Non-covalent interactions between rice protein and three polyphenols and potential application in emulsions

Rice protein (RP) and polyphenols are often used in functional foods. This study investigated the non-covalent interactions between RP and three polyphenols (curcumin, CUR; quercetin, QUE; resveratrol, RES) and used the complexes as emulsifiers to create emulsions. Three polyphenols interacted with RP to varying extents, with QUE showing the greatest binding affinity and inducing the greatest alterations in its secondary structure. Molecular docking analysis elucidated the driving forces between them including hydrophobic interactions, hydrogen bonding, and van der Waals forces. Combination with QUE or RES induced structural changes of RP, increasing particle size of complexes. The synergistic effect of polyphenols and protein also enhanced radical scavenging capacity of complexes. Compared to pure protein, all complexes successfully created emulsions with smaller particle size (378-395 nm vs. 470 nm), higher absolute potential (37.43-38.26 mV vs. 35.62 mV), and greater lipid oxidation stability by altering protein conformation.