Extraction, Purification, Rheological Property And Antioxidant Activity Of Polysaccharides From Coix Lachryma-jobi L.var.ma-yuen

Coix seed is used as raw materials in this research. The extraction, purification, rheological property and antioxidant activity of polysaccharides from Coix Lachryma-jobi L.var.ma-yuen were studied. The main contents and results were as follows:1. The Enzymatic Hydrolysis and Ultra sonic Wave were used in Extraction of Coix Seed Polysaccharide. The results showed that The optimal extraction conditions: enzymatic hydrolysis pH 6.5, enzymatic hydrolysis temperature was 45℃, enzymatic hydrolysis time was 120min and the ultrasonic time was 25min.Under optimized conditions, the Coixan yield is 16.99%.2. Viscometer method was used to explore the viscosity of coixan under different conditions.The experimental results showed that the polysaccharide concentration, temperature, ultrasonic treatment time, pH, trichloroacetic acid, metallic Na+ ions, antioxidants VC, oxidants H2O2 and other factors might affect the viscosity of coixan.Therefore,during polysaccharide extraction, purification and other processing, the conditions should be strictly controlled.3. The effect of the Sevag method, trichloroacetic acid, enzymatic and enzymatic hydrolysis combined with Sevag method for removal of protein from coixan were compared.The results showed that, the papain method combined with Sevag method is better than the other three method. It is a suitable and effective method for removing of protein from coixan.4. The Decolorization of Polysaccharides from Coix Seed with Hydrogen Peroxide was studied.The effects of temperature, pH, amount of hydrogen peroxide and time on polysaccharide decolorization were explored. Using the orthogonal design, conditions were optimized as follows:temperature 60℃,pH 8,the dosage of hydrogen peroxide 4.0ml and bleaching time 3 hours.Under optimized conditions, the decolorization rate of coixan is up to 94.21%.5. After defatting, removing protein, decoloring, the coixan was dialyzed with flowing water for 2d, purified by DEAE-52 ion-exchange cellulose chromatography, and then chromatographed over Sephadex G-75 with a column of (0-3) mol/L NaCl to obtain pure coixan. The results showed that:there are no characteristic absorption of nucleic acid or protein in the polysaccharide in its UV-vis spectrum at 260nm and 280nm. IR spectrum showed that coixan have characteristic absorption peaks of polysaccharide, and it had a-pyran ring domain.6. The antioxidant activity of coixan was estimated through getting rid of superoxide radical (O2·),hydroxyl radical (·OH) and DPPH·. The experimental results showed that coixan had a stronger removal ability on superoxide radical (O2·), when it's concentration reached 5mg/mL, its clearance rate can reach 43.30%. The ability for coixan getting rid of radical was weaker than that of VC.