Changes in protease activity during fermentation of fish sauce and the correlation with antioxidant activity.

BACKGROUND Antioxidant activity has been found in fermented fish sauce. In this experiment, the properties of endogenous protease and antioxidant activity were studied in anchovy sauce during fermentation. Moreover, the correlation between protease activity and antioxidant activity in fermented anchovy sauce was analyzed by partial least squares (PLS). RESULTS The results showed that at least four proteases were present in the endogenous enzyme solution, and the optimum pH values were 2.5, 5.5, 9.0, and 12.5, respectively. The maximum inhibition rate of endogenous protease from high to low was: serine protease inhibitor > trypsin inhibitor > aspartic protease inhibitor (pepsin inhibitor) > cysteine protease inhibitor > metalloprotease inhibitor. At the 6th month of fermentation, fish sauce had stronger trypsin, pepsin-like activity and antioxidant activity. At the 9th month of fermentation, the cathepsin activity was greater. A model correlating changes in protease activity with antioxidant activity suggested that the trypsin and serine protease were the main factors affecting antioxidant activity. CONCLUSION A model correlating changes in protease activity with antioxidant activity of fish sauce has been reported. This study has laid a foundation for further exploration of the formation of antioxidant substances and antioxidant effects during the process of fish sauce fermentation. This article is protected by copyright. All rights reserved.