Abstract
The difference in quality characteristics among main soybean varieties for tofu processing cultivated in Hokkaido was analyzed by 3-way (varieties, locations, and years) ANOVA. Although a significant difference was observed among the factors in the content of main components and 100-kernel weight, the effect of variety was smaller than that of either location or year. However, the effect of variety was the largest for breaking stress (firmness) of tofu. Characteristics that showed the highest correlation with firmness of tofu were 100-kernel weight and the rate of weight increase during soaking. All characteristics except breaking stress were analyzed by principal component analysis (PCA), and principal components (PC) were analyzed by principal component regression (PCR). The first PC (1PC) was significantly correlated with temperature during medium-late period of seed filling, and the second PC (2PC) with the number of seed filling days. In 2003, a cold summer year, the difference in temperatures during seed filling among locations seriously affected 1PC, and in 2004, a hot summer year, 2PC was decreased due to the reduction of the number of seed filling days. The regression by PCR indicated that breaking stress can be significantly explained by these PC. These results suggest that climate conditions that ensure the reasonable temperature and number of days for seed filling are important for tofu processing, in addition to the selection of soybean variety.
