Separation Of Soybean Saponins From Soybean Meal By A Technology Of Foam Fractionatin And Resin Adsorption

The recovery of a high-value material from an industrial wastewater or residue has attracted the attention of more and more people and it has been an important issue in many fields. Soybean meal is a residue generated during the process of producing soybean products. This is the first report on soybean meal is used to prepare high-value soybean saponins by a technology of foam fractionation and resin adsorption. The main results are as follows :First in leaching, ethanol was used to leach soybean saponins from soybean meal for increasing the leaching percentage of soybean saponins and removing the proteins. When the leaching conditions were the quality of soybean meal 100 g, 700 mL 75%ethanol, water bath temperature 75 oC, ultrasonic time 2 h and balkflow 2 times, the quality of soybean saponinsl 1.16 g was obtained.The foam fractionation was used to enrich soybean saponins from the leaching liquor for removing impurities. When the optimal conditions of the first stage were temperature 60 oC, volumetric air flow rate 200 m L/min, the total soybean saponins concentration of the feeding solution 2.0 g/L, loading liquid volume 300 m L and initial pH 4.0, the enrichment ratio and the purity of soybean saponins were 4.45 and 67%, respectively. Meanwhile, the residual solution obtained from the first stage was used as the feeding solution in the second stage. When the optimal conditions of the second stage were temperature 30 oC, loading liquid volume 279 m L, volumetric air flow rate 300 mL/min and initial pH 4.5, the total soybean saponins concentration of the foamate reached 2.17 g/L and it was almost equal to that of the initial feeding solution in the first stage. The total recovery percentage of soybean saponins reached to 74% by the two-stage foam fractionation.The macroporous resin adsorption was used to purify soybean saponins from the foamate in the first stage. The performance of static/dynamic adsorption and desorption were investigated in this study. Base on the single factor experiment of macroporous resin adsorption, 5 g of AB-8 macroporous resin could be determined. Response surface method was used for determining the optimum conditions of static adsorption which were temperature 30 oC, pH 2.00, rotation speed 200 r/min and adsorption time 180 min. Under these optimal conditions, the adsorption quality of AB-8 macroporous resin reached 19.31 mg/g. The dynamic adsorption and desorption were performed on a lab-scale glass column packed with AB-8 macroporous resin. When the optimal conditions of the dynamic adsorption were the column volume 20 m L and the feeding flow rate 1.25 BV/h, the breakthrough volume was 40 mL and the adsorption capacity was 17.8 mg/g. In the dynamic desorption of SS, the optimum volume of desorption solution was 3.0 BV and then the desorption percentage of SS reached 89%. So the purity of soybean saponins in the freeze-dried powder from the desorption solution was 88.4%.