The purification and identification of antioxidants and dipeptidyl peptidase IV inhibitory peptides from whey protein hydrolysates

In the present study, whey protein was enzymatically hydrolyzed using an ultrahigh-pressure synergistic enzymolysis method. The antioxidant activities and DPP-IV inhibitory activities of the enzymatic hydrolysates were measured. Three-layer isolation and purification were conducted on the enzymatic hydrolysates with antioxidant activity and DPP-IV inhibitory activity by gel filtration chromatography and RP-HPLC. The amino acid sequences were determined by LC-MS/MS. The identified amino acid sequences were then synthesized, and their antioxidants and DPP-IV inhibitory activities were determined. The results showed that 3 of the 14 polypeptides of N3-8 exhibited high antioxidant activity. Among them, peptide DDQNPHSSN had both high antioxidant activity and DPP-IV inhibitory activity. When the concentration was 1 mg/mL, then the ABTS radical scavenging rate, DPPH radical scavenging rate and reducing power were prominent, reaching 91.42%, 88.76%, and 0.637%, respectively, and DPP-IV inhibitory activity reached 66.28%. Whey protease hydrolysates are expected to be commercially developed as functional peptides.