Calpain, meat

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. 

Gault, N. F. S. Stmctural aspects of raw meat. In The chemistry of muscle-based foods (Eds. D.E. Johnston, M.K. Knight, D.A. Ledward) Royal Society of Chemistry, Cambridge, 1992, pp. 79 Geesink, G.H., Kuchay, S. Chrishti, A.H., Koohmaraie, M. p-Calpain is essential for postmortem proteolysis of muscle proteins. J. Anim. Sci. 84, 2834 (2(X)6) Giddings, G.G. The basis of color in muscle foods. 

From these results, it might be concluded that both m- and m-calpains and cathepsins B and L are responsible for the increase in peptides concentrations at the ultimate pH (5.5-5.8) during postmortem aging of meat. 

It might be concluded that the increase in firee amino acids in meats during postmortem aging was mainly caused by the action of aminopeptidases C, H and P on the peptides, which are produced from meat proteins by the action of cathepsins and calpains (Figure 6). 

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