Abstract: In this study, heated and native whey protein were separately employed as emulsifiers to prepare oil-in-water (O/W) emulsions using a high-pressure homogenizer. Luteolin at different concentrations (0.00, 0.05, 0.10, 0.20 and 0.40 mg/mL) were added to the emulsions to form whey protein-luteolin complex. Fluorescence spectra, dynamic light scattering spectra, and the contents of protein and luteolin at the interface were determined in order to evaluate the potential influence of the complex as a natural antioxidant on the physical and chemical stability of emulsions. The formation of whey protein-luteolin complex was verified by analysis of fluorescence spectra and fluorescence quenching occurred. Based on the peroxide value (POV) and thiobarbituric acid reactive substance (TBARS) value, whey protein-luteolin complex significantly improved the oxidative stability (P < 0.05), but had no significant effect on the physical stability of emulsions (P > 0.05). The heating treatment could improve the adsorption of luteolin but blocked protein at the interface. However, luteolin content had no significant effect on the adsorption of protein (P > 0.05).

Key words: emulsion, whey protein, luteolin, physical stability, oxidative stability