Characterization of protease and effects of temperature and salinity on the biochemical changes during fermentation of Antarctic krill

BACKGROUND Despite their abundance, Antarctic krill are underutilized because of numerous difficulties in their commercial processing. Ideally, fermentation technology can be applied to transform them into a popular condiment. In addition to the exploration of protease properties, the present study aimed to evaluate proteinase activity, pH , amino nitrogen, and histamine formation during fermentation at different temperatures and salt treatments. RESULTS Even though the activity of Antarctic krill protease reached a maximum at 40 °C and pH 7, it was stable at 30 °C and pH 7–9. Among the metal ions tested, Ca 2+ , Mg 2+ and K + increased protease activity, in contrast to Zn 2+ and Cu 2+ . Within each treatment, the highest protease activity and amino nitrogen content, as well as the lowest histamine level, were observed on day 12 of fermentation. Treatment at 35 °C with 180 g kg –1 salt led to the production of maximum amino nitrogen (0.0352 g kg –1 ) and low histamine (≤0.0497 g kg –1 ). CONCLUSION Krill paste fermented for 12 days at 35 °C with 180 g kg –1 salt exhibited the optimal quality and properties, suggesting an efficient method for fermentation of Antarctic krill and other aquatic resources. © 2017 Society of Chemical Industry