桑叶粗多糖最佳提取工艺研究

Study on the Optimum Extraction Process of Mulberry Leaf Polysaccharide

为探究桑叶粗多糖最佳提取工艺,利用正交试验设计对桑叶粗多糖的提取工艺进行优化。以桑叶粗多糖得率为评价指标,以加水倍数、煎煮时间、煎煮次数为考察因素,设计3因素3水平正交试验,采用苯酚一硫酸比色法进行桑叶粗多糖含量测定,比较得出桑叶水提物的最佳制备工艺,并在此基础上考察不同浓度乙醇对桑叶粗多糖提取的影响。结果显示,煎煮次数对桑叶粗多糖提取率影响最大,当加水倍数为25倍,煎煮时间为2h,煎煮2次时桑叶水提物中桑叶粗多糖提取率最高,为4.94%。但结合影响因素分析,最终确定桑叶水提物的最佳提取工艺为加25倍水,煎煮2h,煎煮3次。乙醇浓度对桑叶粗多糖的含量及得率影响很大,70%乙醇醇沉所得水提物中桑叶粗多糖质量最大,40%乙醇醇沉所得桑叶粗多糖含量最高,平均含量达41.5%,显著高于其他乙醇浓度(P<0.05),提示乙醇浓度越高,桑叶粗多糖含量越低,但得率越高。桑叶粗多糖最佳提取工艺为:加水倍数为25倍,煎煮时间2h,煎煮3次,采用70%乙醇醇沉。

The experiment was conducted to study the best extract process of mulberry leaf poly-saccharide,three factors and three levels orthogonal test was designed to optimize the extraction process.Three factors were considered,including ratio of solid to liquid,decoction time,the time of extracting and the yield of mulberry leaf polysaccharide was determined with phenol-sulfurie acid colorimetry as the evaluate index.Meanwhile,the influence of ethanol concentrations on mul-berry leaf polysaccharide extract was studied.The results showed that decoction times could grea-test affect the extraction percent of the polysaccharides.The extraction percent of polysaccharide was the highest （4.94%）when the rate of solid to liquid was 25,the time of extracting was 2 h and decoction times was 2.While the most appropriate process was 25 times for the rate of sdid to liquid,2 h for extracting and decoction times was 3 ,considering with practical situations.The con-centration of ethanol would significantly affect polysaccharides yield and purity.When the concen-tration of ethanol was 70%,the yield of mulberry leaf polysaccharid was highest.When the con-centration of ethanol was 40%,the content of mulberry leaf polysaccharide was highest （41.5%）, significantly higher than other ethanol concentration （P〈0.05）.It suggested that the higher the ethanol concentration,the lower the polysaccharide content,but the higher the yield.The opti-mum extraction of mulberry leaf polysaccharides were that the rate of solid to liquid was 25,ex-tractign for 2 h,decoction 3 times and 70% ethanol precipitation.