Abstract:To investigate the application of whey peptides as antioxidants in food，whey proteins were subjected to enzymolysis to obtain whey peptides.Molecular weight distribution，ultraviolet full wavelength scanning，and circular dichroism spectroscopy were used to examine structural changes in whey peptides following digestion in simulated gastrointestinal fluid；the DPPH free radical scavenging rate，ABTS＋free radical scavenging rate，ferric ion reducing antioxidant power（FRAP），and oxygen radical absorbance capacity（ORAC）of whey peptides were compared before and after digestion.The results showed that the whey peptides consisted of small peptides with molecular weights of 150 Da-1 000 Da accounting for at least 80%of the total molecular weight.Ultraviolet full wavelength scanning showed that electronic transition of aromatic heterocyclic amino acids in the whey peptides changed following digestion，while circular dichroism spectroscopy demonstrated that the whey peptides were stable to pepsin and trypsin.Additionally，except the DPPH radical scavenging rate，the other three antioxidant activity indexes were found to increase，as observed in the simulated gastrointestinal digestion fluid，with a significant increase seen in the ORAC value（p＜0.05）.