Mechanism of physical modification of insoluble soy protein concentrate

The mechanism for solubilization of alcohol-leached soy protein concentrate (ALSPC) by physical modification was studied from the standpoint of molecular interactions, which are related to the differences in protein solubility under different conditions. The low solubility of ALSPC is caused by both noncovalent and covalent forces, but the noncovalent forces do not affect the solubility of modified soy protein concentrate (MSPC). Gel filtration shows that the major constituents of soluble protein from ALSPC and MSPC are protein molecules and protein aggregates, respectively. Physical modification promotes the formation of aggregates that are readily soluble in buffer. Fluorescence spectroscopy further proved that the hydrophobic groups are located in the interior of the aggregates. The reason for the formation of soluble protein aggregates during physical modification of ALSPC is discussed.