Contribution of muscle proteinases to meat tenderization.

The exact mechanisms involved in the postmortem meat tenderization process and the nature of changes associated with improvement in tenderness are complex and not fully understood. Based on the relevant evidence thus far obtained, the focus of this review is on clarifying the factors affecting meat tenderness, particularly the toughening and tenderness phases, possible endogenous proteinases involved in meat tenderization and how these proteinases contribute to meat tenderization. Of the different biochemical and ultrastructural changes occurring in the meat tenderization process, myofibril disruption at the Z-disk and contractile proteins are discussed in detail. This myofibril disruption can perhaps be ascribed to the synergistic action of calcium-dependent proteinases (both mu- and m-calpains) and lysosomal proteinases, especially the cathepsins B and L.