Abstract

In this study, the effects of temperature, pH, enzyme content, hydrolysis time on antioxidant activity of the hydrolysate from Tra catfish (Pangasiushypophthalmus) by-products with Alcalase® 2.4 L FG were investigated using DPPH• (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method (DPPH• SM) and FRAP (ferric reducing antioxidant potential) method. The chemical composition of the Tra catfish byproducts included 58.5% moisture, 33.88% crude protein, 50.14% crude lipid and 15.83% ash (on dry weight basis). The result of antioxidant activity of the hydrolysate showed that the 50% DPPH• inhibition concentration (IC50) of the hydrolysate reached about 6775 μg/mL which was 1645-fold higher than that of vitamin C and 17-fold higher than that of BHT (Butylated Hydroxytoluene) with the degree of hydrolysis (DH) of the hydrolysate of 14.6% when hydrolysis time was 5h, enzyme/substrate (E/S) ratio was 30 U/g protein, hydrolysis temperature was 550C, and pH was 7.5. The antioxidant potential of hydrolysate using FRAP method reached about 52.12 μMTrolox equivalent which was 53-fold and 18-fold lower than those of vitamin C and BHT, respectively, when the hydrolysis time was 5h, enzyme/substrate ratio was 30 U/g protein, temperature was 500C, and pH level was 8. The result showed that the antioxidant proteolysate derived from Tra catfish by-products has the potential to be used as a natural antioxidant ingredient in nutraceutical and functional food industry.