Proteases and meat tenderization

Tenderness in one of the most important aspects of meat quality particularly for beef, lamb and pork. Aging at refrigerated temperatures allows proteases within the muscle to break up the structure of the myofibrils and tenderises the meat. Calpain 1, a calcium-dependent cysteine protease, is the key enzyme involved and it is activity is regulated by a specific inhibitor, calpastatin. Aging is a complex process and involves other proteases including caspases, cathepsins and calpain 2 and 3. The activity of all of these is modulated by the physical conditions and other proteins within the muscle. Aging does not lead to proteolysis of the connective tissue, which is responsible for the background toughness of different muscles, and exogenous proteases such as papain and actinidin are needed to hydrolyze collagen