Improvement of protein emulsion stability through glycosylated black bean protein covalent interaction with (-)-epigallocatechin-3-gallate

This study investigated the effects of covalent conjugates combined by glycosylated black bean protein isolate (BBPI-G) and (-)-epigallocatechin-3-gallate (EGCG) on the emulsion stability. Fourier transform infrared (FTIR) spectroscopy showed that covalent binding of EGCG with BBPI-G made the protein molecule unfolded. Besides, the emulsifying properties of BBPI-G were increased after combined with EGCG. BBPI-G-EGCG emulsion had lower mean particle size and higher content of interfacial protein adsorption (AP), which resulted in thicker and more impact oil-water interface. Therefore, the stability of emulsions was significantly improved. Furthermore, the emulsions prepared by BBPI-G-EGCG compounds exhibited considerable stability in storage, oxidation, thermal treatments, freeze-thaw and freeze-dried powders resolubility. This study demonstrated that the covalent bond of glycosylated protein and polyphenols could advance the emulsifying performance of protein, and BBPI-G-EGCG covalent complex was an effective emulsifier for preparing high stability emulsions.