Effect of calcium sulfate concentration in soymilk on the microstructure of firm tofu and the protein constitutions in tofu whey

The effects of calcium sulfate concentration in soymilk on the microstructure of tofu and the constitutions of protein in tofu whey were investigated. The firm tofu made with 0.4% CaSO(4)(.)2H(2)O was found to be most uniform and continuous in the microstructure. This tofu gave the maximal tofu yield, maximal solid and protein recoveries, and the best water retention ability. The results of gel electrophoresis and the ratio of amino nitrogen to total organic nitrogen indicated that the low molecular weight proteins in tofu whey were at their lowest when the tofu was made with 0.4% CaSO(4)(.)2H(2)O. The SEM observations suggested that the tofu made with 0.4% CaSO(4)(.)2H(2)O has the most uniform and homogeneous microstructure and, consequently, can most efficiently retain soybean proteins and water in the tofu gel.