Process Optimization for Soft Tofu

Response surface methodology (RSM) was used to determine the optimum combinations of four factors, solids content of soy milk (10–14 °Brix), concentration of coagulant (0.25–0.41%, W/V), mixing temperature (75–91°C) and stirring time (5–25 sec) for producing soft tofu on a small pilot scale. Neither brittleness nor elasticity of the top part of tofu were influenced significantly by any factors. Yield was affected (p < 0.05) by soymilk solids content and coagulant concentration. Solids and protein content of tofu were affected (p < 0.05) by 3 factors except mixing temperature. Solids content of soy milk was the most important factor affecting texture. Optimum combinations were soymilk solids 11.8 to 12.3 °Brix, coagulant 0.27 to 0.32%, mixing temperatures 85 to 91°C, and stirring times 5 to 11.3 sec.