Extract Polysaccharides From Soybean Hull And Modified By Dry Process Grafting

In this work, the raw materials are from Soybean oil processing enterprises. The soybean hull hemicellulose polysaccharide have been conducted by alkaline and subcritical water extraction. Preliminary structure identification of the main components of the extracted polysaccharide was obtained, and the main component of polysaccharide extracted by subcritical water at 130 °C was isolated and purificated. The scavenging DPPH and hydroxyl radical capacity of the polysaccharide and its purification components were studied. The soybean polysaccharide extracted by subcritical water was modified with protein by the dry grafting, the purpose of investigation was to enhance the emulsification and emulsion stability of polysaccharide, and for the future of the theoretical basis for the development and utilization of soybean hulls polysaccharide. The results of the study are as follows:(1) Hemicellulosic fractions were extracted from soybean hull with various concentrations of NaOH at 50 °C for 5 h. The chemical compositions and physicochemical properties were determined by high performance anion exchange chromatography(HPAEC), Fourier transform infrared spectroscopy(FT-IR), thermogravimetric analyzer(TGA), and 13 C and 2D nuclear magnetic resonance(NMR) analysis. The crystallinity of soybean hulls treated and untreated by alkali liquid was examined by X-ray diffraction(XRD). The sugar analysis results indicated that all of the hemicellulosic preparations were heteropolysaccharides containing arabinose, galactose, glucose, xylose and mannose. According to the spectral analysis, hemicelluloses from soybean hull were assumed to be L-arabino-4-O-methyl-D-glucurono-D-xylan. Xylose was the predominant monosaccharide in the hemicellulose fraction 1(H1), and it accounted for 40.1%-48.8% of the total neutral sugars. It was found that hemicellulose fraction 3(H3) had the highest thermal stability and H1 had the lowest thermal stability. The crystallinity index(CrI) was found to be about 20.8%, 14.3%, 10.9% and 4.7% for soybean hulls, untreated and treated with 1.5, 2.0, and 2.5 M NaOH, respectively.(2) The polysaccharides of soy hulls were extracted by hot-compressed water at temperatures(from 110 °C to 180 °C) and various treatment times(10–150 min) in a batch system. It was determined that a moderate temperature(150 °C) and short time(60 min) are suitable for the preparation of polysaccharides. The structure of xylan and the inter- and intrachain hydrogen bonding of cellulose fibrils in the soy hulls were not significantly broken down. The polysaccharides obtained were primarily composed of α-L-arabinofuranosyl units, 4-Omethyl-glucuronic acid units and α-D-galactose units attached with substituted units. A sugar analysis indicated that arabinose was the major component, constituting 35.6–46.9% of the polysaccharide products extracted at 130 °C, 140 °C, and 150 °C. After the subcritical water treated, soybean hull cellulose crystallization index increased from 21.8% to 28.9%, the results show that the experimental temperature of subcritical water cannot destroy the hydrogen bonding structure of cellulose.(3) Polysaccharide, which was extracted at 130 °C for 1h from soybean hulls, was separated and purified. Deproteinated polysaccharide of soybean hull were purified using DEAE-52 cellulose chromatography to get three purified fractions of P-1, P-2 and P-3. The HPAEC analysis showed that P-1 components were mainly composed of mannose, and hardly containing xylose components. P-2 and P-3 components were mainly composed of galactose and arabinose xylan. And removing DPPH and hydroxyl free radical ability of cruded and purified polysaccharide were tested, the test results showed that the coarse polysaccharide has good oxidation resistance of soybean hulls, after separation and purification of antioxidant capacity of components with obvious decline. Soybean hull polysaccharide on free radical ion removal ability of coarse polysaccharide of soybean were hulls>P-3>P-1>P-2.(4) Soybean hull polysaccharide was modified by protein graft so as to improve the emulsification and emulsion stability, control the content of protein were 10%, 20%, 30%, 40%, 50% and 60%. With color chromatic meter, infrared spectra, thermogravimetric analysis and ultraviolet spectrophotometer, chemical and physical properties of the modified products were analysised. The experiment results showed that the higher protein content after reaction of the sample, the smaller the whiteness values of red and yellow value also increases. As can be seen from the thermogravimetric analysis, thermal stability of the modified material has the obvious improvement. Full wavelength scanning spectra measured in the ultraviolet spectrophotometer demonstrated the success of the grafting reaction and the reaction change of poly xylose. The result demonstrated that modified polysaccharide of emulsification and emulsion stability was obviously improved, emulsification with 40% emulsification is the best, and the stability of emulsification with 30% is the best, similar results can also be obtained in salt solution.