Yield and Quality of Soymilk and Tofu Made from Soybean Genotypes Grown at Four Locations

Soyfoods are becoming popular among American consumers because of potential health benefits. However, specific information about the kind of soybean [Glycine max (L.) Men.] seed desirable for soyfoods preparation is limited. The objectives of this study were to compare soymilk and tofu prepared from 12 soybean genotypes grown at four locations in the southern USA during 1995 to identify genotypes suitable for soymilk and tofu manufacture and to determine effects of seed traits on yield and quality of soymilk and tofu. Location effects were significant only for soymilk solids and tofu strength. Soymilk yield with a mean value of 5.1 mL g⁻¹ seed was not affected by soybean genotype. Significant genotypic effects were observed on tofu yield, which varied from 0.82 to 0.91 g mL⁻¹ of soymilk. Tofu yield was significantly correlated to seed size (+0.31), seed oil (+0.74), rate of water absorption after 1 and 16 h of soaking (+0.38 and +0.56, respectively), and seed protein (−0.82). Seed protein content, seed size, and soymilk solids were significant determinants of tofu yield (R² = 0.80). Two variables, soymilk index (SI) and tofu index (TI), were calculated to compare overall suitability of soybean genotypes for soymilk and tofu production. SI was calculated by summing yield, total solids, protein content, and whiteness index of soymilk. TI was calculated by summing yield, protein, whiteness index, and strength of tofu. Seed oil content and size were significant determinants of SI (R² = 0.41), whereas soymilk color, seed size, and seed protein content were significant determinants of TI (R² = 0.52). The SI and TI values indicated BARC-9 to be a desirable genotypes for soymilk and for tofu preparation. This journal article No. 205 from Virginia State Univ., Agric. Res. Stn. is a contribution from Regional Research Project (RR7) to develop food uses of soybean by a multi-disciplinary team from 1890 Land Grant Institutions. This research was supported by USDA-CSREES funds allocated to the Association of Research Directors. The use of any trade names or vendors does not imply approval to the exclusion of other products or vendors that may also be suitable