Abstract:Antioxidant peptides from sheep bone were prepared by enzymatic method, and the amino acids compositions of peptides were analyzed. On the basis of single factor test, the extraction conditions of antioxidant peptides from sheep bone were optimized using response surface methodology. At the same time, peptides with different retention molecular weights were isolated by ultrafiltration, and their antioxidant activity and amino acids compositions were detected. Salicylic acid method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and deoxidization Fe3+ method were applied to investigate the antioxidant activity of peptides with gradient molecular weights and their amino acid compositions were also analyzed. The results showed that the optimum enzyme for enzymatic hydrolysis of sheep bone was alkaline protease, and the optimum process for polypeptide preparation was as follows: pH was 8.9, the amount of enzyme added was 6 400 U/g, hydrolysis duration was 3.25 h, substance mass fraction was 8.8% and the hydrolysis temperature was 50 ℃. The ·OH scavenging activity, DPPH· scavenging activity and the reducing power of the optimal hydrolysis products were (91.31±0.48)%, (32.00±0.12)% and (0.085±0.003), respectively. Components ⅠMr≤3 000), Ⅱ(3 000<Mr≤10 000) and Ⅲ(Mr>10 000) obtained through ultrafiltration had antioxidant capacity. In addition, component Ⅰ(Mr≤3 000) had the highest antioxidant activity, in which the essential and hydrophobic amino acids accounted for 30.41% and 43.13% of the total amino acids, respectively. The antioxidant peptides from sheep bone can be explored as a potential natural antioxidant.
