Bioprocessing Of Meat

Meat has been consumed as part of man's diet since prehistoric times and is an excellent source of high-quality protein and various micronutrients. In spite of religious taboos and socio-economic constraints, it still finds a prime place in the diet of over 70 percent of Indians. Most of the meat produced in India is for domestic consumption, and only a small part is exported. 

1.0Purpose Of Meat processing

The purposes of meat processing are changing from time to time. Originally, meat processing aimed to improve shelf life, flavour and nutritional value. Then, the emphasis shifted to modifying or upgrading the less desirable meat cuts to desirable products. The processing of meat into meat products is advantageous for the following reasons: 

• The addition of different ingredients to meat improves taste and flavour. 
• Specific processing conditions and ingredients improve shelf life. 
• Processed products are convenient to handle and eat. 
• Processing improves nutritive value. 
• Products with specific requirements can be prepared for children, old age, or people who are obese. 
• Processing adds value to meat. 
• Low-value meat cuts can be better utilized in processed products.
• Edible meat byproducts can be effectively utilized in the processed products. 
• Processing improves the demand and marketability of meat. 
• Meat protein can be provided to consumers at an affordable price. 
• The processing industry creates employment. 

2.0Primary Factors In Meat Processing

When we process meat to make products, the following factors are to be considered:

• Cohesion: The product should retain its physical integrity after processing. 
• Fat: Like water, the maximum amount of natural and added fat should be retained during processing till consumption.  
• Moisture: Maximum amount of natural moisture (water) of meat and added water should be retained during processing. This is very important for the yield and quality of the product.
• pH: The pH of meat governs its functional properties, which is very important for product preparation. 
• Protein: Protein quality is essential, particularly in emulsion-type meat products. 
• WHC: The water-holding capacity of meat is important in getting good quality meat products.

3.0 Classification Of Ingredients And Meat Products

We can classify the ingredients into meat-based and non-meat-based ingredients. Meat products can be classified into different categories mainly based on chunk/ particle size, extent of comminution or method of processing, 

(A) Classification according to Chunk particle size 

• Whole muscle - chunk size > 2 to 3 cm,' e.g., ham. 
• Comminuted - chunk size c2 to 3 cm3, e.g., reformed hams, ground meat patties. 
• Emulsion - fine, pasty, homogeneous mixture, e.g., sausages, patties. 

(B) Classification according to the degree of comminution (i.e., the extent of division of meat into meat pieces or particles) 

• None, e.g., ham, bacon 
• Some, e.g., reformed ham, restructured products 
• Coarse, e.g., meatballs, ground meat patties iv. Fine, e.g., sausages 

(C) Classification according to the type of processing 

• Cured meat products 
• Smoked meat products 
• Restructured meat products 
• Fermented meat products 
• Enrobed meat products 
• Intermediate moisture meat products 
• Canned meat products. 

4.0Basic Processing- Procedure

1. Comminution 

• Comminution is the first step for the production of comminuted meat products. The process of comminution reduces the particle size of the meat cuts. The degree of comminution (or particle size) depends upon the type of the processed products. Meat may be coarsely chopped or finely ground. It is often a unique characteristic of a particular product. 
• Comminution improves the uniformity of the product and increases tenderness by reducing the particle size. Meat grinder mincer, silent cutter, emulsion mills and flaking machines are commonly used for comminution. For sausage type products, grinders are usually employed as the first step in the comminution and for non emulsified sausages, grinding is often the only form of comminution. 

2. Emulsification

• An emulsion is a stable mixture of two immiscible substances. Emulsion-type meat products are the most popular processed meat products. When lean muscle tissue, fat, water and salt are mixed together and subjected to high-speed cutting and mixing action, a batter is formed. This batter is called Emulsion. 
• In Emulsion, lean meat and other ingredients like free fat and added water form a matrix. Thus, fat and water do not separate during cooking. Therefore, an emulsion is a mixture of two immiscible liquids, where one liquid is dispersed as tiny droplets or globules within the other. The liquid forming the small droplets is known as the dispersed phase, while the liquid in which these droplets are dispersed is called the continuous phase.

Purposes of preparation of emulsion

• Meat from spent animals can be effectively utilized for the preparation of Emulsion. 
• During mincing and chopping, muscle and connective tissue fibres are broken, making meat tissue tender. 
• Emulsion prevents moisture and fat loss during cooking. 
• This improves the quality of the product, particularly its juiciness, texture, flavour, and cooking yield. 
• The batter prepared can be transformed into a variety of products of different tastes, shapes and characteristics. 
• Including several edible emulsion-based meat byproducts can increase the volume of products; unlike other meat products, low-value meat products can be prepared with non-meat economical ingredients. 

Factors affecting stability of emulsion 

a. Temperature during emulsification

• Emulsion temperature increases during chopping and emulsification due to friction in the chopper. 
• Increasing temperature helps release soluble protein, accelerates cured colour development and improves flavour characteristics. 
• However, too high a temperature adversely affects the emulsion stability by denaturing the soluble proteins and melting fat particles. 
• The final emulsion temperature must be within 20-25°C. 
• Adding ice rather than water to the meat ingredients can control or reduce the temperature. General Principles of Processing of Meat during Chopping and Emulsification. 

b. Fat particle size

• Meat fat must be subdivided into smaller particles until an emulsion is formed. 
• With the reduction in particle size of the fat, total surface area of the fat particles proportionately increases. 
• This increase in surface area requires much more soluble protein to completely coat the surface of the smaller particles. 
• Thus the over chopping of meat fat can result in a large surface area 'which can not be coated by available soluble proteins to adequately stabilize the emulsion. 

c. pH

• The solubility of the protein depends upon the pH of the medium. 
• More protein is extracted as the pH of muscle increases. 
• Thus, higher pH values result in nom-stable emulsions. 
• The amount of fat emulsified per protein unit is called emulsification capacity. 
• The amount of protein extracted is affected by several factors. 

d. Amount and Type of soluble protein

• Pre-rigour meat is superior in emulsion stability to post-rigour meat, as 50 per cent more salt-soluble proteins can be extracted in the pre-rigour stage. 
• Myofibrillar proteins are salt soluble and superior to sarcoplasmic proteins as emulsifying agents. 
• Therefore, more fat can be emulsified with the protein extracted from pre-rigour meat than with the same amount extracted post-rigour. 
• Emulsion stability increases as the amount of soluble protein available to act as an emulsifying agent increases. 

3. Formulation 

• Formulation is the mixing of different ingredients, such as meat, curing mixtures, seasonings, binders, fillers, and water, to produce processed meat products of uniform appearance, composition, taste, and physical properties from batch to batch and from time to time. 
• Formulation is also important from the point of view of maintaining the quality standards of the meat products, which should be kept while using the least expensive raw materials.

4. Enrobing

• Enrobing is the coating of a product's surface with edible materials. Enrobed fish and chicken parts are also popular in certain parts of our country. 
• Nowadays, different types of meats and kat products are coated to provide a wide range of meat products. 
• In addition to raw or cured chunks, restructured or emulsion-based products can also be enrobed to further improve their sensory qualities and shelf life. Enrobed products are also called battered and breaded products. Thus, the process can be called battering and breading. 
• Some of the examples of enrobed products are: 
• Bone in product, e.g., chicken drumsticks, chicken cut-up parts. 
• Whole muscle or meat chunks e.g., breast filets of chicken, chunks of pork, mutton and buffalo meat. 
• Ground meat products, e.g., enrobed nuggets and enrobed patties. 

5. Canning 

In canning, meat or meat products are treated with heat to kill spoilage microorganisms. The heat treatment is generally given after packing the products in cans or retort pouches. The machine used for heat treatment is called a retort. The heat treatment is scheduled so that it either commercially sterilizes the product, i.e., destroys all viable microorganisms, or pasteurized the product, i.e., destroys most of the organisms.

6. Fermentation  

Fermented meat products are prepared by microbial fermentation and dehydration to develop specific flavour and texture. In the production of fermented meat products, we add selected bacterial cultures to the minced meat. These are called 'starter cultures'. Starter cultures are available commercially and contain microorganisms like Lactobacillus, Pediococcus, Lactococcus, and Micrococcus.

7. Restructuring

• Restructured technology is also a popular processing technology for preparation of different meat products. Restructured meat products are generally prepared from less expensive cuts, tough cuts, meat trimmings or combination of these. 
• In this technology, small pieces of meat or meat trimmings are joined together to form bigger pieces. The bigger pieces can then be cut into smaller pieces. 
• Thus, we can get meat pieces and products of desirable shapes and sizes. Using different additives improves sensory qualities during the process of binding small pieces.

8. Cooking Meat  Processing

• Probably, meat cooking had occurred for the first time accidentally when fresh meat was exposed to heat or fire. Now it has been modernized and sophisticated. 
• Cooking improves the eating and keeping qualities of the meat product and provides a variety of meat products.

Effects of cooking on meat products

• Meat proteins are coagulated and denatured by cooking. 
• The solubility of the meat protein changes the colour of the product. Cooking improves meat palatability by intensifying the flavour and altering the product's texture. 
• Cooking increases the storage life of meat products due to the destruction of a considerable number of microorganisms and reduced water content. 
• The texture and tenderness of the meat products are modified by cooking. 
• The red colour of CUM meat products is stabilized by cooking. 
• Development of off-flavor in the meat products can be prevented by inactivation of the indigenous proteolytic enzymes through the process of cooking.

5.0Hurdle Technology 

• This is also known as "combination preservation". In the combination preservation process, several hurdles are used to prevent the growth of microorganisms. 
• The & includes pH decrease, use of preservatives, lowering water activity by applying different principles simultaneously, use of heat, storage at low temperature, etc. 
• By using hurdle technology, the quality of the product is not affected, and at the same time, the product's shelf life is greatly improved. 
• Intermediate moisture meat products are also prepared using hurdle technology.

Intermediate Moisture Meat (IMM) 

• These products can be defined as partially dehydrated products with a suitable concentration of dissolved solids. 
• The dissolved solids bind the remaining water sufficiently to inhibit the growth of bacteria, molds, and yeasts. Thus, the intermediate moisture products are characterized by low water activity (water available for the growth of bacteria). 
• Typical intermediate-moisture foods have water activities ranging from 0.6 to 0.85 and a moisture content of 30 to 50%. 
• The IMM products are generally shelf-stable without refrigeration or thermal processing. Due to these properties, JMM products are important in defense services. 
• However, due to lower moisture content, some people do not like the texture of IMM products.

Development of IlM Products 

• Development of IMM products generally consists of the following principles: 
• They lower water activity by adding solutes/additives such as glycerol, sucrose, glucose and salt. 
• Humectants are additives used to lower water activity. These substances bind with water and make it unavailable for bacteria. 
• Retarding microbial growth by the addition of antimicrobial agents such as propylene glycol and sorbic acid. 
• Heat treatment to inactivate enzymes.