Study On Extraction And Seperation Technology Of Soybean Isoflavone

Soybean isoflavone, a kind of active component extracted from soybean, has many important physiological functions. Extraction, isolation and purification of soybean isoflavone was studied in this paper.Taking genistein as standard sample, the optical density (OD) of the mixture standard solution of genistein and daidzein was examined at wavelength 259nm and 250nm. Through regression analysis of the relation between A(A259/A250) and C测定值/C实际值, two-wavelength UV spectrophotometry of soybean isoflavone was established.Single factor and orthogonal tests were designed to search optimum parameter of extraction technology of soybean isoflavone. The results demonstrated the yield of soybean isoflavone with ordinary extraction was 2.60% when soybean powder was soaked in 80% ethanol for one time, with 1:20 of the ratio of raw material to solvent and extracted for 3h at 60℃. The yield of soybean isoflavone with microwave-assisted extraction was 2.74% when soybean powder was soaked in 60% ethanol for one time, with 1:10 of the ratio of raw material to solvent and extracted for 90s under power 240W. Active component attained by the two extracting methods had not obvious distinction. However, the efficiency of microwave-assisted extraction was higher than that of ordinary extraction.Three purification methods of soybean isoflavone were compared. The result indicated the content of soybean isoflavone extracted by equal volume ethyl acetate and butanol was enhanced from 5.72% to 11.4% and 12.8%, respectively. The content of soybean isoflavone was enhanced from 5.72% to 37.6% by the macroporous resin DM201, eluted by 80% ethanal at the flow of 1.0 BV/h.Three different methods of isolation and purification of soybean isoflavone, including silica gel, polyamide column chromatograph and high speed countercurrent chromatograph(HSCCC) were compared in this study. The result showed the main ingredient of soybean isoflavone was basically separated, eluted by ethyl acetate- petroleum ether (10:3 v/v) at the flow of 1.0BV/h.Two elution peaks were attained by polyamide column chromatography and identified as soybean isoflavone glucosides. By high speed countercurrent chromatograph(HSCCC), daidzein and genistein could be effectively isolated. Chromatograph conditions were as follows: methyl alcohol: water: ethyl acetate: hexane(2:3:2:1) as the mobile phase, 1.5ml/min of the flow and 800rpm of the rotation .