Teores de isoflavonas e capacidade antioxidante da soja e produtos derivados

Abstract

The objective of this study was to determine the antioxidant activity and isoflavone content and type of soy seeds and soy products. The antioxidant activity was measured using β-carotene bleaching and 2.2-diphenyl-1-picryl- hydrazyl (DPPH•) free radical methods. The total isoflavone content of soy products varied from 95 to 711 mg/100 g DW (expressed as aglycones) and total phenolics content from 101 to 413 mg equivalents of catechin/100 g DW. Soybeans presented 110 and 200 mg/100 g DW of isoflavones and total phenolics, respectively. The β-glycosides and malonylglycosides were the main forms of the isoflavones found in the whole flour, defatted flour and commercial defatted flour, similar to the soy seeds. The soy germ (hypocotyl) and the defatted soy flours presented the highest antioxidant activities in both methods (5.0 μmoles equivalents of trolox/g DW and ∼ 0.8 μmoles equivalents of BHT/g DW). Taking this into account, the results showed that total isoflavone and phenolic contents and isoflavone profile of soy products depend on processing conditions and that antioxidant activity varied significantly among products.