Preparation and stability characterization of soybean protein isolate/sodium alginate complexes-based nanoemulsions using high-pressure homogenization

Effects of sodium alginate (SA) and homogenization on the physicochemical properties of soybean protein isolate (SPI)-based nanoemulsions (NEs) were investigated. Results showed that SPI-based NEs added with 0.02%–0.06% (w/v) SA exhibited lesser mean particle size (<300 nm) and polydispersity index (<0.27), and greater absolute ζ-potential value (>33 mV) than the 0.08% or 0.10% SA-added SPI-based NEs. Moreover, high-pressure homogenization and addition of 0.02%–0.06% (w/v) SA relatively better enhanced SPI-based NEs' thermal stability, and storage stability. According to the changes in ζ-potential value and the characteristic infrared absorption peaks, SA can also combine with positive charges of SPI by electrostatic interactions under neutral conditions. Therefore, the combination of SA addition and homogenization has a potential to be used to stabilize SPI-based NEs, providing a promising method to develop innovative ingredients for the processing of food emulsions or materials for the encapsulation of bioactive compounds.