Extraction And Purification Of Soybean Isolfavone From Say Sauce Residue

Soy sauce residue (SSR) is the main by products in the soy sauce process, duringwhich the main raw materials—vegetable proteins and starch such as soybean mealand wheat flour undergo the process of cooking, starter propagation, fermentation andextraction. Normally, SSR is sold as crude feed and fertilizer at low price orsometimes directly threw out, resulting in serious environmental pollution and lowefficiency of SSR utillization. SSR is a good naturally active compounds resource andextracting bioactive soybean isoflavones from SSR is of great significance to improvethe ultilization of the soy sauce residue. In this study, the soybean isoflavone wasextracted from SSR using ethanol. Then the ultrafiltration and resin separation andpurification technology were used for the further purification. The structure of thepurified isoflavones was identified using High Performance Liquid Chromatography(HPLC), IR and HPLC MS，and its biological activity was tested in vitro experiment.The main contents of this paper and the results were summarized as follows.1. The optimum extraction conditions of isoflavones from soybean residue werestudied by using single factor and orthogonal design test. The effects of alcoholconcentration, extraction temperature, extraction time and the ratio of soy beanresidue to extraction were investigated. The ratio of soy bean residue to extractioninfluenced the yield of soybean isoflavone most, while the time of say bean residue toextraction influenced least. The optimum extraction conditions were the alcoholconcentration70%, the temperature80°C, the extraction time3hours and the ratio ofsoybean residue to extraction1:35, the yield of soybean isoflavone could reach1.2%and the content of isoflavones in the extraction was up to4.3%;2. Ultrafiltration (UF) with molecular weight cutoff (MWCO) of20kDa, wasused to purify the extraction of isoflavones. The effects of UF parameters on themembrane flux were analyzed. The optimum extraction conditions weretransmembarne pressures0.9MPa, ultrafiltration temperatures40°C, feed velocity4.2L/min, feed concentration5g/L, pH2,1fold addition of solvent, the recovery rate of soybean isoflavone could reach71.54%. The resistance model was established basedon the data obtained during UF process and the formula of the ultrafiltrationmembrane flux was obtained. Comparing the clarity, color of the liquid and content ofthe soy isoflavones after and before UF process, the results showed that UF processhas a good effect on the clarification and decoloration of solution, the content ofisoflavones in the filtrate was up to6.27%, the content increased by45.8%. Duringmembrane cleaning,5%NaOH+benzene sulfonic acid sodium salt+10-5ppm sodiumhypochlorite showed better cleaning effect on the membrane and the membrane fluxcould be restored to about99.25%of the original.3. The optimum purification of soy isoflavones by AB8macroporous resin werestudied and the results showed that: the adsorption capacity of AB8macroporousresin reached to1.7665mg/g wet resin after static adsorption8h, which was up to90%saturated adsorption amount of AB8macroporous. When the operation conditionswere flow velocity2BV/h, feed concentration5mg/mL, feed volumes2BV, gradientelution35%60%95%aqueous ethanol solution, the recovery of soybean isoflavonecould reach71.54%and the the content of isoflavones was up to43.9%in the60%eluent.4. By measuring DPPH radical clearance rate and superoxide radical clearancerate, the influence of isoflavones purified by ultrafiltration and resin separationtechnology on the antioxidant activity was studied. The isoflavones prepared fromSSR had higher antioxidant activity than those from soy beans, and the isoflavoneswere composed by genistin and genistein, and prossibly by other five isoflavonemonomers.