Effect of Soy Protein Isolate-Sucrose Ester on the Stability of Emulsion Prepared by Different Oil

In order to explore the effect of compound emulsifiers on the emulsification of different oils, soybean protein isolate (SPI) and sucrose ester (SE) were used as composite emulsifier, and lard (LA), soybean oil (SO), linseed oil (LO), fish oil (FO) as oil phase to prepare the emulsions (E). The stability differences of emulsions prepared with various oil phases were studied by measuring the emulsifying activity, structure properties, thermal characteristics and emulsifying stability. The results showed that the emulsifying activity index of E_LA was the highest (27.374 m²/g, 361.243 min) among the four emulsions, and its average droplet size (D) was the smallest (8.411±0.670 μm)_. Microstructure images revealed that the particle uniformity was followed by E_LA>E_SO>E_LO>E_FO. DSC results showed that E_LA took the most melting energy (ΔH=−57.67±1.28 J/g), while the enthalpy of E_FO was only −10.18±0.10 J/g. The data of storage and oxidation stability displayed that E_LA was the most stable. The difference of unsaturated fatty acid in oil affected the stability of emulsion, the larger the proportion of unsaturated fatty acid and the higher the degree of unsaturation in oil phase, accounting for the worse the stability of emulsion. These results could enrich the research of SPI-SE in oil emulsification, and will benefit development of application on oil emulsification.