Characterization of protease from Aspergillus Oryzae surface culture and application in fish sauce processing

Abstract

Some kinetic parameters of the purified protease from Aspergillus oryzae surface culture were determined: Km=634.5mg/L and Vmax=13.98mg/L.min. Ions Na+, Zn2+ and Fe3+ had an inhibitor effect to the enzyme activity. On the contrary, ion Mg 2+ had an activator effect. The influence of ion Ca2+ to the protease activity was more complicated. With low concentration (0.005M), this ion activated the protease; but with higher concentration (0.01M), it inhibited the enzyme activity. The purified protease was applied in fish sauce processing for proteolysis acceleration. High salt content (25%) in the fish-salt mixture decreased obviously the enzyme activity. Addition of salt and fungal protease to the fish sample with several times accelerated significantly fish proteolysis.