The concentration and distribution of isoflavones in 29 commercial soyabean foods, categorized into soya ingredients, traditional and second-generation, were evaluated by HPLC and photodiode array detection. 12 isomers were quantified, 3 aglycons (daidzein, genistein, glycitein) and 9 glucosides (daidzin, genistin, glycitin; 6"-O-acetyldaidzin, -genistin, -glycitin; 6"-O-malonyldaidzin, -genistin, -glycitin). Compared with unprocessed soyabeans, high-protein soya ingredients contained similar concentrations, except alcohol-leached soya concentrate. Traditional soyabean foods showed differences between nonfermented and fermented foods. Non-fermented foods had greater values of glucosides, while in contrast, greater amounts of aglycons were found in fermented foods. Second-generation soya foods contained only 6 to 20% of the isoflavones of whole soyabeans. The variety of soyabean, method of processing, and addition of other components affect the retention and distribution of isoflavone isomers in soya foods.
Journal Citation
42(8):1666-1673, JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
