Conjugation with gum acacia improved the ability of whey protein isolate-(-)-epigallocatechin-3-gallate covalent complexes to stabilize β-carotene emulsions.

A ternary covalent complex was prepared by conjugating whey protein isolate (WPI)-(-)-epigallocatechin-3-gallate (EGCG) covalent complex with gum acacia (GA). A blue shift in the amide A band and decreased intensity of amide bands in the Fourier transform infrared spectroscopy spectra, and an increase in molecular size confirmed the covalent linkage. It was utilized to stabilize β-carotene emulsion. The freeze-thaw, ionic strength, thermal and pH stability of emulsions were enhanced by conjugation with GA. Compared with WPI, the WPI-EGCG covalent complex and its mixture with GA, the ternary covalent complex used as an emulsifier more effectively inhibited the degradation of encapsulated β-carotene under ultraviolet light irradiation and thermal treatment. The stability of the emulsion during simulated gastrointestinal digestion and the in vitro bioaccessibility of BC also significantly (p < 0.05) increased after conjugation with GA. These findings could provide insights into the design of promising and effective food-grade emulsion delivery systems.