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Inhibitors that control muscle softening are important for regulating the activities of specific proteinases in meat. Proteolytic activity of endogenous proteinases in postmortem fish leads to the deterioration of myofibres. Calpain proteolytic enzyme system in skeletal muscles is mainly responsible for the post-mortem proteolysis. Soluble sarcoplasmic serine proteinase and the insoluble myofibrillar serine proteinase fractions contribute to the modori effects in surimi gels while myosin heavy chains contribute to gel strength. Proteolytic degenerative processes negatively affect the entire quality spectrum of the fish as food. Legume seeds are a good source of proteinase inhibitors with the potential to emerge as a promising tool in fish meat quality management. Many workers have studied the potent inhibitory effect of the seed flour from various legume crops on the flesh, surimi gels and visceral proteinases of fishes. The present review provides collective information about proteolysis in fish and its control by using legume seed flour as a natural source of proteinase inhibitors. Use of legume seed flour can reduce the dependence of the meat processing industry on the non-renewable synthetic chemical agents. Moreover, the use of natural products from sustainable resources also leads to the improved economics of meat production. [ABSTRACT FROM AUTHOR]

Lizardfish is a major ingredient for the manufacture of surimi in Japan, and its viscera are considered a novel source of protease to enhance protein autolysis. We investigated the non-volatile taste components of fish sauce produced from the lizardfish Saurida wanieso viscera in order to clarify the effects of fermentation conditions on the quality of fish sauce. Samples were fermented for 40 days under three sets of conditions: group 1, pH 7.0 and 60 °C; group 2, pH 11.0 and 40 °C; and group 3, uncontrolled pH and ambient temperature. Group 2 showed the highest concentration of umami amino acids (1,195.29 mg/100 ml) and sweet amino acids (2,033.60 mg/100 ml). High levels of lactic acid (1,219.65 mg/100 ml), acetic acid (367.08 mg/100 ml), and pyroglutamic acid (261.66 mg/100 ml) were also found in group 2. In addition, investigation of nucleic acid-related compounds revealed differences in the degree of nucleotide hydrolysis among the three groups during fermentation. Sensory evaluation showed that group 2 had the highest umami and the lowest bitterness, indicating that this group had the most preferable taste. These results reveal that fermentation under conditions optimal for endogenous proteases is beneficial for producing a product with optimal taste qualities. [ABSTRACT FROM AUTHOR]

To elucidate the role of microbes and endogenous proteases in the formation of the taste-active components during processing of heshiko, a Japanese traditional seafood produced by aging salted mackerel with rice bran, the production of lactic acid, free amino acids, and acid-soluble peptides throughout the aging process was compared in the absence and presence of antibiotics including chloramphenicol, penicillin, and cycloheximide. Although viable counts on fish flesh on a 2.5% NaCl-GYP agar plate increased to 10 cfu/g with the aging process of heshiko in the absence of the antibiotics, adding the antibiotics suppressed the increase in viable counts to less than 10 cfu/g throughout the aging process. Lactic acid barely increased due to the suppression of microbial growth by the antibiotics. In spite of the inhibition of bacterial growth throughout the processing of heshiko upon the addition of the antibiotics, little difference was observed in the production of free amino acids and acid-soluble peptides. These results suggest that, unlike lactic acid (which is a fermentation product of lactic acid bacteria), free amino acids and acid-soluble peptides are mainly produced through protein hydrolysis by endogenous proteases in mackerel meats during the aging process of heshiko. [ABSTRACT FROM AUTHOR]