Effect of different process parameters on the quality of soymilk and tofu from sprouted soybean

Abstract

The effect of grinding cum blanching (GCB) of sprouted soybean at different temperatures on milk and tofu quality was studied. Three temperatures (121 °C-T1,100 °C-T2 and 80 °C-T3) for GCB were used to produce soymilk and tofu from sprouted soybean which were analysed for the yield, nutritional, anti-nutritional profile, colour attributes, particle size, organoleptic quality and texture profile. Unsprouted Soybeans with GCB at 121 °C served as control (C). There was significant difference (P < 0.5) in trypsin inhibitor content in milk and ranged from 4.1 mg/g in T3 to 1.4 mg/g in T1. Optimal reduction in TI of 75–80 % was achieved in T2. There was significant difference (P < 0.5) in protein extractability and ranged from 84.4 % in C to 93.9 % in T2. Hardness (N) of tofu was around 11.22 in C and reduced to 8.9, 8.6 and 4.4 in T1, T2 and T3 respectively. L values of soymilk ranged from 83.4 in C to 85.8 in T3; in tofu from 83.1(T3) to 87.2 (C) and decreased with the increase in heating temperature and time. Particle size d [3, 2] and volume d [4, 3] between treatments varied significantly (P < 0.0001 and P < 0.0038). Overall acceptability scores on 9 point hedonic scale for all treatments for milk and tofu were above 5. The texture scores of tofu for T3 were very low due to its soft structure. From the above investigations 100 °C was the optimal temperature for GCB of sprouted soybean for the production of good quality soymilk and tofu.