Effect of Protein Type on the Stability of Soyasaponin-Soybean Protein Water-in-Oil-in-Water Type Emulsion

In the present study, a water-in-oil-in-water (W/O/W) multiple emulsion was prepared with soyasaponin as an ingredient of the inner water phase (W₁), soybean protein as an ingredient of the outer water phase (W₂), and corn oil as the oil phase (O) via a two-step emulsification method. The effects of three different types of soybean protein: soybean protein isolate (SPI), 7S and 11S proteins on the overall stability, particle size characteristics, potential characteristics, microstructure, rheological properties, interfacial tension and long-term stability of the emulsion were investigated. Results indicated that the turbiscan stability index (TSI) value of the emulsion showed an upward trend over time and the particle size was concentrated around 6 μm. The absolute potential of the SPI-stabilized emulsion was the highest (-30.2 mV). The system exhibited pseudo-plastic shear thinning behavior, and had the highest viscosity (0.029 Pa·s). After 15 days of storage, all emulsions showed a creaming phenomenon, and the TSI of the SPI-stabilized emulsion was the smallest (21.51). The stability of the 1% SPI-stability emulsion was better than that of the emulsion stabilized with 1% 11S or 7S.