超声-微波协同提取柚子皮多糖工艺优化及单糖组成、结构和抗氧化活性分析

Optimization of ultrasonic-microwave extraction process of pomelo peel polysaccharide and analysis of monosaccharide composition,structure and antioxidant activity

以柚子皮为原料,采用超声-微波协同提取技术提取柚子皮多糖,优化最佳提取工艺,对其进行脱色、脱蛋白处理,对其单糖组成、结构和抗氧化活性进行分析。结果表明,超声-微波协同提取柚子皮多糖最佳工艺为:微波功率400 W,提取时间34 min,液料比39∶1(mL∶g),提取液pH 9.0,多糖得率为10.41%。紫外光谱分析表明无蛋白质及核酸残留,凝胶渗透色谱法测定柚子皮多糖平均分子质量为2.4×10^4 Da。液相色谱-质谱联用仪测定结果表明,柚子皮多糖是一种酸性杂多糖,由甘露糖、鼠李糖、葡萄糖醛酸、半乳糖醛酸、葡萄糖、半乳糖、阿拉伯糖组成,摩尔比为0.502∶0.960∶0.295∶6.331∶40.673∶10.732∶7.923。扫描电镜和红外光谱分析表明,柚子皮多糖主要为不规则碎片结构,伴有小的不规则颗粒,碎片表面粗糙,所得多糖呈不规则形状,表明柚子皮多糖具有非晶态结构,为吡喃型糖苷环骨架。抗氧化活性结果表明,柚子皮多糖具有较好的自由基清除效果,在质量浓度为1.0 mg/mL时,对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、羟自由基和2,2′-联氮-双-3-乙基苯并噻唑啉-6-磺酸[2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS]自由基清除率分别为55.58%、46.32%、40.25%。该实验结果为柚子皮多糖的进一步分离纯化、结构解析、生物活性研究及开发具有潜力的功能性食品提供依据。

In this study,pomelo peel was used as raw material,ultrasonic-microwave collaborative extraction technology was used to extract pomelo peel polysaccharide.The optimal extraction process was optimized in response to the surface.Decolorization and deproteinization of pomelo peel polysaccharide were carried out,and their structure and antioxidant activity were analyzed experimentally.The results showed that the optimum process of ultrasonic-microwave collaborative extraction of pomelo peel polysaccharide was as follows:Microwave power 400 W for 34 min with liquid-solid ratio 39∶1(mL∶g)at pH 9.0.Under above conditions,the yield of polysaccharide reached 10.41%.Moreover,Uv-spectrum analysis showed that there was no protein and nucleic acid residue.Gel permeation chromatography was used to determine the average molecular weight of pomelo peel polysaccharide to 2.4×10^4 Da.The results of LC-MS showed that the polysaccharide was acid heteropolysaccharide which consisting of Mannose,rhamnose,glucuronic acid,galacturonic acid,glucose,galactose,arabinose with a molar ratio of 0.502∶0.960∶0.295∶6.331∶40.673∶10.732∶7.923.Furthermore,scanning electron microscope and infrared spectrum analysis showed that the polysaccharide was mainly irregular fragment structure,accompanied by some small irregular particles,the surface of the fragment was rough,and the resulting polysaccharide presented irregular shape,indicating that the polysaccharide had amorphous structure and was a pyranoid glycoside ring skeleton.The results of antioxidant activity showed that pomelo peel polysaccharides had better free radical scavenging effect,and the scavenging rates of DPPH free radical,hydroxyl free radical and ABTS free radical were 55.58%,46.32%and 40.25%,respectively,when the mass concentration was 1.0 mg/mL.The results of this experiment provide a basis for further separation and purification,structural characterization,bioactivity research of pomelo peel polysaccharides and development of functional food with potential.