Research Progress on Polyphenol Regulation of Lipid-Protein Co-oxidation in Emulsions Stabilized by Proteins, Polysaccharides or Their Complexes

Emulsions stabilized by natural biocompatible polymers, such as proteins and polysaccharides, have become increasingly prevalent in the food industry. However, lipid and protein oxidation inevitably occur in emulsions during storage, which have a significantly negative impact on the application of emulsions in the food industry. Polyphenols, as natural antioxidants, can bind to proteins and polysaccharides and regulate the oxidative stability of emulsions stabilized by proteins, polysaccharides or their complexes by altering the structure, interfacial properties, and antioxidant activity of proteins and polysaccharides. Furthermore, polyphenols, owing to their robust ability to scavenge free radicals, reduce metal ions, and promote the formation of interfacial barriers by emulsion stabilizers, represent a highly cost-effective option for enhancing the lifetime and quality of food emulsions stabilized by natural biocompatible polymers. Nevertheless, few studies have elaborated on the mechanism of the impact of polyphenols on the oxidative stability of emulsions stabilized by proteins, polysaccharides or their complexes. On this ground, this article first describes the co-oxidation mechanism of lipids and proteins in food emulsions and summarizes the interaction of polyphenols with proteins, polysaccharides and their complexes. Next, the impacts of types and amounts of polyphenols on the structures, interfacial properties, and antioxidant activities of polyphenol-protein/polysaccharide and polyphenol-protein-polysaccharide complexes are analyzed. Finally, the effects and underlying mechanisms of polyphenols on the oxidative stability of protein, polysaccharide or protein-polysaccharide stabilized emulsions are discussed. The findings of this review provide a theoretical basis for improving the application of food emulsions in the food industry.