Research Progress on the Effects of Parameters of Alkali Extraction and Acid Precipitation on the Denaturation, Aggregation, and Rheological Characteristics of Soybean Protein Isolate

pH, NaCl and temperature are important process parameters for the manufacturing of soybean protein isolate (SPI). pH and NaCl affect protein aggregation by modifying the surface charge and electrostatic repulsion, whereas temperature affects protein aggregation by changing the surface hydrophobicity and/or disulfide bonding, which in turn changes the particle size and compactness and then the rheology and downstream application characteristics of SPI. This paper reviews the effects and possible mechanisms of pH, NaCl, and temperature on the denaturation, aggregation, and rheological properties of SPI and its components glycinin and β-conglycinin with respect to interaction, thermal stability, degree of aggregation, and gelling properties. The relationship between the degree of protein aggregation, gel strand thickness, gel strand curvature and gel network continuity and gel strength is discussed, and the differences among the effects of pH, NaCl and temperature on protein aggregation are summarized for the purpose of providing an assistance in regulating the degree of SPI aggregation by preparation parameters.