Proteomic profiling of the coagulation of soymilk proteins induced by magnesium chloride

The coagulation of soymilk proteins induced by magnesium chloride at 30 degrees C was investigated using the SDS-PAGE and two-dimensional electrophoresis. Approximately 88.4% of the soymilk proteins were coagulated into the soymilk pellet fraction (SPF) by 5 mM magnesium chloride, and the total protein in the soymilk supernatant fraction (SSF) decreased from 7.80 + 0.12 mg mL(-1) to 0.90 + 0.18 mg mL(-1). SDS-PAGE showed that the total intensities of the protein bands corresponding to the 7S alpha' subunit, the 7S alpha subunit, the 7S beta subunit and the 11S A3 subunit were decreased to 10.5 +/- 0.3%, 11.8 +/- 1.1%, 6.6 +/- 0.2% and 15.1 +/- 2.2%, respectively. Two-dimensional electrophoresis indicated that most of the soymilk proteins in the SSF, including the 7S subunits, 11S subunits, beta-amylase, sucrose binding protein 2, Bd 30K, lectin and trypsin inhibitor A, were coagulated into the SPF by 5 mM magnesium chloride. (C) 2012 Elsevier Ltd. All rights reserved.