Soybeans with large seed size, uniformity, clear hilum, and high 11S/7S ratio are favored for soymilk and tofu making. In order to find ideal soybean lines for food making, sixty-eight soybean lines, which were selected from thousands of accessions in the USDA-Soybean Germplasm Collection, were planted in three successive seasons. Eight lines were identified from twenty-two lines harvested in 2014 (Stoneville, MS) to be suitable for tofu making as judged by chemical composition and sensory quality of tofu. The results provided important food quality information to the growers, breeders and tofu industries for their selection of soybean to improve food quality. In the filled tofu making and texture analysis study, the correlation between A3 subunit percentage and tofu firmness was significant (N=22. r = 0.77, P < 0.001). The result proved that the percentage of A3 subunits could be an indicator for predicting the firmness of tofu.

Producing desirable firmness is important in manufacturing tofu from soybeans. This study’s objective was to explore the environmental impact (location and year) on soybean chemical components and identify the correlations between chemical composition and the firmness of tofu made from soybeans planted in three locations over two years. Seventeen soybean Plant Introductions (PI) from the USDA Soybean Germplasm Collection and eight check varieties were planted in Mississippi, Virginia and Missouri in 2017 and 2018. Protein subunit composition, protein secondary structure, phytic acid content, Ca2+ and Mg2+ content were determined. The result showed that A3 subunit content was strongly correlated with tofu firmness. Environmental factors had a significant influence on some chemical components in soybean seeds as well as tofu texture. The current study confirmed the validity of using A3 peptide as a criterion for estimating tofu firmness in both tofu manufacturing and food-grade soybean trade.