Abstract:

The releases of free amino acids and peptides during the enzymatic hydrolysis of chicken protein by Alcalase were investigated by high-performance liquid chromatography,and the scavenging activities of the resulted hy drolysates on hydroxyl and superoxide free radicals were analyzed by phenanthroline-Fe reaction system and pyrogallol autoxidation.The results are stated below:(1)the contents of soluble protein and free amino acids gradually increase during the enzymatic hydrolysis,(2)the sum total of peptides increases in the first 16 h and decreases thereafter,(3)the dissolving of insoluble chicken protein and the degrading of peptides with the relative molecular mass(RMM)more than 10000 nearly end up"after 4 h,(4)the percentage of peptides with the RMM between 5000 and 10000 greatly increases in the first 4 h,then decreases in the next 4 h.till an unnoticeable fluctuation (P>0.1),(5)the percentage of peptides with the RMM between 3 000 and 5 000 nearly keeps unchanged during the enzymatic hydrolysis(P>0+1),and(6)the percentage of peptides with the RMM less than 3 000 obviously increases in the first 8 h,and then remains constant(P>0.1).Moreover,the unhydrolyzed sample and the hy.drolysates of chicken with various hydrolysis time exhibit noticeable scavenging activities on hydroxyl and superoxide flee radicals,and the activity of the form er is stronger,which is related to the compositions of peptide and amino acid in the hydrolysates.

Key words: chicken protein, enzymatic hydrolysis, scavenging activity on free radical, free amino acid, peptide