Study Of Separating And Extracting Isoflavones And Soysaponins From Soy Molasses

The separation and enrichment methods of soy isoflavones and soy saponins which werebased on selective extraction of organic solvents from the phytochemical-rich soy molasseswere investigated, with the aim of providing basis for mass processing technology of soymolasses.Firstly, soy molasses was separated to two parts including supernatant and precipitationin steps of dilution, acidic preciptitation and centrifugation. The pretreatment conditions ofsoy molasses were determined by considering the effect of centrifugal speed﹑centrifugaltime and washing times to the components of the molasses precipitation, and the componentsof soybean molasses were analysed before and after the pretreatment process. The crudeextract was obtained by reflux extraction of the precipitation using acetone-aqueous solutions,which harvested by adjusting the solution acidity. According to the principles of extractingisoflavones and retaining saponins, the acetone-water ratio4:1, pH2.6, water temperature20oC were chosen to be the optimum technical parameter. Under the above conditions, theultrasound-assisted extraction of soybean isoflavone was investigated by single-factorexperiment, and the optimum technical parameter were ultrasonic frequency20Hz, ultrasonicpower1000w, ultrasonic time30min and the ratio solid to liquid1:20according to thecoefficient of recovery, content and yield of soybean isoflavone. Finally, the coefficient ofrecovery of final crude soy isoflavones was82.52%, with11.89%content and28.6%yield ondry basis. Every single factor correlation analysis was taken.The conditions of extracting soybean saponins from the ruflux extraction residue wasdetermined by single factor experiments through measuring the recovery ratio, content andyield on dry basis of the products. The optimum conditions were actone-water ratio4:1,solid-liquid ratio1:17, pH7.5, temperature56oC, and the soybean saponin recovery ratio inthe crude soybean saponins was92.10%, with content58.20%and the yield19.90%.Chloroform-methanol method was used to remove lipid from crude isoflavone product,which with the content of soybean isofalvone38.96%and yield ratio8.68%. The separationand purification of soybean isoflavones obtained from soy molasses were carried out with6different kinds of polar macroporous adsorption resin. The optimum resin was selected bycomparing the adsorption capacity of soybean isoflavone. The dynamic saturation adsorptionwas calculated from the static and dynamic adsorption curves of the selected macroporousresin. The flow speed of fluids, soybean isoflavone concentrations, and pH value of adsorbedliquid were selected as the parameters of single-factor experiment. Studies showed that theoptimum resin was D101with the static adsorption rate was96.44%and static desorption ratewas91.96%. Dynamic adsorption conditions were as follows: adsorption flow rate1.6mL/min, initial soybean isoflavone concentration0.423mg/mL, adsorption liquid pH5.0,adsorption rate97.18%, sample volume on10BV. Dynamic desorption conditions: desorptionliquid was80%ethanol, desorption liquid pH6.0, flow rate0.9mL/min, volume on4BV. Thepurity of Soybean isoflavones in the product reached to87.27%with yield ratio3.58%.Four precipitate methods were comparaed to gain soy saponins. Results showed that the purity of soybean saponin was highest with low temperature centrifugation while the recoveryand yield rates were lower. Under this condition, the purity of soybean saponins was80.12%with the recovery ratio86.34%and yield ratio on dry basis12.48%. The various componentsof soybean saponins composition and content were investigated through LC-MS analysis ofthe final product. The results showed that the soybean saponins B has a higher recovery ratethan other groups of soyasponins in the final product, illustrating that the extaction method isselective for the group B soyasponins.