Impact of heating treatments on physical stability and lipid-protein co-oxidation in oil-in-water emulsion prepared with soy protein isolates

The physical stability and lipid-protein co-oxidation of oil-in-water emulsions stabilized by heat-modified soy protein isolates (SPI) during storage were investigated. Heat treatments of SPI decreased the emulsion's ζ-potential absolute value but improved its physical stability during storage via decreasing particle size of oil droplet and increasing the percentage of adsorbed protein on the interface film; the higher heating temperature had a positive correlation with emulsion's physical stability. Moreover, native SPI-stabilized emulsion displayed lower hydroperoxide content during storage; nevertheless, it had the highest hexanal content. Lipid and protein co-oxidation was observed in SPI-stabilized emulsions and influenced by the partition of SPI. The emulsions prepared with heat-modified SPI (90 and 120 °C), exhibited higher values of maximum emission wavelength in fluorescence spectroscopy, whereas they had lower N′-formyl-l-kynurenine, carbonyl, and Schiff base level. Therefore, the heating of SPI is promising for the design of emulsion with improved physical and chemical stability.