Free Isoflavone (Daidzein and Genistein) Content in Soybeans, Soybean Meal and Dried Soy Hypocotyl Sprout using High Performance Liquid Chromatography (HPLC)

Background: Phytoestrogens are natural plant glucosides found primarily in legumes and grains. Phytoestrogens can interact with oestrogen receptors in the body either by mimicking or blocking the effects of oestrogen. Isoflavones are a major subclass of phytoestrogens and often comprise a substantial part of livestock feeds. This study was focused on the detection and quantification of free isoflavones especially genistein and daidzein in soy-based ingredients (soybeans, soybean meal and dried soy hypocotyl sprout) which are incorporated in the animal feed formulations.

Methods and Results: The simultaneous determination of daidzein and genistein in soybeans, soybean meal and dried soy hypocotyl sprout was carried out using the analytical technique high performance liquid chromatography (HPLC). The limits of detection and quantitation were 4.81 and 14.59 µg/100 g for daidzein and 3.06 and 9.58 µg/100 g for genistein respectively. The precision of the procedure was 2.73 per cent for daidzein and 2.88 per cent for genistein. The average daidzein and genistein concentration levels were (239.16 ± 0.21 and 238.68 ± 0.27 µg/100g) for soybeans, (397.24 ± 0.64 µg/100g and 443.85 ± 0.62) for soybean meal, (551.03 ± 0.54 and 742.59 ± 0.76 µg/100g) for dried soy hypocotyl sprout. The mean recovery percentages for daidzein and genistein were 92.8 per cent and 93.66 per cent respectively. The findings indicated that all the soy-derived components examined contained isoflavones and dried soy hypocotyl sprouts possessed higher concentrations of both daidzein and genistein.