Tofu was prepared from 13 soybean varieties according to three different methods (bench, pilot, and production methods). Different soybean varieties showed significant differences in storage protein composition (glycinin and beta-conglycinin). The beta-conglycinin (7S) and glycinin (11S) contents were 7.3-9.9 and 14.1-22.9% on the dry matter basis, respectively. The 11S/7S protein ratio varied from 1.64 to 2.51 among the varieties. Glycinin content and 11S/7S protein ratio of the 13 varieties did not change significantly from soy milk to tofu for the production and pilot methods. Soybean 11S/7S protein ratio positively correlated with the 11S/7S ratio of soy milk and tofu (0.57 < or = r < or = 0.83, p < or = 0.01). The correlation coefficient depended on the processing method. Processing method affected 7S and 11S protein contents of tofu and their contribution to tofu hardness, yield, and sensory quality. This may explain in part the contradictory findings of the relationships between storage proteins and tofu quality because processing methods differed in various studies.

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The effects of soymilk solid content ("Brix) and coagulation time on the yield, proximate composition, and textural characteristics of dry tofu were investigated. Soymilk "Brix significantly QI < 0.05) influenced tofu yield, fracturability, hardness, springiness, cohesiveness, and chewiness. Among soymilk "Brix of 7. 1, 7.8, 8.4, and 9.2 tested, "Brix 9.2 (9:l water/bean ratio) produced the lowest yield (201g/I OOg bean), but the highest fracturability, hardness, cohesiveness, springiness, and chewiness. Coagulation time for 5 rnin resulted in a significantly lower tofu yield but higher cohesiveness than coagulation for I5 min. The fracturability and hardness of tofu from 9.2 "Brix soymilk coagulated for 5 rnin were greatest (18.0 and 19.6 kg, respectively).Lower soymilk "Brix and longer coagulation time produced tofu with a significantly higher moisture content. Dry tofu contained approximately 75-78 % moisture (wet basis), 5558% protein (dry basis), and 20-23% fat (dry basis).

Crude 11S and 7S proteins of three soybean cultivars were fractionated, and tofu was prepared from soymilk with 11S/ 7S protein ratios of 1.6 to 3.2. Higher 11S/7S ratio produced lower yield (pՅ0.05) of Vinton and Sturdy tofu. Higher 11S/7S ratio resulted in higher firmness of Proto and Sturdy tofu. Increase in 11S/7S ratio increased cohesiveness of Sturdy tofu. The maximum extent of decreasing Vinton tofu yield and increasing Proto and Sturdy tofu firmness was ~10% of the unmodified tofu. Results indicated that tofu characteristics were cultivar dependent and manipulation of 11S/7S ratio may not result in substantial effects on tofu yield or quality.