Effect of interactions between glycosylated protein and tannic acid on the physicochemical stability of Pickering emulsions

This study focused on the covalent/noncovalent interaction between glycosylated whey protein isolate (gWPI) and tannic acid (TA) in stabilizing Pickering emulsions. The binary complex of gWPI was fabricated by protein and carbohydrate through the Maillard reaction, the interaction type of the covalent bond between the gWPI and TA was successfully prepared via an alkaline method to form the protein–carbohydrate–polyphenol ternary complex. Fluorescence spectrum results proved that the covalent bond between whey protein isolate (WPI)/gWPI and TA was stronger than the noncovalent bond. The covalent combination of TA strongly affected the fluorescence quenching of WPI and gWPI. Fourier transform infrared spectroscopy showed that the combination of the WPI/gWPI and TA led to changes in the secondary structure of the protein, the covalent interaction between them caused hydrogen bonds and C–O and C–N stretching vibrations. The covalent interaction in ternary complex between gWPI and TA reduced the particle size of Pickering emulsions and improved the thermal, salt ion, and storage stabilities of Pickering emulsions.