Changes of in vitro digestion rate and antioxidant activity of digestion products of ethanol-modified whey protein isolates

Effects of ethanol treatment at different concentrations (20%, 40%, 60%, and 80%, v/v) on in vitro digestion rate and antioxidant activity of digestion products of whey protein isolates (WPI) were investigated. The results indicated that treatment with an intermediate concentration of ethanol (40%, v/v) produced the highest WPI digestion rate and the strongest antioxidant activities of its digestion products (P < 0.05), which was further verified by the results of microstructure, particle size and amino acid profiles of the digestion products. However, larger aggregates induced by higher ethanol concentrations (60 or 80%, v/v) might decrease the susceptibility of protease and subsequently lower the digestibility of WPI. The results suggested that a moderate concentration of ethanol treatment could be used as a potential way to enhance the in vitro digestion rate of WPI, as well as increase the antioxidant activities of its digestion products.