Study On Extracted, Separation, Purification And Characters Of Polysaccharide From Longan Fruit Pericarp

Longan(Dimocarpus longanLour) has been used as traditional medicine and food,which has high edible and pharmacological value.Longan fruit pericarp makes up 14%to 22%of longan fruit,but longan fruit pericarp was not researched and exploited well at present.Using longan fruit pericarp drying at 40℃as raw material and polysaccharide as index,the processing parameters of hot water,microwave,and ultrasonic wave-assisted extraction technology were studied,the best method and process parameters of longan polysaccharide was determined finally.The rough extracted polysaccharide was deproteinized and decolored,which was isolated and purified by DEAE-52 cellulose ionic column and Sephadex-G200 gel column,and then the characters of the purity polysaccharide were also studied.The above studies can provide some suggestions for application and exploration of longan fruit pericarp and some theory for the functional study of polysaccharide.The main contents and results are shown as follows:(1) The method of sulfuric acid-anthrone was used to mensurated of longan fruit pericarp polysaccharide.The method is suitable for the experiment with convenient,accurate,stable and high recycle ratio.(2) Using longan fruit pericarp as raw material,hot water,microwave,ultrasonic wave-assisted extraction technology for longan fruit pericarp polysaccharide were compared;Based on the single factor test,the response surface analysis was used to optimize the process parameter. The results showed that the content of polysaccharide extracting by means of water extracting was up to 1.29%when temperature was 59℃,extraction time was 3h,liquid-solid ratio was 35:1,the content of polysaccharide extracting by means of microwave assisted extracting was 1.98%when temperature was 68℃,liquid-solid ratio was 35:1 and time was 4.7min,and he content of polysaccharide extracting by means of ultrasonic wave assisted extracting was1.42%when temperature was 57℃,time was 10.5min,liquid-solid ratio was 26:1 and ultrasonic power was 100W.Compared with the three extraction methods,the microwave assisted extraction technology is high yield and efficient.(3) Sevag,trichloroacetic acid and enzyme methods were used for deproteinization;The results showed that the enzyme method has the best effect.The deproteinization rate was 80%and loss rate of polysaccharide was 27%when deproteinizating by papain.(4) Effects of five kind of macro-porous resins,hydrogen peroxide and activated carbon on decoloring were studied;The result showed that resin D900 has a good effect.By the means of single factor and orthogonal test,we can get the best parameters as follows:temperature was 40℃, time was 2h,pH was 4.5 and dosage was 7.5g.Under the optimal extracting parameters,the decolored ratio was 84.1%,and the loss ratio of polysaccharide was 64.2%.(5) After deproteinization,decoloration and removed small molecular,the polysaccharide LP-1 was separated by DEAE-52 column chromatography.The result showed that the distilled water was better than NaCl solution with concentration of 0.1mol/L,0.3mol/L and 0.5mol/L.Number 8 to 18 cuvettes of eluent were collected for further study.After concentrated and settled by ethanol,we got the polysaccharide named LP-2.(6) LP-2 was separated and purified with Sephadex G-200 column chromatography;The single symmetrical peak showed that the polysaccharide LP-3 was pure.(7) Characteristic reactions of LP-3 were discussed,the results showed that it was non-starch polysaccharide without protein or polyphenol material,but it contains uronic acid.The ultraviolet spectra results showed that LP-3 did not contain nucleic acid or protein.