Abstract:Soy protein isolate (SPI) was subjected to shear and heat treatment under acidic conditions (pH 3.0, 3.4 and 3.8), and protein particles distributed from 2 to 100 μm were obtained. As prepared at pH condition was more close to the isoelectric point of SPI, the resulting particles had a higher degree of microparticulation and a better stability. For the soy protein particles prepared at pH 3.8, their internal protein content was 34.22%, and their protein leakage did not exceed 13% within the range of pH 2.0 to 8.0. The change of pH and re-heat treatment (95 ℃ for 30 min) had little effects on their particle size and morphology. Compared to SPI dispersion, the viscosity of soy protein particle dispersion decreased significantly after heat treatment. And heat-set gelation did not occur in this dispersion even when the particle concentration was 12%. These protein particles could be used in the high-protein foods such as beverage and yogurt, so as to make them have smooth mouthfeel and fortify their protein content.
