Objective:To study the physicochemical properties,structural characteristics,hygroscopic-ity,moisture retention and in vitro antioxidant activity of polysaccharides obtained from different ex-traction methods of dry and fresh Portulaca oleracea. Methods:Dry P. polysaccharide (DCPOP) was extracted by hot water method and fresh P. polysaccharide (FCPOP) was extracted by juicing method. The moisture,ash,pH,viscosity and other physicochemical properties of the extracted polysaccha-rides were studied. The structural characteristics of the two polysaccharides were compared by three-strand helical structure analysis,ultraviolet spectrum scanning,I2-KI reaction,differential scanning calorimetry (DSC),thermogravimetric (TG) analysis,and scanning electron microscopy. Hygroscop-icity,moisture retention and in vitro antioxidant activity were compared. Results:The moisture content of DCPOP was 7.82％,the ash content was 6.87％,the pH was 6.08,and the viscosity was 4.92 mPa‧s. DCPOP had not a three-strand helical structure,and basically did not contain nucleic acids and pro-teins. DCPOP had lower branches and shorter side chains,and might have starch or starch branch chains. The thermal decomposition temperature of DCPOP was about 260℃,and it had moisture ab-sorption and good moisture retention,as well as certain antioxidant activity. The moisture content of FCPOP was 8.11％,the ash content was 8.64％,the pH was 6.69,and the viscosity was 3.12 mPa‧s. FCPOP had a three-strand helical structure and basically does not contain nucleic acids and proteins. It had longer side chains and more branches,and there was no starch present. The thermal decomposition temperature of FCPOP was about 255℃,and it had moisture absorption and good moisture,as well as good antioxidant activity. Conclusion:The comprehensive performance of fresh P. oleracea polysac-charides obtained by direct juicing and alcohol precipitation was better than that of dry P. oleracea poly-saccharides,which had a good application prospect in the fields of skin care products and health care products.
Portulaca oleraceaPolysaccharidePhysical and chemical propertiesMoisture absorption and moisturizingAntioxidant activity
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