Hydrolysis kinetics and antioxidant activity of collagen under simulated gastrointestinal digestion

The hydrolysis kinetics and antioxidant activity of collagen from Nile tilapia were investigated under simulated gastrointestinal digestion in this study. From gastric to intestinal phase, degree of hydrolysis increased from 1.15% to 16.74%, while surface hydrophobicity decreased from 21.46% to 2.06%; DPPH radical scavenging increased from 18.22% to 31.79%, but inhibition rate of linoleic acid peroxidation reached 34.63% in 40 min and then kept stability. After digestion, the collagen hydrolysates were separated into three fractions by ultrafiltration. The fraction (86.70%) with average molecular weight of 436.80 Da exhibited the highest antioxidant activity, suggesting the high digestibility and bioactivity of collagen. The fraction was further purified with multi-step chromatography and identified to be Gly-Pro-Met (303.38 Da) by UPLC-ESI-MS with IC50 value being 25.64 µg/mL for DPPH radical. These results may help better understanding its physiological effects and utilize it in foods and pharmaceuticals.