Study on the interaction mechanism, physicochemical properties and application in oil-in-water emulsion of soy protein isolate and tannic acid

The combination of plant protein and polyphenol compounds is an effective strategy to improve the ability of this protein stabilized emulsion. However, the influence of interaction between protein and polyphenol complex on the emulsion was unclear. Therefore, this study took soy protein isolate (SPI) and tannic acid (TA) as the research object, systematically studied the interaction mechanism, physicochemical properties and application in O/W emulsion. The results showed that the main non-covalent interaction was hydrogen bond and van der Waals force of SPI-TA. The addition of TA changed the secondary structure and reduced the surface hydrophobicity of SPI. In terms of functional properties, TA improved the emulsifying ability and reduced the interfacial tension of SPI. In addition, SPI-TA complex, as a complex emulsifier, could form a stable emulsion, which inhibited the speed and extent of oil oxidation and lipid digestion. Our research results could provide some help for the elaboration of the interaction mechanism of SPI-TA and the preparation of antioxidant emulsions.