Abstract: In the present work, alcalase was identified as the most suitable enzyme for enzymatic hydrolysis of Antarctic krill among 7 commonly used enzymes based on simultaneous consideration of chloroacetic acid-nitrogen soluble index (TCA-NSI) and degree of hydrolysis (DH). In order to optimize the hydrolysis of Antarctic krill by alcalase, the effects of the hydrolysis conditions enzyme dosage, substrate concentration, pH, temperature and hydrolysis time on TCA-NSI and DH were studied by one-factor-at-a-time and orthogonal rotary composite design methods. Two regression models with TCA-NSI or DH as a function of each hydrolysis condition were established. The optimal process conditions for hydrolyzing Antarctic krill with alcalase were 50.7 ℃ hydrolysis temperature, pH 8.01, 3010 U/g alcalase dosage and 239 min hydrolysis time. Under the optimal conditions, the TCA-NSI and DH were 73.02% and 42.33%, respectively. Meanwhile, peptides with an average length of 2.36 and a molecular mass of 277.9 were obtained.

Key words: Antarctic krill, alcalase, oligopeptide, hydrolysis degree