The Study On The Purification Process Of Soybean Isoflavones

Soybean isoflavones is a sort of bioactive substance extracted from soybean, which has many important physiological functions. The extraction and purification process of soybean isoflavones were studied in this research which was proven to provide a direction for isoflavones industrialization. The packed extraction tower was used to extract soybean isoflavones. The effect of the operation conditions such as current velocity and volume ratio of two phases on the yield of soybean isoflavones was investigated. Through orthogonal experiment, the optimal extraction conditions were obtained as following: the volume ratio of two phases is 4:1, the dilute times of soybean slurry is 3 times, the current velocity of soybean slurry is 1ml/min.The yield of 95% was obtained under the optimal operations with great disposition capability and the continuous operation can be carried out easily to improve the efficiency obviously. The result shows that, the continuous extraction process with packed extraction tower can be used in the extraction of soybean isoflavones, which has a promising industrial application.Based on the solubility diversity of different isoflavone monomer in the same solvent, the purification methods of Daidzin and Glycitin were obtained with extraction and crystallization. The technics flow for the preparation of Daidzin and Glycitin is shown in the article. The Daidzin was obtained with a purity of 90% using acetone circumfluence extraction and the hybrid extraction of acetone and ethyl acetate. The Glycitin was obtained with a purity of 94% using ethanol crude extraction and methanol recrystallization. The preparation method is of simple operation and low cost, which can also realize industrialization easily. Nanofiltration was used for the study on soybean isoflavones. The effect of solute concentration and solvent concentration on retention rate and flux was investigated. The retention rate of daidzin in methanol solution using DK NF membrane is higher, which can reach 90%; The retention rate of daidzin in water solution is only 50%. The solute concentration and solvent concentration had no direct effect on the flux. The main effect on the flux is the character of solvent. The result shows that, NF membrane can be used for concentrating isoflavone, which provides a new method for the preparation of isoflavones.