Studies on Coagulation Process of Soymilk in Tofu and Kori-tofu Manufacture. Part V. Contribution of Chemical Constituents in Soymilk to the Optimum Concentration of Coagulant in Coagulation Process of Soymilk.

Abstract

This study was conducted to investigate the effects of chemical constituents in soymilk on the value of MVT (time for maximum viscosity) obtained from the torque measurement of coagulating soymilk with Brabender Viscograph. (1) A series of soymilk were prepared from each of 19 varieties of soybeans in order to know a relationship between the chemical constituents and the MVT value. (2) In model coagulation systems using a water extract of defatted soybean meal as well as adid-precipitated protein solution, the effects of concentration of protein and lipids and pH on MVT, MV (maximum viscosity) and FV (flat viscosity) were examined. Dialysis of the water extract of defatted soybean meal reduced MVT. On the contrary, addition of whey to the acid precipitated protein solution increased MVT. These results suggested that 65% of coagulant was consumed by protein fraction and 35% by whey fraction in coagulation process of soymilk. (3) MVT measurements as well as the chemical analyses were done using the whey dialyzed through membranes having molecular weight cut off 100-1 000 daltons. It was revealed that the coagulant-consuming substances in the whey fraction were such substances of 300 to 1 000 daltons that were assumed to be citric acid, phosphorus compounds, peptides, or their complexes.