45G-7 |
Effect of soymilk compositions and process conditions on the optimal concentration of coagulant for making tofu |
Z. S. LIU, Department of Cereal and Food Sciences, North Dakota State University, IACC 322, Fargo, ND 58105 and S. K. C. Chang, Dept. of Cereal Science, North Dakota State Univ., IACC 322, Fargo, 58105-5728. The concentrations of coagulants in soymilk affect profoundly the yield, textural and flavor properties of the resulting tofu. The optimal concentration of coagulant is affected by raw bean characteristics and tofu processing conditions. Our objective was to study the effects of soymilk compositions/properties and soymilk processing conditions on the optimal concentration of coagulant. Thirty-seven soybean materials were tested. CaCl2 and MgCl2 were used as coagulants. The coagulants' optimal concentrations in soymilk were determined using a rapid titration method developed in our lab. Soymilk compositions/properties included protein, ash, Ca, Mg, phytic acid, titratable acidity, pH, solid content and soymilk Brix. Statistical correlations between the optimal concentrations of coagulants and soymilk compositions/properties were analyzed. Soymilk processing conditions such as soybean soaking time, raw soymilk standing time, the sequence of dilution and heating of soymilk, soymilk heating time and heating rate were investigated to study their influences on the optimal concentrations of coagulants. Our results showed that the optimal concentration of the coagulant for tofu making was significantly (p<0.05) correlated with soymilk protein content (-0.52 for CaCl2 and -0.54 for MgCl2), soymilk original calcium content (-0.35 for CaCl2 and -0.43 for MgCl2), soymilk original magnesium content (-0.20 for CaCl2 and -0.22 for MgCl2), soymilk titratable acidity (-0.36 for CaCl2 and -0.29 for MgCl2), and soymilk pH (0.59 for CaCl2 and 0.56 for MgCl2). The optimal concentration of coagulant decreased with increasing soymilk heating time, but increased with increasing soymilk heating rate. The optimal concentration of coagulant for the soymilk produced by diluting the cooked soymilk is smaller than the soymilk with the same solid content but produced by cooking the diluted raw soymilk. It can be concluded that not only compositions of soymilk, but also the processing conditions of soymilk have an effect on the optimal concentration of coagulant.
Session 45G, Fruit & Vegetable Products: Vegetables (Fresh)
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