Extraction of isoflavones from soybean hypocotyl using aqueous ethanol

Abstract

Isoflavones were extracted from soybean hypocotyl using aqueous alcohols with different water contents. Malonylglycosides accounted for more than 70% of total isoflavones, followed by glycosides. Soybean hypocotyl contained 67 times more isoflavones than corresponding soybean cotyledon, making soybean hypocotyl ideal source for isoflavone production. Most suitable solvent for extracting isoflavones from soybean hypocotyls was 40-60% aqueous ethanol. Initial extraction rate of isoflavones from powdered hypocotyl was faster than with whole hypocotyl, although after 60 min, isoflavone concentrations in supernatant were equal regardless of particle sizes. Optimum temperature and time for extraction was 60degreesC and 1 hr, respectively. Malonylglycosides of isoflavones were hydrolyzed into their respective glycosides at 80degreesC. Volume of extraction solvent-to-hypocotyl ratio (v/w) must be above 6 for maximum extraction yield.