This research used soybean from Canada as raw material and focusing on two major categories: (1)Effects of different soaking, grinding temperature and heating methods on soy milk protein and soy milk quality; (2)Effects of different soaking, grinding temperature and different heating methods on tofu texture.
Results showed: (1)Using different grinding temperature (5℃、30℃、60℃、80℃), as grinding temperature increased, the soymilk would become more yellowish and greenish. At lower grinding temperature, the soymilk viscosity, color brightness, and white index were higher. The protein surface hydrophobicity increased as the grinding temperature increased. The soaking temperature at 5℃ had higher protein surface hydrophobicity than at 30℃. Two-step heating had higher protein surface hydrophobicity than one-step heating.
Using SDS-PAGE electrophoresis pattern analysis, as the grinding temperature increased, the amount of β-conglycin subunit would increase. But the acidic and basic subunit of Glycinin and the ratio of 11S/7S would decrease. (2) Using different heating, soaking and grinding condition, the syneresis rate increased as grinding temperature increase. Soaking temperature at 30 ℃ or two-step heating had higher syneresis rate than soaking at 5 ℃ or one-step heating in respect. Two-step heating had higher density than one-step heating. Using lower soaking and grinding temperature and two-step heating would increase the tofu hardness, gumminess, adhesiveness, springiness, chewiness and cohesiveness. The results of this experiment could be used to improve the tofu quality for soy processing manufacturer.
