In vitro gastrointestinal digestion of purified bovine kappa-casein variants A, B, and E: Effects on antioxidant and angiotensin 1-converting enzyme inhibitory capacity

The κ-CN genetic variants A, B, and E were purified from milk from homozygous cows, using isoelectric precipitation followed by calcium precipitation and ion-exchange chromatography. The purified κ-CN variants displayed varying degrees of glycosylation, and were furthermore differentially affected by in vitro gastrointestinal digestion. Both antioxidant and angiotensin 1-converting enzyme inhibitory capacity were significantly increased by digestion, with the antioxidant capacity of the E variant being significantly lower (p < 0.05) than that of the A and B variants. These results suggest that genetic polymophisms in bovine milk protein coding genes may be of significance for nutritional and health-related endpoints.