High performance liquid chromatographic analysis of isoflavones in soybean foods

摘要

Phytoestrogen has been used as a suppliment of estrogen in order to treat osteoporosis. The representative phytoestrogens, isoflavones, are daidzein, genistein and formononetin which were present highly in our traditional soybean foods. The quantitative analysis of the isoflavone was done with a high performance liquid chromatography(HPLC) using a UV/VIS detector for the contents of the isoflavones in Astragali Radix, soybean sprouts, bean-curd(Tofu), soybean, soybean oil, pea, kidney pea, black bean(Yak-kong), soybean sauce(Ganjang), soybean paste(Doenjang), and fermented soybean(Maejoo). The content of free daidzein in soybean sprouts was 43.49+-3.41 mg/kg which was much higher than that in soybean, 14.52+-0.58 mg/kg, although total daidzein of fermented soybean was lower than that in soybean (Table 2, P<0.01). The amounts of free genistein in soybean sprouts, fermented soybean, and soybean paste were 27.63+-1.66 mg/kg, 291.52+-6.81 mg/kg, and 18.75+-1.33 mg/kg, respectively. The level of free formononetin in soybean paste was the highest among the soybean products (P<0.01). The content of formononetin in Astragali Radix, 9629.79+-0.57 #mu#g/kg, was about 160 times higher than that in soybean. Thus Korean traditional soybean products, black bean(Yak-kong) and Astragali Radix can be a good choice of phytoestrogens.