Isoflavone Composition, Total Phenolic Content and Antioxidant Capacity of Soybeans with Colored Seed Coat

The influence of soybean seed coat color and genotype on antioxidant capacity, phenolic content and isoflavone profile was investigated. Isoflavone content and composition of 21 seed samples - yellow, green, brown, black and rarely mentioned ocher and reddish, were determined by high-performance liquid chromatographic analysis. Antioxidant capacity and total phenolic content (TPC) were evaluated spectrophotometrically. Significant correlation between total isoflavone content and total genisteins was established in all colored groups. Total isoflavone content was in the range from 2.11 mg/g in a green wrinkled sample to 5.24 mg/g in yellow seed. It was found that black genotypes had the highest TPC and antioxidant capacity, which were significantly different (p lt 0.05) from other colored soybeans. The obtained interconnections among analyzed isoflavones can be used as a model for estimation of their specific content.