Preparation and Characterization of Pickering Emulsion of Soybean Protein Isolate-Carrageenan-Xanthan Terpolymer

In this study, the Pickering emulsion of soybean protein isolate (SPI)-carrageenan-xanthan terpolymer was prepared. The effects of ratio of SPI to carraneenan-xanthan, pH, mass concentration of carraneenan, mass concentration of xanthan and volume of soybean oil on the particle size, Zeta potential, emulsifying activity index (EAI), emulsifying stability index (ESI) and SPI secondary structure of Pickering emulsion system were all investigated. Besides, the characteristics of emulsion system with different volume of inner phase during storage at normal temperature were studied. The results showed that the stability of Pickering emulsion of SPI-carrageenan-xanthan terpolymer was good, when the mass concentration ratio of SPI to the complex polysaccharide was 1:10, pH was 9.0, the mass concentration of carrageenan and xanthan both were 0.2%, and the oil volume was 10%~85%. Under this conditions, the average particle size of Pickering emulsion of SPI-carrageenan-xanthan terpolymer was 351±24.12 nm, and the absolute value of Zeta potential was 99.4±1.4 mV. As the inner phase volume of soybean oil increased from 10% to 85%, the particles size distribution of Pickering emulsion became more uniform and stable. When the oil volume was 75%, the dispersion state of emulsion particles was the best, EAI and ESI reached the maximum, and α-helix and β-fold contents of SPI were the highest. In addition, the storage experiments at normal temperature showed that the particle size of Pickering emulsion with different volume of inner phase showed an overall increasing trend, and the absolute value of zeta potential, EAI and ESI showed an overall decreasing trend with the storage time extending. The α-helix content and β-angle content of all emulsions decreased, while β-folding increased, and random crimp content did not change significantly. High inner phase emulsions with 75% and 85% inner phase volume showed better stability than those with 10%~50% inner phase volume. In conclusion, this study explored the preparation and characterization of Pickering emulsion of SPI-carrageenan-xanthan terpolymer, aimed to provide technical reference for targeted delivery of functional substances and application innovation of fat substitutes.