Research on the phosphorylation of soy protein isolate with sodium tripoly phosphate

Soy protein isolates(SPI) were phosphorylated with sodium tripoly phosphate (STP) by various concentrations of SPI and STP, pHs and reacting time at room temperature. The degrees of phosphorylation and the best conditions of phosphorylation—4% of SPI, 9% of STP, pH = 9.0 and 3 h were determined. The functional properties of native and modified proteins (aqueous solubility, emulsification properties and viscosity) were also determined. At the given ranges of pH, the solubility and the viscosity did not change remarkably (p > 0.05), while the emulsifying properties increased significantly (p < 0.05) after SPI was phosphorylated.