ENZYMATIC HYDROLYSIS OF PROTEIN FROM SMALL YELLOW CROAKER (PSENDOSCIAENA POLYACTIS) AND EVALUATION OF ITS ANTIOXIDANT ACTIVITY

Abstract

ABSTRACT Enzymatic hydrolysis of protein from small yellow croaker (Pseudosciaena polyactis) was investigated. Three commercial food grade proteases were used to hydrolyze the small yellow croaker. Among the three hydrolysates, papain hydrolysate exerted the highest scavenging activity against a,a-diphenyl-b-picrylhydrazyl (DPPH) for use in the small yellow croaker hydrolysis. The optimum parameters for hydrolysis using papain were established by the single-factor and orthogonal test. The optimal hydrolysis conditions were as follows: temperature of 60C, hydrolysis time of 4 h, enzyme concentration of 0.2% and meal/water ratio of 1:5. Under these conditions, the highest degree of hydrolysis (DH) was 49.50%. Antioxidants of protein hydrolysates at 40.96, 43.75, 48.85 and 49.50% of DH were further investigated by DPPH and hydroxyl radical-scavenging activity. There is a linear parallel relationship between the DHs and the antioxidant properties, and the DH at 49.50% possessed the highest antioxidant activity. The enzymatic hydrolysis of protein from small yellow croaker could be used to produce the hydrolysates possessing antioxidative activities. PRACTICAL APPLICATIONS Small yellow croaker (Pseudosciaena polyactis), with high production in China, is still underutilized despite the fact that it is rich in high quality protein. Fish protein hydrolysates have been shown to have potential for nutritional or pharmaceutical applications. The aims of this study were to prepare peptides from small yellow croaker (P. polyactis) by enzymatic hydrolysis and to evaluate the antioxidant activity of the resulting hydrolysate. The hydrolysis of protein with proteolytic enzymes can provide more marketable and value-added food ingredients or industrial products.