Improving the antioxidant activity, in vitro digestibility and reducing the allergenicity of whey protein isolate by glycosylation with short-chain inulin and interaction with cyanidin-3-glucoside

Whey protein isolate (WPI) is particularly constrained in infant formula owing to the widespread food allergy to milk proteins. Thus, inhibiting the allergens in WPI is crucial. This research aimed to explore the influence of the interaction between glycosylated protein [WPI glycosylated with short-chain inulin (SCI)] and cyanidin-3-glucoside (C3G) on antioxidant activity, thermostability, digestibility, and allergenicity of the proteins. The complex prepared by glycosylated WPI and C3G (2:1, w/w, pH 7.4) exhibited the best stability based on particle size and zeta potential. FTIR results showed that the major forces between glycosylated WPI and C3G were hydrogen bonding force, C–N stretching, and N–H bending. The antioxidant activity and thermal stability were as follows: WPI-SCI/C3G > WPI/C3G > WPI-SCI > WPI, indicating that the introduction of C3G and the interaction between glycosylated WPI and C3G can improve the above mentioned properties of the protein. Furthermore, WPI/C3G and WPI-SCI/C3G had higher resistance to pepsin and trypsin, which slowed down the digestion process and effectively delivered bioactive proteins to the distal end of the gastrointestinal tract. Western blot analysis and enzyme-linked immunosorbent assay showed that the IgE contents of WPI, WPI/C3G, WPI-SCI, and WPI-SCI/C3G were 26.99 ± 0.3, 23.65 ± 0.58, 23.07 ± 0.21, and 10.41 ± 0.14 ng/mL respectively, suggesting that the glycosylated modification and the introduction of C3G can significantly reduce the allergenicity of β-lactoglobulin in WPI. This study contributes to the development of a new promising method for reducing the allergenicity of WPI and its application in food industry.