NEUTRAL AND ALKALINE MUSCLE PROTEASES OF MARINE FISH AND INVERTEBRATES - A REVIEW

Muscle proteases active at neutral and alkaline pH's include calcium-a ctivated neutral proteases, heat-activated thiol proteases, serine pro teases, and metalloproteases. They participate to different extents in postmortem degradation of fish muscle myofibrillar and scaffold prote ins. Their activity in fish muscle is varied and depends on location i n the muscle, the life cycle of the fish, the presence of endogenous a ctivators and inhibitors, pH, and temperature. Recent studies indicate that neutral and alkaline proteases have more impact on the postmorte m deterioration in quality of fish muscles than the cathepsins active at acid pH. Significant quality losses are caused by enzymatic collage n degradation in raw tissues and by heat-activated enzymes in fish gel s.