Endogenous muscle proteases involved in softening mechanisms and release of bioactive peptides during storage of underutilized fish species

Texture is one of the most important quality parameters of fish muscle which impacts consumer’s acceptance, the market value and the suitability of fish for processing and preservation. Textural changes are rapid in fish muscle leading to unfavourable quality changes such as muscle softening and fillet gaping. Rapid softening of flesh may be one of the main reasons for underutilization of a wide range of bycatch and discarded fishery species. High proteolytic activity of endogenous muscle proteases, calpains and cathepsins, induces myofibrillar breakdown involved in softening of fish during post-mortem storage. In addition, post-mortem proteolysis of fish myofibrils by endogenous enzymes releases polypeptides and oligopeptides, some of which may demonstrate potential bioactive properties. The scope of the present research was to determine the major endogenous enzymes active in post-mortem fish muscle and establish their impact on structural softening and the release of bioactive peptides during storage of underutilized fish species