Extracellular Proteases of Contaminant Bacteria in Fish Spoilage: A Review

Although the bacteriology of fish spoilage has been the subject of a number of reviews, the role of bacterial protease secretion in relation to fish spoilage has not received enough attention. This article attempts to focus the proteolytic activities of contaminant microorganisms in fish, the role of muscle constituents on protease synthesis, involvement of extracellular proteases in bacterial penetration of the muscle, and action of the enzymes on fish muscle proteins. The limitation of conventional chilling in completely controlling the bacterial spoilage has been stressed since the proteases secreted by psychrotrophic organisms can act on the fish muscle even at low temperatures. The article advocates employment of stringent measures to control secretion and activities of bacterial extracellular proteases to prolong the keeping qualities of refrigerated fish.