Source and changes of proteinase activities of Indian anchovy (Stolephorus spp.) during fish sauce fermentation

Trypsin-like proteinases exhibited the highest activity in viscera and muscle of Indian anchovy (Stolephorus spp.). The molecular weights (MWs) of proteinases in viscera were estimated to be 31, 35, 44, 49 and 57kDa by activity staining in the presence of 4 moI L-1 NaCl. The MW of proteinase extracted from muscle was 56kDa. This reflects that only one proteinase was extracted from muscle whereas five proteinases were extracted from viscera. Trypsin-like, chymotrypsin-like and cathepsin L-like proteinases were found in commercial fish sauce samples throughout 12 months of fermentation, suggesting that these proteinases were stable at high salt concentrations (250-300 g kg(-1) NaCI) and under acidic conditions (pH 5.2-5.8). In contrast, leucine aminopeptidase activity was detected only in the first month. The MWs of proteinases found in fish sauce after various fermentation periods were estimated to be 37, 47 and 53 kDa, which coincided with the MWs of proteinases found in Indian anchovy. (c) 2006 Society of Chemical Industry.