Complexation of resveratrol with soy protein and its improvement on oxidative stability of corn oil/water emulsions

•The water solubility of RES was enhanced by complexation with SPI.•Heat treatment favoured the formation and antioxidant activity of SPI–RES complex.•The emulsions stabilized by SPI–RES complex showed an improved oxidative stability.•The improving effect could be mainly due to the accumulation of RES at the interface. This work was to evaluate the potential of soy protein isolate (SPI)–resveratrol (RES) complex as an emulsifier to improve the effectiveness of RES as a natural antioxidant in corn oil-in-water emulsions. The physical properties and oxidative stability of emulsions stabilized by the native SPI–RES and heated SPI–RES complexes were evaluated. The water solubility of RES was enhanced by complexation with SPI, which was mainly driven by hydrophobic interactions. Heat treatment favoured the formation of the SPI–RES complex and endowed it with a higher antioxidant activity. Furthermore, the emulsions stabilized by the SPI–RES complexes showed an increased oxidative stability with reduced lipid hydroperoxides and volatile hexanal. This improving effect could be attributed to the targeted accumulation of RES at the oil–water interface accompanied by the adsorption of SPI, as evidenced by the high interfacial RES concentration. These findings show that the soy protein–polyphenol complex exhibited a good potential to act as an efficient emulsifier to improve the oxidative stability of emulsions.