Homogeneity and Microstructure of Tofu Depends on 11S/7S Globulin Ratio in Soymilk and Coagulant Concentration

Abstract

The relationship between the coagulant concentration and soybean protein composition for the finer structure of tofu was investigated using its textural and microstructure data. The textural property of tofu with different ratios of 11S/7S globulin was measured at various concentrations of coagulant, and the tofu structure was observed by scanning electron microscopy. The tofu microstructure had the finest network near its change point of breaking stress (CaSO₄) or breaking strain (glucono-δ-lactone). Thus, the coagulant concentration for obtaining a finer tofu network is important for tofu preparation. At concentrations below and above the optimal coagulant concentration, the tofu network consisted of large cell-like units, while at the optimal concentration it consisted of small, uniform units. The structural change point of tofu rich in 11S globulin was at lower coagulant concentrations (0.15~0.2%) and that rich in 7S was at higher coagulant concentrations (0.3~0.4%)