Effect of soy protein isolates obtained by weak-base synchronized membrane separation on nanoemulsion stability: A...

Efficient extraction of soy protein isolate (SPI) with high functionalities from soybean meal is essential for developing stable emulsion formulations. This study compared the effects of three extraction methods on protein yield and the stability of nanoemulsions prepared by the obtained soy protein isolate (SPI). We found that the protein recovery of the weak-base synchronized membrane separation (MS) extraction (53 %) was much higher than that of alkali extraction/isoelectric point precipitation (AE, 38 %) and salt extraction (SE, 27 %). During the storage stage (15 days at 55 °C), MS-SPI-stabilized nanoemulsions showed better physicochemical stability (e.g. particle size ∼285 nm, turbiscan stability index∼4.1) than AE-SPI- and SE-SPI-stabilized nanoemulsions, and comparable stability to commercial sodium caseinate. This was further verified by cryo-SEM/TEM, as MS-SPI had more tightly and uniformly distributed particles at the oil-water interface, facilitating the formation of a solid-like interfacial film. Therefore, MS-SPI is a highly stable emulsifier for developing nanoemulsion-based food.