The potential of crude okara for isoflavone production

•Opportunities to utilize okara as a source of isoflavones are shown.•Environmental friendly solvents (ethanol and water) are used as extraction solvents.•The crude okara can be used for extraction without prior drying.•50% Ethanol is sufficient for a high yield of isoflavones.•The highest purity/lowest protein concentration was found at 80% ethanol.