| The Chinese yam (Dioscorea opposita Thunb.) tuber was studied as materials after harvest and then the rough polysaccharide was extracted immediately. First of all, yam tuber polysaccharide was deproteinized through many methods to find out the best way to take off the protein. Secondly,different varieties of Chinese yam tuber polysaccharides in vitro antioxidant capacities were determined aiming to find out the best Chinese yam variety.Then the antioxidant capacity comparation between the rough polysaccharide and refined polysaccharide were determined in vitro.Finally, refined polysaccharide was purified to find out the composition of polysaccharide preliminarily. The results showed as follows:1. The effect of trypsin-TCA method to take off the protein was the best way.The optimum conditions of removal of protein were:enzyme dosage was0.5ml, enzymolysis temperature was37℃, enzymolysis time was45min, enzymatic pH was7.5, and TCA concentration was6%.2. The in vitro antioxidant capacities such as reducing power, DPPH·radical clearance,·OH free radical clearance and O2-·free radical clearance were determined on different varieties of Chinese yam tuber polysaccharides. The comparative analysis showed that the strongest variety of in vitro antioxidant capacity was B1Chinese yam.3. The reducing power, DPPH·radical clearance,·OH free radical clearance and O2-·free radical clearance were determined respectively on B1Chinese yam. The results indicated that the reducing power of the rough polysaccharide was stronger than the refined polysaccharide,but the three free radical clearance ability of the rough polysaccharide were all weaker than the refined polysaccharide.4. The yam refined polysaccharides were purified by DEAE-SFF column and Sephadex G-75column.After elution by different concentration of NaCl solution, two neutral polysaccharides and four kinds of acidic polysaccharides were gained. |
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