The effect of sprouting of soybean and preparing soymilk and tofu on the yield, nutritional quality, anti-nutritional profile, colour attributes, organoleptic quality and texture profile (tofu) of four commonly used varieties of India were studied to assess the feasibility of using sprouting as a non-chemical, non-thermal tool to improve quality of soy products. Soymilk was prepared from sprouted and unsprouted seeds with process parameters of 121 °C for 25 min. Coagulation of soymilk was done with 3% CaSO4 at 80 °C. Products from sprouted varieties showed an increase in protein (fb) of 7% in milk and 13% in tofu across varieties; a reduction in fat (fb) of 24% in milk and 12% in tofu; in trypsin inhibitor (db) of 73% in milk and 81% in tofu; in phytic acid (db) of 59% in milk and 56% in tofu across varieties. Tofu from sprouted seeds had higher protein and whiteness index but tofu strength was around 43% lesser than its unsprouted counterpart. Taste acceptability showed an increase of 10% and 6.3%; flavour of 23.2% and 11.6% and overall acceptability of 9.9% and 4.4% in milk and in tofu respectively from sprouted varieties. The improvements in composition and quality parameters was seen in all the varieties tested showing that sprouting could be beneficial for product development across varieties. The time and temperature used for production of soymilk was conventional (121 °C for 25 min). Evaluation of time and/temperature reductions could be tried out to reduce the heat requirement and intensity, which could result in better nutritional and functional quality products.
Keywords: Nutrients; Organoleptic quality; Phytic acid; Soymilk; Sprouting; Texture; Tofu; Trypsin inhibitor.