Chemical composition and lipoxygenase activity of soybean (Glycine max L. Merrill.) genotypes, specific for human consumption, with different tegument colours

Abstract Recently, in Brazil, coloured-tegument soybean cultivars have been developed, such as those with brown and black teguments. Soybeans with black teguments have been widely used for decades due to their health benefits and their use in oriental folk medicine as a result of the presence of phytochemicals. They have been recognized as health-promoting functional food ingredients due to their antioxidant activity, and are also known to have anti-cancer, hypoglycaemic and anti-inflammatory effects and have been used in the treatment of various circulatory disorders. This study aimed to determine the proximate composition, fatty acid levels and lipoxygenase activity of soybean lineages with different tegument colours intended for human consumption. The lineage MGBR10-16601 which has a yellow tegument, presented the highest protein and lowest fat contents, with values of 37.6 g 100 g-1 and 18.3 g 100 g-1, respectively. The lineage MGBR10-16201, which also has a yellow tegument, was identified as free of lipoxygenase isoenzymes. The unsaturated fatty acid levels ranged from 18.48 to 31.37 mg g-1 and from 47.36 to 58.31 mg g-1 for oleic and linoleic acids, respectively. The lineage BRN07-50543, which has a black tegument, presented high total isoflavone levels (546 mg 100 g-1), with an oleic acid level above and linoleic acid level below the standards established by the Codex Alimentarius for soybean oil, with values of 31.37 mg g-1 and 47.36 mg g-1, respectively. The cultivar BRSMG 790A, which has a yellow tegument, presented the lowest isoflavone level (171.4 mg 100 g-1). All the genetic materials examined presented crude protein, fat, dietary fibre and ash levels within the commercial parameters established for soybeans.