Study On Extraction, Separation And Fraction Of Polysaccharide From Lentinus Edodes(Berk.) Sing

Lentinus edodes(Berk) Sing fruiting body is rich in nutrition, it is not only appetizing, but also has many sanitarian functions. The polysaccharide of lentinus edodes(Berk.) Sing(or lentinan) as an important resources is widely used in food, medicine and health care industry. In this dissertation, the primary contents and results are as follows:1. A new method to determine the lentinan content in the mixture of lentinan and pectins was set up.Pectins is a kind of polysaccharide that is able to be solved in water, it always exists in the extraction solution of lentinan. A new method was established to determine glucose and glucuronic acid in sample solution, it can remove interference produced by glucose. In this method, the glucose and glucuronic acid were proved to have well plus character with model, and it was proved that this method is exact and credible.2. Extraction of lentinan from Lentinus edodes(Berk) Sing fruiting body with microwave method and traditional hot water method were studied.For traditional hot water method, through the study of different proportion of material and solution, extraction temperature and time, finally, the most rational conditions were comfirmed as follows: weight of material : weight of water = 1:20, temperature is 90℃, time is 3 hours, extraction rate of lentinan is 9.97 %; For microwave method, through the study of different proportion of material and solution, microwave power, extraction temperature and radiated time, finally, the most rational conditions were comfirmed as follows: weight of material : weight of water = 1:30, microwave power is 800 W, temperature is 80℃, time is 15 minutes, extraction rate of lentinan is 11.78 %. Through the comparison of these optimized methods, the results indicated that the microwave method has many advantages, such as higher extraction rate, lower energy consumption, less working time and etc. 3. Purification methods of lentinan was studied.First step of separation and purification: through the study of purification effects of lentinan with Sevage and Sevage-enzyme methods, it is found that Sevage-enzyme method had higher efficiency of removal protein, its rate of removal protein with one time is 92.9 %, the percentage of protein in lentinan sample is 19.8 %, it shows that the loss of lentinan is high. Therefor, a new method named CAS was exploited. It has CaCl₂ and ammonium oxalate reagents and processes of chelation, flocculation and sedimentation, its rate of removal protein with one time is 96.5 %, the percentage of protein in lentinan sample is 1.22 %.Second step of separation and purification: after the first step of separation and purification, the polysaccharide sample was purified ulteriorly with enzymatic decompounding, dialysis and adsorption with active carbon, and it was analysed with UV spectrum and IR spectrum, the results were proved that it was a kind of lentinan with structure of β-D-pyran glucan, and it didn't contain protein, nucleic acid, pectins and etc. The most rational conditions in these processes were: percentage of CaCl₂ is 22.2 %, percentage of ammonium oxalate is 1.6%, percentage of trypsin is 10 %, pH is 7.9, temperature of enzyme solution is 37°C, enzymatic decompounding time is 5 hours, dialysis time is 4 hours, quality percent of active carbon is six percent, the recovery of lentinan is 5.04 %.4. Fraction methods of lentinan were studied.With acetone as a medium, the organic solvent method was undertook in fraction experiments of lentinan. Two parts of different moleculare weight were obtained in 30% acetone solution and 50 % acetone solution, and their molecular weight were determined with viscometry, the one is 4.25×10⁵, the other is 0.88×10⁵.