Abstract: In this study, we investigated the effect and mechanism of different heat treatments (55, 65, 75, 85 and 95 ℃) on the stability of the emulsion formed during the enzyme-assisted aqueous extraction of soybean oil. The ζ-potential and particle size distribution were measured, and microscopic observation, sodium dodecyl sulfate gel electrophoresis, infrared and fluorescence spectroscopic characterization were carried out. It was found that as the temperature increased, the ζ-potential and particle size of the emulsion increased significantly, and the viscosity decreased faster. Upon heating at a low temperature, the subunit distribution of the emulsion protein almost remained unaltered. The molecular mass of the subunit initially increased followed by a more significant increase when the heating temperature was increased to 85 ℃, and then to 95 ℃. After heating, α-helix content decreased while random coil content increased; the higher the heating temperature, the more significant the change. The fluorescence intensity of the protein decreased and fluorescence quenching was observed with increasing temperature.

Key words: enzyme-assisted aqueous extraction, emulsion, heat treatment, fluorescence spectroscopy, stability