Physicochemical and functional properties of Chinese jujube (Ziziphus jujube mill.) seeds protein concentrate

Abstract

About 8 million tons of jujube pomace arise within a year in China. Bioconversion of food processing residues is receiving increased attention because these residual materials represent a possible and utilizable resource for conversion into useful products. To explore the application of Chinese jujube (Ziziphus jujube Mill.) seeds protein concentrate (ZPI) in food industry, its physiochemical and functional properties were analyzed in this study. The free sulfhydryl content of ZPI is 7.1 × 10 -6 mol/g of protein at pH 8.0. Differential scanning calorimetry analyses showed that ZPI had only one endothermic peak with denaturation temperature of about 91°C. Amino acid analyses revealed that ZPI exhibited high levels of glutamic acid, aspartic acid and arginine. The least gelation concentration (LGC) of ZPI is ∼8% at pH 7.0, whereas the protein solubility, emulsifying activity, emulsion stability, and waterholding capacity of ZPI were much lower than those of soybean protein concentrate (SPI). These results suggest that ZPI could be used as a valuable source of protein and gel.