The properties and utilization of proteases of marine fish and invertebrates

The muscles and internal organs of marine animals contain many proteases. These enzymes fulfill different metabolic functions in the living organisms and affect the sensory quality and functional properties of the catch. Their activity depends on the species, life cycle, and the feeding status of the organism. Many proteases of marine origin differ from their counterparts in terrestrial animals in being more active at lower temperature and less resistant to thermal denaturation. Of practical importance in the industry is their role in ripening of salted fish, fish sauces and marinades, modyfying fish protein concentrates, ensilaging of seafood offal, and deskinning of fishery products. The negative effects comprise mainly the early post morten quality degradation of the catch and deterioration of the rheological properties of fish gels. Proteolytic preparations form different marine sources may be used successfully in food processing and as industrial enzymes, e. g. tanning agents.