Effect of electrochemical modification on the structural characteristics and emulsion storage stability of soy protein isolate

Abstract This study investigated the impact of electrolysis modification on the structural characteristics of SPI and used the prepared novel emulsifier to improve the storage stability of the oil-in-water emulsion. The exposed sulfhydryl group content increased from 12.62 × 10 −5 mol/g in the control to 14.35 × 10 −5 mol/g in the SPI following electrolysis for 120 min. In addition, after electrolysis the secondary structural analysis using Fourier transform infrared spectroscopy (FTIR) indicated that samples showed a decrease in the α-helix proportion, and fluorescence spectra revealed tertiary conformational changes of the SPI. The particle size distributions of the electrolysis-treated protein solutions had monomodal distributions, and the ζ-potential absolute values became larger. The water holding capacity (WHC) and fat holding capacity (FHC) were significantly improved. The peroxide value (POV) of oil in the electrolysis-treated SPI emulsion was 14.59 mmol/kg oil, and the protein carbonyl content was also lower than that in the native protein emulsion after it was stored at 25 °C for 4 weeks. In summary, this study might suggest that an electrochemical reactor could be applied to modify the structural characteristics and functions of proteins in order to obtain the desired products.