Optimization Of The Extration Technolygy And The Antioxidant Activity Of Pumpkin Polysaccharides

The ultrasonic-assisted hot water technology was used to the extraction of pumpkin polysacchraides, which is measured by the polysacchraides yield. The non-thermal plasma reactors were designed, manufactured, and applied to the decoloration of the polysaccharides from pumpkin, according to the principle that dielectric barrier discharge (DBD) can generate non-thermal plasma (NTP). The non-thermal plasma-photocatalysis-adsorption reactors were used to decolor the polysaccharides from pumpkin when the acticarbon particles loaded the TiO2 were added into the NTP devices, because the free radical can be produced by photocatalysis in the stimulation of the ultraviolet which was generated through DBD. The antioxidant activities of the polysaccharides frompumpkin were investigated with Vc as the refrent. The antioxidant activities of the polysaccharides, which were treated withor without the non-thermal plasma-photocatalysi-absorption technology, were compared.The optimun extraction conditions were determined by use of the combination design method, which was based on the single factor experiment. The regression equation is as follows.Y=37.0+0.415X1+0.200X2+0.345X3+0.415X4-0.343X12-0.294X22-0.333X32-0.406X42 The results showed that the optimun extraction conditions were:time of water-extraction 11.5min, temperature of water-extraction 71.8℃, solvent ratio 52.5:1(ml:g), and time of ultrasonic treatment 16.3min. Under those conditons, the pumpkin polysaccharides yield reached 37.4%.Based on the discussion of the different weight coefficient’s affact on the experiment target, the rate of decolorization and the retention rate of polysaccharides accounts for 50% respectively. Decolorization of polysaccharides from pumpkin was studied by using non-thermal plaama-photocalatysis-adsorption reactor. The ptimun decolorization conditions were determined by use of the combination design method, which was based on the single factor experiment. The regression equation is as follows.Y=49.0+1.31Z1-0.0239Z12+3.85Z2-4.64Z22+0.533Z4-0.00536Z42+0.234Z2Z3-0.280Z3 The results showed that the optimun decolorization conditons were:processing time 27.4min, voltage of electrodes 12.0 Kv, rate of the solution 49.7ml/min and filling rate of acticarbon particles 15%. Under those conditons, the synthetical of decolorization and retention rate of polysaccharides reached 78.0%.The same batch of fresh pumpkin pulp tissue were used as experimental materials. The results of antioxidation test showed that the polysaccharides from pumpkin had some antioxidant activity. Comparing with the Vc, the ability of scavenging hydroxyl radical was equivalent to 7.32% of Vc. The ability of scavenging superoxide anion radical was equivalent to 8.06% of Vc. Reducing power was equivalent to 5.06% of Vc. The ability of chelating metal ion was weak, equivalent to 1.19% of Vc. The antioxidant activities of the polysaccharides treated by the non-thermal plasma-photocatalysis technology decreased by 13.2% to 35.6%.