FIELD: biotechnology, biochemistry. SUBSTANCE: invention describes three methods of preparing protein concentrate that involve washing out with plant protein matter aqueous solution containing glucone isoflavones and carrying out reaction of glucone isoflavones with enzyme taken in the sufficient amount. Aqueous solution has pH value about isoelectric point of plant protein matter. Enzyme is at least a single enzyme beta-glucosidase and enzyme esterase. Reaction is carried out for time, at temperature and pH value that provide effective conversion of the most part of glucone isoflavones to aglucone isoflavones. Invention describes also method of extraction of at least 50% of isoflavone from plant protein matter in protein concentrate and involves washing out protein with isoflavone-containing plant protein matter aqueous solution at pH near isoelectric point of plant protein matter. Method involves carrying out interaction of glucone isoflavones with sufficient amount of enzyme for time, at temperature and pH value that provide effective conversion at least glucone isoflavones in concentrate to aglucone isoflavones and protein concentrate also. EFFECT: improved method of preparing. 31 cl, 1 tbl
