Tenderness of meats

Preparation of cheeses and soy derivatives Solubilization of protein concentrates Production of protein hydrolysates Gluten modification in bread doughs Chillproofing of beer Plastein formation Tenderization of meats Quality determination of proteins... 

Gastric or intestinal digestion Cellular protein turnover Post-mortem tenderization of meat Aggregation of polypeptide chains Blood clotting Activation of precursors Complement action Cleavage of presecretory proteins... 

Trypsin Obtained from purified extracts of porcine or bovine pancreas. Produced as white to tan, amorphous powders soluble in water, but practically insoluble in alcohol, in chloroform, and in ether. Major active principle trypsin. Typical applications used in baking, in the tenderizing of meat, and in the production of protein hydrolysates. 

Ficin The purified proteolytic substance derived from the latex of Ficus sp. (Fam. Moraceae), which include a variety of tropical fig trees. Produced as a white to off white powder completely soluble in water. (Liquid fig latex concentrates are light to dark brown.) Major active principle ficin. Typical applications used in the chillproofing of beer, in the tenderizing of meat, and in the conditioning of dough in baking. 

Carbohydrase and Protease, Mixed (Bacillus subtilis var. including Bacillus amyloliquefaciens) Produced as an off white to tan, amorphous powder or as a liquid by controlled fermentation using Bacillus subtilis var. Soluble in water (the solution is usually light yellow to dark brown), but practically insoluble in alcohol, in chloroform, and in ether. Major active principles (1) a-amylase, (2) /3-glucanase, (3) protease, and (4) pentosanase. Typical applications used in the preparation of starch syrups, alcohol, beer, dextrose, bakery products, and fishmeal in the tenderizing of meat and in the preparation of protein hydrolysates. 

Bratzler, L.J. 1932. Measuring the tenderness of meat by means of a mechanical shear. Master s thesis, Kansas State College. 

FIGURE 4-48 Variation of tenderness of meat stored at 2 C with time after slaughter. 

Calcium ion is a known activator of many biochemical processes. The calcium-activated neutral protease (CANP) plays an important role in postmortem tenderizing of meat. The function of the metal ion in such an enzyme is believed to be either neutralization of the charges on the surface, by preventing electrostatic repulsion of subunits, or effecting of a conformational change required for association of the subunits. Thus the metal ions must be present in a specific state to perform this function. 

C. K. Kang and W. D. Warner. Tenderization of meat with papaya latex proteases. J. Food Sci. 39 812 (1974). 

Two enzymatic systems, i.e., calpain and cathepsin influence tenderization of meat. The activity of calpain reduces under high pressure. The activity of p-calpain is also reduced during ageing (Ouali, 1990). Qin et al. (2001) showed that high-pressure treatment (100-300 MPa, 10 min) of beef resulted in a decrease in the total calpain activity however, the acid phosphatase and alkaline phosphatase activities were not significantly reduced. Homma et al. (1995) found that the total activity of calpain in pressurized muscle increased due to a reduction in the level of calpastatin because of its pressure sensitivity this in turn resulted in meat tenderization. 

Of the many functions of proteolytic enzymes listed in Table I, the most extensively used commercially are chillproofing of beer, production of cheese, tenderization of meats, and production of protein hydrolysates. Two of the most active research areas at the moment include use of proteolytic enzymes for plastein formation (see Proteolytic-Induced Aggregation of Proteins, p. 99) and the solubilization of fish protein concentrate. 

Basically, there are three major groups of proteins in muscle tissue (a) the sarcoplasmic proteins of the muscle cell cytoplasm, (b) the myofibrillar proteins, soluble at high ionic strengths, that make up the myofibril or contractile part of the muscle, and (c) the stromal proteins comprised largely of the connective tissue proteins, collagen, and elastin. The myofibrillar proteins and the stromal proteins are fibrous and elongated they form viscous solutions with large shear resistance. These properties coupled with other lines of indirect evidence indicate that the physical properties of the myofibrillar and stromal proteins are directly related to the texture and tenderness of meat (34). 

In general, in beef muscle free catheptic activity reaches its maximum between four and six days postmortem (81, 92). At the same time major textural properties of meat show large changes between four and 13 days postmortem (33). Lysosomal enzymes have been implicated in the tenderization of meats by a number of workers. 

In sensory evaluation consumers estimate fruit firmness on the basis of the deformation resulting from physical pressure applied by the hand and fingers. The toughness or tenderness of meat is subjectively evaluated in terms of the effort required for the teeth to penetrate and masticate the flesh tissues. Therefore, determination of rheological properties of foodstuffs is important in evaluation of consumer-determined quality by correlating rheological measurements with sensory tests. 

Food Cheese manufacture Flour modification Stabilization of emulsions Extraction of fish and vegetable oils Tenderizing of meat Chillproofing of beer... 

---