Isoflavones, Anthocyanin and Fatty Acid Composition in Soybean Genotypes (Glycine max (L.) Merrill) at Growth Stages R6, R7 and R8.

Special soybean varieties for human consumption with large seed size and black seed coat are consumed as vegetables or “edamame”. For these products, soybean harvest is recommended at R6 growth stage, when seed filling is complete. Chemical compounds related with nutrition and health are important to soybean consumption. Therefore, oil, protein, fatty acids, isoflavones and anthocyanins were compared in seeds of the breeding lines BRM09-50995 (black seed coat), BRM11-51428 (yellow hilum and seed coat) and BRM08-50643 (yellow seed coat and black hilum) harvested at R6, R7 and R8. BRM09-50995 presented the largest seed size (weight of 100 seeds) at all growth stages (R6 41g, R7 48g and R8 30g). All lines presented higher oil and protein content at R8. In average, from R6 to R8, oil content ranged 22.8% - 24.6% and protein 36.6% - 41.3%. BRM11-51428 presented lower oil content (20.4%) at R6 and the highest protein content (44.3%) at R8. Palmitic, stearic and linolenic acids were higher at R6, while linoleic was higher at R7 and oleic at R8. In average of the three stages, BRM08-50643 showed the lowest content of oleic (18%), and the highest content of linoleic (55%) and linolenic acids (11%). At R8, BRM11-51428 showed the highest content of oleic acid, while BRM09-50995 had the highest content of linoleic and the smallest of linolenic. Isoflavones glucosides and aglucones were higher at R8, but the malonyl forms were higher at R7. BRM09-50995 presented the highest content of total isoflavone (471.85 mg/100g). Total aglucones increased about 3 times from R6 to R8. Anthocyanins were present only in BRM09-50995, with a significant larger amount (154.74mg/100g) at R7 than at R6 (27.4 mg/100g) and R8 (41mg/110g). Therefore, BRM09-50995 with black seed coat could be a good vegetable source to process a nutritive and functional soybean food.