Concentration of phytoestrogens in soybeans and soybean products in Korea

Concentrations of total isoflavones in soybean varieties of different origins and soybean products were determined by high performance liquid chromatography. Wild soybeans showed the trend to have more isoflavone content than cultivars or landraces, showing mean value of 1528, 1265 and 1249 mg kg−1, respectively. There were no meaningful differences in the ratio of genistein and daidzein among the modern variety groups. Korean varieties including South Korea and North Korea seemed to have total isoflavone content more than Chinese varieties, although samples of Chinese varieties were limited. In a dried basis of soyfoods, total isoflavone contents were in order of soybean sprout, chungkukjang, soymilk, soybean curd, denjang, kochujang, respectively. Five soybean foods contributed 96% of total genistein and daidzein intake in Korea: soybean sprout, soybean curd, denjang, chungkukjang and soybean seed itself. According to a Korean National Survey Report and our data, the average Korean daily intake of isoflavone from soybean foods can be estimated as 21 mg day−1. © 2000 Society of Chemical Industry