Enhanced acidic stability of O/W emulsions by synergistic interactions between okara protein and carboxymethyl cellulose

Abstract

The application of okara protein (OP) in emulsions is yet to be fully explored. The present work aims to investigate the effects of carboxymethyl cellulose (CMC) - OP complexes on the emulsion properties and emulsion stability. CMC (0–5 g/kg) was introduced to electrostatically interact with the OP (10 g/kg) at pH 4.0, and then O/W emulsions (1:9, g/g) were prepared by the complexes and systematically characterized. As the CMC concentration increased from 0 to 5 g/kg, the particle size of the OP-CMC complexes decreased from 6400 to 380 nm, while the ζ-potential decreased from 1 to −28 mV. As for the emulsions, their ζ-potential was reduced from −1 to −28 mV while their droplet size decreased from 201 to 10 μm with less flocculation. The surface protein content decreased from 97% to 73% while less creaming was observed in the fresh emulsions. The results obtained in the present work demonstrated that the negatively charged OP-CMC complexes pre-formed by electrostatic interaction contributed to an improved O/W emulsion stability at pH 4.0. The results obtained may be conducive to the potential utilization of OP-based dairy products, especially in an acid environment.