Separation And Purification Of Oligosaccharides From Soy Molasses

This paper was studied on using ultrafiltration technology, macroporous resins and ion exchange resins to extract soybean oligosaccharides from soy molasses.Firstly, the components and characteristics of soy molasses both before and after pretreating were determined. The transmittance of the supernatant was 88.1%, this supernatant was exactly clean and clear, the total sugar accounted for 60.48%. During the ultrafiltration process, the effect of pH value, temperature on membrane flux, the total sugar permeation rate and the cut-off rate of macromolecule proteins were studied through the single factor experiments. The optimum conditions were: 10000 molecular weight cut-off membrane, using diafiltration operating mode, pH7.0, 20℃. Under these conditions, almost all of the macromolecule proteins were removed, and about 75.65% of the oligosaccharide was retained, the transmittance of the UF permeate was 93.5%.Secondly, the decoloration effect of three types of macroporous resins on UF permeate was studied. AB-8 resin was chosen as decolorizing resin by comparing the decoloration. The suitable operation conditions were: room temperature, pH4.0, work solution speed of 1.5BV/h, the handling capacity was 4BV. Under this condition, the decoloration rate was over 90%, the total sugar loss was about 10%. The 70% aqueous alcohol was used as desorption reagent, the desorption rate reached 89.69%.At last, the main impurities existed in the crude soybean oligosaccharides were analysised and the purification effect both by nanofiltration and ion exchange resins on it were compared. the ion exchange technology was chosen ultimately. 001×7 was chosen as the cation resin, and D301 was chosen as anion resin. The operation condition was: room temperature, work solution speed of 1.2BV/h. The conductivity of the purified soybean oligosaccharides was very close to the tap water, nearly all of the nitrogenous material and most of the phenolic material was removed.After separation and purification, a pale yellow, translucent and clear soybean oligosaccharides syrup was prepared. The basic components of the end-product were: 66.73% solid, among this sucrose, raffinose, stachyose accounted for 53.43%, 6.90%, 14.92% respectively, ash 1.02%, no nitrogenous material was detected.