Analysis of Initial Aggregates of Soymilk Proteins Produced Under Different Coagulation Rate Conditions with Magnesium Chloride Addition

The composition of the aggregates formed during the initial stages of tofu coagulation under different coagulation rates was investigated. To analyze the composition of the initial aggregates, we established fractionation conditions based on particle size. Sodium dodecyl-sulfate-polyacrylamide gel electrophoresis showed that with increasing rates of MgCl2 concentration, the ratio of basic subunits and oleosins in the initial aggregates increased, whereas that of α + α′ subunits decreased. The adsorption of the soluble protein (α + α′ subunits) is presumed to suppress the aggregation of the hydrophobic parts of the protein particles comprising mainly the basic subunit. The slow rate of increase in MgCl2 concentration and formation of initial aggregates with fewer protein particles and oil bodies efficiently built highly uniform networks. This finding contributes to the development of processing technology and the expansion of diversity of newly processed tofu foods by controlling the coagulation rate.