extraction of genistein from korean soybean by sub- and supercritical water

초록

Isoflavones are phytochemicals found in a variety of plants including soybeans. They may contribute to many of the health benefits attributed to soy foods. Isoflavones, such as glycosides daidzin, glycitin, and genistin, are quite abundant in soybeans. Aglycones such as daidzein and genistein, derived from these glycosides, are frequently examined in their chemical structures. These isoflavones have several biological effects and are considered to be anti-carcinogenic, beneficial to human health. The genistein of these has friendly chemical structure estrogen, in particular. As a result, it have associated a diet with a lowered risk for certain diseases, such as breast and prostate cancers, osteoporosis and cardiovascular diseases, and have shown anti-cancer. Ambient liquid water at standard state has strong dipole moment and high dielectric constant, highly effective hydrogen bond. These feature results in lower solubility for non-polar organic and gases and high solubility for dissociating ionic salts. The sub- and supercritical water at near critical point shows reduced lower density and dielectric constant. Under these sub- and supercritical conditions, water behaves more like non-polar solvent. The aim of this work was to set up the methodology to extract genistein from natural Korean soybean using sub- and supercritical water. The experimental conditions were changed with densities and dielectric constants according to the same values of methanol, ethanol, and hexane to compare the yields of genistein with the temperatures and pressures. The critical points of water are 647 K and 221 bar. From the experimental condition of water at 573 K and 250 bar continuously injected into the extraction vessel, the amount of extracted genistein was gradually decreased with the effluent times. The extracted amount of genistein was the two times larger than that using the solvent extraction of water/ethanol, 40/60 (vol.%).