1Course of Food Science and Technology, Tokyo University of Fisheries, Tokyo 108-8477, 2Maruha Corporation Central Research Institute, Ibaraki 300-4295, 3Department of Applied Biology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
The effect of crude protease inhibitors of marine bacterial origin on the formation of gels from various fishes such as krile, sardine and squid meat paste (surimi) was investigated. Among them, crude protease from sardine was strongly inhibited followed by krile whereas no inhibition was observed in squid. Various naturally occurring protease inhibitors were mixed with bacterial ones and the inhibitory effect on the crude protease from sardine was also determined. The most effective one was leupeptin from terrestrial actinomycete. The crude inhibitors of microbial origin were frantionated by DEAE-cellulofine column chromatography, resulting in two active franctions. The fraction eluted first, marinostatin (simple peptide), had an inhibitory activity against serine protease whereas the second one, monastatin (glycoprotein), had an inhibitory activity against cysteine protease. The inhibitory effect of these inhibitors on the formation of gel was performed. The elasticity and jelly strength of gel from sardine surimi was effective in the presence of monastatin whereas no such effect was observed in the presence of marinostatin, suggesting that the former one might be applicable to cooked fish meat gel (Kamaboko).