干燥方式对白三叶多糖理化性质和抗氧化活性的影响

Effects of Drying Methods on Physicochemical Properties and Antioxidant Activity of Polysaccharides from the Aerial Part of Trifolium repens L.

本研究采用水提法提取白三叶多糖,比较3种干燥方式(热风干燥、冷冻干燥、真空干燥)对白三叶多糖理化性质和抗氧化活性的影响,旨在筛选出白三叶多糖的最佳干燥方式。结果表明:冷冻干燥多糖的得率显著高于热风干燥和真空干燥(P<0.05)。干燥方式对多糖总糖质量分数、硫酸基质量分数和糖醛酸质量分数有显著影响(P<0.05),总糖和糖醛酸质量分数由高到低的干燥产品顺序依次为:冷冻干燥>真空干燥>热风干燥。干燥方式对多糖蛋白质质量分数、氨基糖质量分数、水分质量分数、p H值和相对黏度无显著影响(P>0.05)。冷冻干燥多糖的溶解时间显著短于热风干燥多糖和真空干燥多糖(P<0.05)。白三叶多糖含有少量蛋白质或多肽,并且具有三股螺旋结构。冷冻干燥多糖的还原力、1,1-二苯基-2-三硝基苯肼自由基清除活力和2,2’-联氨-双-(3-乙基苯并噻唑啉-6-磺酸)二胺盐自由基清除活力均显著高于热风干燥和真空干燥多糖(P<0.05)。因此,冷冻干燥是保持白三叶多糖抗氧化活性的较好方法。

This paper reports the results of a comparative study of the effects of three different drying methods(hot air drying,freeze drying and vacuum drying)on the physicochemical properties and antioxidant activity of water-soluble polysaccharides(WSP)from the aerial part of Trifolium repens L.The aim of the study was to find out the best drying method for WSP.The results showed that the yield of freeze-dried polysaccharides was significantly higher than that of hot air-dried and vacuum-dried polysaccharides(P<0.05).Different drying methods had significant influence on the total sugar and sulfate and uronic acid contents of polysaccharides(P<0.05)and the total sugar and uronic acid content of dried polysaccharides was in the decreasing order:freeze drying>vacuum drying>hot air drying.On the other hand,the drying methods had no significant effect on the contents of proteins,amino sugars or moisture,pH or relative viscosity of polysaccharides(P>0.05).The dissolution time of freeze-dried polysaccharides was significantly shorter compared with those dried by two other drying methods(P<0.05).The polysaccharides from Trifolium repens L.contained a small amount of proteins or polypeptides,and exhibited a triple-helix conformation.The freeze-dried polysaccharides showed stronger reducing power and radical scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl and 2,2’-azino-bis(3-ehtylbenzothiazoline-6-sulfonic acid)free radicals than the two other dried samples(P<0.05).Therefore,freeze drying was the best drying method for polysaccharides from Trifolium repens L.because it maintained their antioxidant activity.