FIELD: biotechnology, medicine. SUBSTANCE: invention relates to a method of preparing soybean protein serum and protein serum enriched with aglycone isoflavone. In soybean serum containing glycone isoflavones reaction of glycone isoflavone with an enzyme beta-glucoxidase and esterase or with an acid is carried out. Reaction with enzymes is carried out at 40-60 C, pH 4-8, for 2-48 h and reaction with an acid is carried out at pH 1-2, 80-90 C for 30-180 min and protein is extracted. Amount of aglycone isovlafones is 50% as minimum of isoflavones containing in serum. Method ensures to convert the most of glycone isoflavones to aglycone isoflavones which are used in therapy of cancer diseases. EFFECT: improved method of extraction, conversion and preparing the end product. 30 cl, 6 tbl
