关键词: 南瓜多糖, 生物转化, 理化性质, 抗氧化活性

Abstract: Pumpkin polysaccharide is an important active ingredient, Since our previous study has indicated that Lactobacillus plantarum biotransformation enhanced scavenging ability of 1, 1-diphenyl-2-trinitrophenylhydrazine free radicals of pumpkin polysaccharide, in this study, the chemical composition, monosaccharide composition, structural properties, rheological properties and antioxidant activities of pumpkin polysaccharide（PP）and biotransformed pumpkin（BPP）were tested to further explore the changes of physicochemical properties and antioxidant activities of PP. The results showed that the content of glucuronic acid and galacturonic acid in BPP were increased, while the content of glucose were decreased. Macromolecular structures were decomposed but the structure of functional groups were not changed. The viscosity of BPP was higher than that of PP at the same shear rate and concentration. BPP and PP were dose-dependent on the scavenging ability of 1, 1-diphenyl-2- trinitrophenylhydrazine, hydroxyl radical, superoxide anion radical and iron ion. The antioxidant effect of BPP was better than that of PP in vitro. Meanwhile, compared with PP, BPP could significantly improve the survival rate and glutathione oxidase activity of UV-damaged yeast cells（P<0.05）. In summary, the antioxidant activity of BPP was improved, which may be related to the change of physicochemical properties. The results of this study will provide theoretical basis for the further development and utilization of pumpkin polysaccharide and preparation of related functional food.

Key words: pumpkin polysaccharides, biotransformation, physicochemical properties, antioxidant activity