Mutant promising lines of black-seeded soybean for soy sauce preparation

Abstract Mutation through radiation can be used in soybean breeding to generate the plant genetic variability. Some mutant promising lines of black-seeded soybean have been selected, namely PA-3-PSJ, A-5-PSJ, A-7-PSJ, and B-4-PAIR and it is essential to study their quality for soy sauce preparation. Detam 1 and Mutiara 3 were used as variety checks. The results showed that all soybean lines belonged to large-seeded with the largest seed obtained in A-7-PSJ line (17.41g/100-grain), while Detam 1 and Mutiara 3 had smaller seed sizes than those of four lines. Conversely, both varieties had the highest protein contents (38.56-39.36% dw), followed by A-7-PSJ (37.79% dw), whereas the rest had lower contents. A considerable increase in protein content was observed in the koji, which about 88% to 93% existed as soluble protein. The protein contents of soy sauce were slightly different, ranging from 2.35% to 2.57% (dw). Detam 1 showed the highest score for color, aroma, taste and viscosity of soy sauce preferences, followed by B-4-PAIR and Mutiara 3 that had the same score and A-7-PSJ, which also gave the highest protein content and had the largest seed size. This suggests that B-4-PAIR and A-7-PSJ lines are promising for ingredients of soy sauce.