Calpains- and cathepsins-induced myofibrillar changes in post-mortem fish: Impact on structural softening and release of bioactive peptides

Proteolytic activation of endogenous muscle proteases, calpains and cathepsins, contributes to autolysis of fish myofibrils and concomitant softening of fillets during post-mortem storage. Calpains activity causes limited hydrolysis of myofibrils during initial days of post-mortem storage, whereas cathepsins in addition to proteolysis of major myofibrillar and associated proteins have the capacity to breakdown actin and myosin at later stages of post-mortem storage. Proteolysis of fish myofibrils post-mortem releases polypeptides and oligopeptides, some of which may demonstrate potential bioactive properties.