干燥方式对聚合草多糖理化性质和抗氧化活性的影响

Effects of drying methods on physicochemical properties and antioxidant activities of polysaccharides from Symphytum officinale L.

【目的】研究不同干燥方式对聚合草(Symphytum officinale L.)多糖理化性质和抗氧化活性的影响,筛选聚合草多糖最佳干燥方式,为聚合草加工利用提供理论依据。【方法】提取聚合草多糖,利用热风干燥、真空干燥和冷冻干燥技术对其进行干燥后,测定不同干燥方式所得多糖的理化性质和抗氧化活性,分析干燥方式对聚合草多糖理化性质和抗氧化活性的影响。【结果】(1)不同干燥方式对聚合草多糖得率及总糖、蛋白质、硫酸基、糖醛酸含量和相对黏度有显著影响(P<0.05),由高到低依次为冷冻干燥>真空干燥>热风干燥。(2)不同干燥方式对聚合草多糖水分含量、pH和氨基糖含量无显著影响(P>0.05)。(3)聚合草多糖的溶解时间随温度的升高逐渐缩短,不同干燥方式对聚合草多糖的溶解时间有显著影响,其中冷冻干燥多糖的溶解时间显著短于热风干燥和真空干燥多糖(P<0.05)。(4)冷冻干燥聚合草多糖的还原力(1.0 mg/mL时为0.83)、DPPH·自由基清除率(0.4 mg/mL时为57.09%)和ABTS·自由基清除率(1.5mg/mL时为99.70%)均显著高于热风干燥和真空干燥多糖(P<0.05)。【结论】冷冻干燥法是获得高品质和高抗氧化活性聚合草多糖的较好方法。

【Objective】The effects of different drying methods on physicochemical properties and antioxidant activities of polysaccharides from comfrey(Symphytum officinale L.)were determined and the optimum drying technique was obtained to provide theoretical basis for the processing and utilization of comfrey.【Method】Hot air drying,vacuum drying and freeze drying technologies were used to dry polysaccharides from comfrey.The differences in physicochemical properties and antioxidant activities of polysaccharides from comfrey were compared.【Result】(1)Different drying methods had significant influence on yield,total polysaccharide content,protein content,sulfate content,uronic acid content and relative viscosity of polysaccharides(P<0.05),and they were in the order of freeze drying>vacuum drying>hot air drying.(2)Drying methods had no significant effects on moisture content,amino sugars content and pH of polysaccharides(P>0.05).(3)The dissolution time of polysaccharides from comfrey gradually decreased with the increase of temperature.Different drying methods had significant effects on the dissolution time of polysaccharides from comfrey.The dissolution time of polysaccharides drying with freeze method was significantly shorter than that with hot air and vacuum methods(P<0.05).(4)Polysaccharides drying with freeze method showed stronger reducing power(0.83 at 1.0 mg/mL)and scavenging capacities against DPPH·radical(57.09%at 0.4 mg/mL)and ABTS·radical(99.70%at 1.5 mg/mL)than polysaccharides drying with hot air drying and vacuum drying methods(P<0.05).【Conclusion】Freeze drying was the best method for obtaining high quality and antioxidant activities of polysaccharides from comfrey.