Enhancing stability and performance of emulsion stabilized by soy protein isolate nanofiber - polysaccharide complexes

Soy protein isolate can self-assemble into nanofibers, thereby improving their performance as emulsifiers. However, the lack of stability in extreme environments (especially acidic conditions) limits their use in certain foods. In this study, three polysaccharides (sodium alginate (SA), xanthan gum (XG) and arabic gum (AG)) were used to improve the stability of soy protein isolate nanofiber (SPIF) emulsions. Complexes exhibit high ζ-potential. Electrostatic force was the major interaction that maintained the internal structure of complexes. The addition of SA can effectively reduce the interfacial tension and present higher contact angle. The emulsification properties of SPIF-SA emulsions were higher than those of SPIF-AG and SPIF-XG emulsions at pH 3 and 60% of the oil phase, which proved by the decreased particle size, increased ζ-potential, and uniform droplet distribution. Polysaccharides improved the interface properties based on electrostatic force, which increased the emulsion stability of nanofibers. The results contribute to expanding the possibility of SPIF-polysaccharide complexes becoming a new emulsifier in the food industry.