry place in closed containers and frequently checked for impurities. These additives are used in smaller quantities and need to be accurately weighed to avoid under- or overdosage.

Salt and/or nitrite curing salt serve for salty flavour, solution of muscle proteins and curing colour. Approximately 2% is normally applied (see page 67, 68).

Phosphates assist in solubilizing muscle proteins. Approximately 0.3% is normally used (see page 69).

Ascorbic acid acts as a catalyst in the curing process. Approximately 0.05 – 0.1% is normally used (see page 68).

Note: In the process of chopping, the curing substances get homogeneously blended to the batter so that equal curing is secured. In order to accelerate this curing process, ascorbic acid (or sodium ascorbate or sodium erythorbate) is added to boost the reaction of myoglobin with curing salt (see page 35, 37). Ascorbic acid reacts instantly upon contact with the nitrite. In order to avoid a premature reaction before the nitrite is homogeneously distributed in the batter (which would result in unequal curing), it is recommended to add the ascorbic acid in the final phase of the comminuting process.

Spices may vary, but pepper (in combination with salt) forms the basis for a raw-cooked product seasoning mixture. Other spices are supplementary and are chosen according to the type of the product and local preferences (see page 85, table 3).

Additional measures for proper cohesiveness and water binding

The protein network in the final batter will be the more complete and functional as more meat protein is used in the mixture. To further facilitate the formation of the protein network, where the meat content is low, the following measures can be taken:

Table 7: Typical composition of some raw-cooked sausages
(for definition of raw meat materials see page 45 and 49)

Ingredients %

Beef frankfurter

Mixed
frankfurter

Pork frankfurter

Vienna

Bologna

1

2

1

2

Meats
             
               

• Beef I and II

35.0

30.0

25.0

20.0

--

30.0

25.0

• Pork II

--

--

20.0

20.0

35.0

20.0

--

• Beef fatty trimmings (III)

33.0

20.

--

4.0

--

--

--

• Pork fatty trimmings (III)

--

--

5.0

5.0

5.0

4.0

4

• Beef fatty tissues

6.0

10.0

--

--

--

--

--

• Other by-products

--

--

7.0

8.0

--

--

--

Other ingredients

             
               
• Ice water

21.0

16.0

23.0

22.0

25.0

28.0

24.0

• Meat extenders

2.0

3.0

3.5

3.0

3.0

3.5

3.0

• Phosphates

0.3

0.4

0.4

0.3

0.3

0.5

0.5

Curing ingredients

             
               

• Nitrite salt

1.6

1.8

1.8

1.8

1.8

2.0

2.0

• Sugar

0.5

0.2

0.4

0.2

0.3

0.6

0.3

• Glutamate

0.15

0.2

0.2

0.2

0.2

0.2

0.2

Seasonings
             
               
• Pepper

0.12

0.13

0.3

0.2

0.2

0.4

0.35

• Coriander

0.08

0.1

0.1

0.1

--

0.3

0.15

• Nutmeg

--

--

0.1

0.1

0.1

--

--

• Sage

0.05

0.05

--

0.05

--

--

--

• Cinnamon

0.05

0.05

--

0.05

--

--

--

• Fresh garlic

0.05

0.02

0.1

--

--

--

0.35

• Clove

--

--

0.05

--

0.05

--

--

• Mace

0.1

0.05

--

0.1

--

0.2

0.15

• Ginger

--

--

0.05

--

0.05

0.3

--

Technological procedures

Meat processing techniques changed over the years following improved equipment designs and performances. The methods described below take into account the performance of the equipment expected to be accessible to small or medium scale meat processors in developing countries. The following processing steps achieve satisfactory final products:

The chopping process (Fig. 167)

Step 1 : The lean meat portion is pre-minced and kept chilled (0˚C).

Step 2 : The lean meat is placed in the bowl cutter with the salt and additives for the whole batch. The mixture is chopped for 5-10 rounds without ice. This step is called “dry-chopping”.

Step 3 : Ice is added and the chopping continued at fast bowl chopper speed until the ice is evenly incorporated and a “sticky” lean batter is achieved. Now also the spices are added.

Step 4 : The fat (pre-minced and chilled) is added and the mixture chopped at high speed until a homogeneous batter made of lean and fatty tissues is achieved.

Step 5 : The final temperature of the batter should not exceed +12°C

The extraction of muscle proteins can be further enhanced and a uniform distribution of all components in the mixture accelerated by:

Not all raw-cooked products are entirely made of finely chopped batter. Many products are made of a mixture of finely chopped batter and coarse meat pieces. The coarse meat material can be cut by hand (strips of meat with 1-2 cm diameter) or pre-minced (5-8 mm hole size in grinder disc). It is usually pre-salted and spiced before incorporated in the finely chopped batter. Bigger meat pieces are separately cured (preferably in curing brine over 24 hours) and should be manually massaged or tumbled to extract protein from the surface of the meat pieces, which after heat treatment, makes the coarse pieces adhere firmly to the surrounding batter (see Fig. 168).


1) As this operation is accompanied by a certain temperature increase, the temperature of the batter produced in the bowl cutter should remain below 10°C prior to passing the batter through the emulsifying machine.


Fig. 167: Production steps for finely chopped batter


Typical composition of finely chopped product: Ice, fat (above), beef, pork (below)


Additives and spices: Phosphate, ascorbic acid (above), garlic, spices (middle), curing salt (below)


Step 1: Mincing of meat and fat (3 mm grinder disc)


Step 2: Dry-chopping of lean meat, curing salt and phosphates


Step 3: Ice is added to the dry-chopped lean meat


Step 4: Fat is added to the lean batter


Step 5: The mixture is finely chopped until +12°C is reached

Fig. 168: Production steps for raw-cooked products with coarse meat ingredients


Meat and spices for coarse sausage type


Step 1: Mincing of meats to be added to finely chopped batter for coarse sausage


Step 2: Coarse material is added to finely chopped batter (above). Final mixture after a few rounds in the bowl cutter (below)


Step 3: Coarse sausage (final product). Coarse particles embedded in finely chopped basic matrix

Fig. 169: Production flow for finely chopped batter


*These substances are useful but optional ingredients. They are not absolutely necessary, but widely used.
** The separate production steps indicated are recommended for small-scale operations where highly efficient bowl cutters may not be available. In industrial processing with modern equipment, "dry comminuting" is not needed. Comminuting can be started with lean meat and approximately 2/3 of the ice, the rest of the ice is added together with the fat in order to achieve an additional cooling effect.

Filling the product mixture into casings or other containers

The product mixture is usually filled into casings (Fig. 170, 172) or other containers (Fig. 413, 415). Casings can be natural or made of different materials and are available in different shapes and calibres. Most casings require pre-treatment before being used (see chapter “Casings” page 249).


Fig. 170: Filling of product mixture into a long strand of natural hog casings


Fig. 171: Sausages (linked and twisted to size) are put on a stick for smoking


Fig. 172: Product is filled into an individual casing of larger calibre


Fig. 173: The sausage end is sealed using a metal clip

The product mixture can be manually filled into casings using a simple funnel (Fig. 412), but even in small-scale meat processing operations simple filling machines (piston stuffers, see page 22, 306) are commonly used. Before and during filling the following aspects are of specific importance:

Sausages of smaller calibres are filled into longer strands of natural (mostly sheep) or collagen casings. These strands are divided into portions by manually or mechanically1 twisting (Fig. 171) or tying with a string (Fig. 320). Sausages of bigger calibres are stuffed into individually cut casings. Both ends are tied with a string or sealed with a metal clip (Fig. 173).


1) Modern filling machines have automatic portioning devices to be adjusted for portioning individual sausages in the desired length.

Using the filling machine, portions of the product mixture can also be filled in cans and glass jars. Meat loaf moulds are usually filled by hand.

The period between producing the batter and filling it into casings, cans, moulds etc. should be kept as short as possible. In the batter, even under relatively low temperatures, acid producing microorganisms can develop. The result is the lowering of the pH and reduction of the water binding capacity (WBC) in the batter.

Methods of heat treatment

In order to achieve

Raw-cooked products undergo specific heat treatments as the final processing step, which vary according to the type of products. The most complex heat treatment is applied to sausages. For sausages, after filling in casings, a combination of heat treatments, usually carried out in three steps (reddening, smoking, cooking) is applied. In most small and medium scale operations simple individual machinery (smoke house, cooking vat) suffices. In larger operations more sophisticated equipment (computerized smoking/cooking chambers) is used.

The following describes a typical procedure for sausages undergoing all three steps using simple equipment:

Reddening: After filling, the sausages are hung on sticks in a way that they do not touch each other, thus allowing for air circulation around the individual pieces. The sticks are transferred to the pre-heated smokehouse and exposed to modest heat treatment (hot air) in a first phase without smoke at approximately +50°C. At this temperature the curing process in the product mixture is accelerated and completed (visible as a change in colour from grey to red, see Fig 42 and 70) within a relatively short time depending on the calibre of the sausages (from 15 minutes for calibre 22 to one hour for calibre 90). The presence of cure accelerators (ascorbic acid, sodium ascorbate) in the batter enhances this curing reaction.



Fig. 174: All sausages are spread on a stick allowing smoke to circulate around each individual piece


Fig. 175: Fully loaded smokehouse


Fig. 176: After smoking is completed the sausages must have a uniform attractive colour


Fig. 178: Immersion cooling: The smoked and cooked products are cooled down in cold water


Fig. 177: Cooking process of raw-cooked sausages

Note: Many raw-cooked sausage products undergo hot smoking after the reddening phase (see page 41), where the curing reaction is completed. When raw-cooked products are not smoked, sufficient temperature and time must be provided for the reddening. For sausages in impermeable casings of coated cellulose or synthetic materials or meat loaves in moulds, good reddening results are achieved when sausages or meat loaves are stored for 1-2 hours after filling at ambient temperatures. During this phase the curing process is initiated and will be completed during the heating up in the subsequent cooking process in hot water. If a smoking/cooking chamber is used, reddening is done under controlled conditions at +45-50°C for 30 to 45 minutes before cooking.

Note: For the vast majority of raw-cooked sausages nitrite curing salt is used to achieve an appealing red cured meat colour. Some local specialities are fabricated with common salt only and consequently display a greyish colour (Fig. 179, 180). One example is the “white sausage”. “White products” are normally consumed fresh right after production and are not subjected to reddening or smoking.


Fig. 179: Meat loaf left: with nitrite curing salt
Meat loaf right: with common salt only


Fig. 180: White sausages:
Left: after stuffing (raw meat mix)
Right: after cooking (greyish), ready for consumption

Hot-smoking: After the sausages to be smoked have gone through reddening and developed a red curing colour, the process of hot smoking is initiated. In small and medium scale operations sawdust and open gas flames or electrical heating are used to generate the smoke. Besides these simple smoking facilities, more advanced methods are also available (see page 24, 41, Fig. 174, 175, 176).

The sawdust should originate from untreated wood (preferably hard wood) and must be free of any impurities. Care must be taken that the smoke is developed through smouldering. Open flames must be avoided. Raw-cooked sausages are hot-smoked at temperatures of +65 to 70°C until a desired product colour is achieved (30-60 minutes). As the smoking is carried out at relatively high temperatures, it can be considered part of the overall heat treatment of the product.

Note: The main purpose of sausage smoking is to provide a smoke flavour colour. The aspect of product preservation is only secondary. Smoking with gaseous smoke is only applicable, when sausages are filled in smoke-permeable casings (natural, cellulose or collagen casings). In some advanced smoking/cooking chambers “smoking” can also be carried out by spraying liquid smoke particles onto the product during cooking.

Alternatively, raw-cooked sausage products in smoke impermeable casings can also be produced with smoke flavour. In this case liquid smoke flavour is added to the batter during chopping to achieve the desired flavour (see page 42).

Cooking: After the hot-smoking is completed or for un-smoked products after the reddening phase was initiated, the sausages are taken for further heat treatment (“cooking”, “scalding”) in order to achieve complete protein coagulation. In small and medium scale operations the sausages are transferred to a cooking vat and submerged in hot water of +74° to +80°C for a certain period of time (see table 8, Fig. 115, 177) until a core temperature of at least +72°C is achieved. As a rule of thumb for products exposed to moist heat, 1 minute of heat treatment at +70°C per 1 mm of sausage diameter is required (e.g. cal. 60 needs 60 min.).

During the cooking process all products must be covered by hot water to avoid discolouration and partial undercooking. A floating grill can be used. When a smoking/cooking chamber is used, the sausages remain in the chamber after smoking and cooking is done by applying steam or water vapour saturated hot air1. Cooking is essential and indispensable for all raw-cooked meat products to build up a strong complete network of coagulated protein (see page 129) and make the products “elastic”. It also reduces the bacterial load (see page 95) present in the raw batter. The following facts are important to note:


1) Steam can either be injected into the chamber from an outside source (steam generator) or can be produced inside the chamber. In this case water is introduced into a container inside the chamber and heated up.


Note: It must be kept in mind that even after intensive cooking such sausages are only germ-reduced but not germ-free. They must always be stored refrigerated (£4°C).

Table 8: Parameter for reddening, smoking and cooking

Reddening

Smoking

Cooking

Humidity

Temperature

Period

Humidity

Temperature

Period

Humidity

Temperature

Period

Frankfurter type sausages

20/22mm

60%

45-50°C

30 min

80%

65-70°C

30-45 min

100%

74-80°C

10 min

Smoked sausages

32-40 mm

60%

45-50°C

45 min

80%

65-70°C

45-60 min

100%

74-80°C

30 min

Smoked sausage of Bologna/Lyoner type 70-90 mm

60%

45-50°C

60 min

80%

65-70°C

45-60 min

100%

74-80°C

60 min

Meat loaf (2 kg loaf)

(baking in oven)

--

ambient

1 - 2 hours

--

--

--

--

150°C

180 min

In addition to moderately heated raw-cooked products, some of this group are also suitable for sterilization in hermetically sealed containers. These products can be stored without refrigeration. For more details see page 277.

Cooling of cooked products

After sufficient heat treatment was applied to the sausages to achieve the desired texture, colour and flavour, care must be taken to quickly reduce the product temperature through cooling. Products should never be kept or stored in the temperature range of +20°C to +40° (see Fig. 164) as this would stimulate the growth of remaining bacteria/spores. The rapid cooling is practically achieved by immersing the products in a container of cold water (Fig. 181) or in modern cooking chambers by showering with cold water (Fig. 182). After dropping the product temperature and superficial drying of the sausage surfaces, the products must be immediately transferred into chillers where they can be stored for a few days to a few weeks depending on the type of product (see page 87, 93).


Fig. 181: Immersion cooling (ice water)


Fig. 182: Shower cooling

Mode of consumption

Raw-cooked sausages of smaller diameters such as frankfurters, hotdogs or Viennas are mainly consumed hot. They are heated up immediately before consumption. These small calibre sausages are mostly filled in edible casings (natural casings derived from sheep or collagen casings, page 245) and the edible casings are consumed as part of the product.

Larger calibre sausages are mainly eaten cold on sandwiches. The casings are removed and the sausage is cut into thin slices.

Raw-cooked products others than sausages

Apart from using casings the batter can also be filled into containers such as tin cans or glass jars for subsequent sterilization, resulting in canned products of the raw-cooked type (for more details see chapter on “Canning” page 277). The use of special moulds (Fig. 415) is also common for baking in ovens or in hot air. Such finished products are called meat loaves (Fig. 117, 118, 119, 179). The batter can also be shaped as meat balls (Fig. 237), which are directly submerged into hot water. Meat balls are popular as ingredients for soups.

Theory of formation of “raw-cooked” meat mixes

The main components of meat mixes for raw-cooked meat products are animal protein, animal fat and water. For raw-cooked meat mixes it is essential that fat and water components are evenly dispersed as tiny droplets and are kept stabilized in a finely comminuted protein mass (“protein matrix”) (Fig. 162, 163). Keeping the fat and water droplets “stabilized” in the protein matrix means to prevent their confluescence to larger drops. In order to achieve this target, specific conditions must be met with regard to raw material selection (see page 131), comminuting equipment and techniques (see page 20, 30, 299) and mix temperatures not to exceed during comminuting (see page 136).

Through the comminuting process, the tiny lengthy structures of the muscle fibers (identical with "muscle cells", see Fig. 1) are cut into a multitude of small fragments (Fig. 160). As a result the three types of proteins present in the muscle tissue are set free (Fig. 161). These are

  • connective tissue proteins, mostly collagen, deriving from cell membranes and intercellular tissue,
  • water-soluble soft sarcoplasmatic proteins from inside the muscle cells,
  • myofibrillar proteins, which are solid protein chains (responsible for muscle contraction) inside the muscle cells composed of actin and myosin proteins.

Myofibrillar (actin and myosin) proteins play a decisive role in formation of raw-cooked meat mixes. Extracted from the muscle cells by comminuting the muscle tissue, these proteins are capable of absorbing water and swelling in volume. Myofibrillar proteins are “salt-soluble”, which means that in the presence of salt (NaCl) and water, they can be transferred from the solid to a gelatinous or liquid phase. This does not mean that all myofibrillar proteins present in the mixture are subject to gelation or are fully solubilized. The degree of gelation or solubilization depends on the amount of salt available, intensity of comminuting, pH of the meat and the processing temperature (see page 128, 129). Hence the mix contains different structural phases of myofibrillar proteins:

  • one fraction are muscle cell fragments with unchanged solid myofibrillar proteins,
  • other myofibrillar proteins are swollen through uptake of water and
  • a substantial part of the myofibrillar proteins become gelatinous once fully solubilized through the impact of salt and water.

This situation indicates that raw-cooked meat mixes are not true emulsions, although products of this group are sometimes described as “emulsion-type sausages”. The mixture of protein, fat and water is better characterized by the term “batter” rather than “emulsion”.



Fig. 183: Close-up view of a homogeneous meat mixture (“batter”)


Fig. 184: Microscopic view of a meat mixture. Protein structure network (light green) surrounding enclosures of fat and water (light blue). Also visible are connective tissue particles (dark green)

The batter achieved by comminuting is defined as an aqueous protein phase (“matrix”), where small fat globules are dispersed. The fat globules are immobilized in the matrix and their convalescence prevented by two mechanisms:

  • Liquid myofibrillar proteins, through physical forces, have the tendency of surrounding (“coating”) the fat globules with a protein film and stabilize them.
  • The fat globules are entrapped and immobilized in the viscous protein matrix. During heat treatment the solid or viscous fat globules become liquid. The fat globules are held in place by the protein matrix, which during the same heating process, changes from viscous to solid, the protein structures become denaturated or coagulated. As a result, the fat globules are held finely dispersed and their convalescence is prevented in the generated rigid protein network.

The water is held in the protein matrix as a result of the comminution process either

  • firmly bound to proteins or
  • similar as in the case of the fat globules, entrapped and kept in its place upon protein denaturation in the rigid protein network structure.

The muscle meat used as raw material plays an important role in the water-holding capacity of the batter. Water retention is significantly influenced by the pH-value of the lean meat (see page 4, 131). The higher the pH, the stronger the water retention (see page 7). Natural phosphates (ATP) present in muscle meat during a certain period after slaughter (see page 135) or synthetic phosphates added during batter fabrication (see page 69) have the effect of splitting the acto-myosin complex, which contributes to a significant increase of the water holding capacity of the myofibrillar proteins.

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