ISOFLAVONE CONTENT IN COMMERCIAL SOYBEAN FOODS

The concentration and distribution of isoflavones in 29 commercial soybean foods, categorized into soy ingredients, traditional and second-generation, were evaluated by high-performance liquid chromatography and photodiode array detection. Twelve isomers were quantified, three aglycons (daidzein, genistein, glycitein) and nine glucosides (daidzin, genistin, glycitin; 6''-O-acetyldaidzin, -genistin, -glycitin; 6''-O-malonyldaidzin, -genistin, -glycitin). Compared with unprocessed soybeans, high-protein say ingredients contained similar concentrations, except alcohol-leached say concentrate. Traditional soybean foods showed differences between nonfermented and fermented foods. Nonfermented foods had greater levels of glucosides, while in contrast, greater levels of aglycons were found in fermented foods. Second-generation soy foods contained only 6-20% of the isoflavones of whole soybeans. The variety of soybean, method of processing, and addition of other components affect the retention and distribution of isoflavone isomers in soy foods.