Comparison of Peptide Composition and in Vitro Antioxidant Activity of Different Hydrolysates of Turbot Meat

To investigate the effect of ripening, simulated digestion and enzymatic hydrolysis on the antioxidant ability of turbot hydrolysis, alcalase and simulated digestion were applied to hydrolyze the raw and ripening turbot meat to prepare the raw meat alkaline protease hydrolysate, ripening meat alkaline protease hydrolysate, raw meat simulated digestion product and ripening meat simulated digestion product. The degree of hydrolysis, molecular weight distribution, amino acid composition, peptides composition and in vitro antioxidant activities were compared. The results showed that the degree of hydrolysis of the raw meat alkaline protease hydrolysate was the highest, which was 20.18%. The molecular weight (M_W) distribution of four samples varied greatly, only one peptides were shared, but the amino acid composition presented insignificant difference. The M_W distribution of alcalase hydrolysates were mainly lower than 1000 Da, the 2~4 peptides accounted for 64.57%~51.73% of the detected peptides sequences. While, in the simulated digestion samples, the 1000~3000 Da peptides fraction accounted for over 50%, and dominated by polypeptides (>10 length). Ripening diminished the proportion of small peptides (<6 length). In vitro antioxidant ability assays indicated that alcalase hydrolysates exhibited stronger antioxidant abilities than simulated digestion products, ripening reduced the antioxidant abilities of the raw meat alkaline protease hydrolysate. The raw meat alkaline protease hydrolysate presented the best superoxide anion and hydroxyl radical scavenging ability, as well as the highest ferric reducing ability. Therefore, alcalase is superior to simulated digestion in hydrolyzing turbot meat, ripening will ameliorate the antioxidant ability of turbot meat hydrolysates.