Abstract: Objective:To optimize enzymolysis technology of codfish protein to obtain active peptide and determine antioxidant abilities of the hydrolysate. Methods:Effects of temperature,pH,hydrolysis time and concentration ratio of enzyme to substrate([E]/[S]) on content of peptides from protein hydrolyzed with Alcalase 2.4L were studied. And the optimization of the hydrolysis conditions was made by quadratic rotation design. The antioxidant abilities of the hydrolysate were evaluated by measuring free radicals scavenging ability.Results:The results showed that the optimum conditions of hydrolysis with Alcalase 2.4L are pH 8,ratio of fish flesh to water 1:8(m/V) ,hydrolysis time 3 h and temperature 65 ℃ and [E]/[S] 0.3%. The scavenging rates to hydroxyl radical and superoxide radical of the hydrolysate with degree of hydrolysis 38.46% are 56.34% and 41.56% respectively. Conclusion:The results establish the theory basis for the application of codfish.

Key words: codfish, radicals, hydrolysates, peptide