The Study Of Optimization Of The Extraction Technolygy And The Antioxidant Activity Of Polysaccharides From Papaya

The ultrasonic-assisted hot water technology was used to the extraction of papaya polysaccharides, and the experimental index was measured by papaya polysaccharide yield. On the basis of single factor experiments, the quadratic regression orthogonal rotational combination design was adopted to optimize extraction process conditions of papaya polysaccharides, which obtained the optimum technological parameters.TiO2 photocatalyst doped with FeSO4 was synthesized by sol-gel method from tetrabutyl titanate. Then the TiO2 photocatalysts load on activated carbon are fills in non-thermal plasma - photocatalytic - adsorption integrated device which was used to decoloration of papaya polysaccharides. The effect of decoloration was assessed in terms of the rate of decolorization and of retention for papaya polysaccharides. The regression model of non-thermal plasma - photocatalytic adsorption decolourization process of papaya polysaccharides was established by mathematical method, which determined the best decoloring process conditions. During and after decolorizing, separation, purification, the antioxidant ability and reducing capacity of papaya polysaccharides in vitro were determined by some methods.The optimum extraction conditions were determined by use of the combination design method. The regression equation is as follows. Y=-39.955+0.0667z1+0.667z2+0.2425z3+0.837z4-0.002z3Z4-0.0013z12-0.0098z22-0.0008z32-0.005z22The experimental results show that the optimum extraction conditions were:time of ultrasonic processing 26.0 min, liquid-solid ratio 34:1, time of water-extraction 63.0 min and temperature of water-extraction71.0℃. Under these conditions, the papaya polysaccharide yield and its predictive value was 9.6% and 9.7%, respectively.Based on the discussion of the different weight coefficients’s affect on the experiment target, the decolorization rate and retention rate of polysaccharides accounts for 50% respectively. The optimum decolorization conditions were determined by the combination design method, which was based on the single factor experiments. The regression equation was obtained as follows.Y=51.72-0.625z1+0.80z2+0.73823+0.505z4+0.085z1Z4+0.059z2Z3-0.391z12-0.049z22-0.043 232-0.013z42The results showed that the decoloring rate and polysaccharide retention rate were 73.2% and 76.6% under the optimum conditions of decoloring time 23.0 min, voltage 24.0kV,activated carbon filling rate 41.0% and papaya polysaccharide concentration of 3.7 mg-mL"1, and the composite indicator reached 74.9%, which was the best result. Papaya polysaccharide extract decoloring rate and retention rate of comprehensive index reached 74.9, differ with predictive value of 73.7 by 1.6%.Using the liquid of crude extract, decoloring, separation and purification of papaya polysaccharide as the research objects, in vitro, study its ability of removing hydroxyl radical · OH, clearance rate of super oxygen free radical · O2- and total reducing power.The experimental results show that, the rate of removing hydroxyl radicals,super oxygen free radical · O2- and total reducing power of papaya polysaccharides after purification was 5.0%,8.2%, and 0.294, fell by 92.6%,85.3% and 92.6% respectively, compared with the coarse extraction liquid of papaya polysaccharides. Moreover, the antioxidant ability of papaya polysaccharide and purity were positively correlated. Further explained that not only papaya polysaccharide in papaya system has antioxidant activity, but also other components have certain antioxidant activity. In addition, decoloring process destroyed the part antioxidant of papaya polysaccharides.