Abstract
The freshness of skipjack meat rapidly deteriorates, and skipjack cured in mugi-miso is therefore popularly used in Kyushu in order to preserve the quality and retain the taste. In this study, a chemical analysis of protein was conducted on skipjack meat cured in miso (called misodzuke skipjack) and on miso itself. The degradation of several proteins in the misodzuke skipjack and the elution of some proteins from misodzuke skipjack into miso were observed by SDS-PAGE. Most of the free amino acid contents in misodzuke skipjack increased during the curing period. It was also found that aspartic protease and serine protease were present in miso by measuring the protease activity and the effect of protein inhibitors. Although protease activity was not detected in skipjack meat that had not been cured in miso, protease activity at optimal pH 7 was detected in misodzuke skipjack meat. Misodzuke skipjack cured for 10 days demonstrated a maximum protease activity which was inhibited by the serine protease inhibitor, AEBSF.
