Current understanding on the role of proteolysis on meat quality

Meat tenderness is improved in the aging process through disruption of muscle structures by endogenous proteolytic systems. Postmortem molecular changes in the muscle activate proteases and cause degradation of key myofibrillar and cytoskeletal proteins. Several proteolytic systems exhibit activity, and especially the calpain system has been implicated in the tenderization process. This review discusses the role and contribution to postmortem proteolysis of the calpain system, the caspases, the proteasome, and the lysosomal cathepsins. The focus is on the changes in the myofibrils and the associated cytoskeleton, but also a view of the effect of matrix metalloproteases in the extracellular matrix is presented.