Study On The Separation And Purification Of Tea Polyphenols And EGCG

1.Extraction and analysis methods,as well as the application status of TP, Catechin Monomers and TPS were summarized.Besides,all the advantages and disadvantages of the mentioned extraction and analysis methods were compared respectively.2.Both single-factor experiment and orthogonal experiment were studied to determine the best technical parameters.The best parameters are as follows:1)Tea granularity 22～80 mesh,Ratio of Materials(g)to Liquid(ml)=1:20,Temperature 70℃,Extract two times and each for 45min,under the condition of stirring.Then combine the extract solutions;2)The extract solution is concentrated to a solid content of 5%;3)Extract two times with the same volume ethyl acetate and each for 60rain.Combine the extract solution;4)Decompression distillation at 50℃;5) Freeze-drying at -40℃and vacuum.3.In order to improve the extraction rate,effects of different assistant methods on the solvent extraction of TP were studied.Results show that the extraction rates of assistant methods are higher than those of traditional solvent extraction,and microwave-assisted extraction is the best.Extraction rate,actual yield rate and purity of TP are 79.80%,23.21%and 83.71%respectively,by extracting twice at midrange microwave power and 4min.4.DM-130 macroporous adsorption resin was used to purify crude TP.Both the adsorption and desorption capacities of the resin were studied.Eventually,the best technical parameters are determined as follows:1)Feeding concentration of TP solution is 10mg/ml;the velocity of flow is 4ml/min;2)Elute with 80%(V/V)ethanol solution,and velocity of flow is 2ml/min;pH=3.0.The content of TP rises to 95% from 76.85%.5.Sephadex LH-20 was used to purify EGCG.Both the adsorption and desorption capacities of Sephadex LH-20 for EGCG were carefully studied.It mainly involved the following aspects:1)The effect of solvent Concentration on the adsorption and desorption capability was studied.As far as EGCG and ECG are concerned,the optimal adsorption solvent is distilled water;the optimal desorption solvent is anhydrous ethanol,while the optimal desorption solvent used to separate EGCG and ECG is 40%(V/V)ethanol solution.2)Results of dynamic adsorption and elution show that the optimal technics is a combination of static adsorption and dynamic elution.Static adsorption is carried out firstly and then followed by dynamic elution.The eluate velocity is 0.6～0.8ml/min.The eluate containing EGCG and ECG is concentrated and fed into the gel column,which is eluted by ethanol solution whose volume concentration is 40%.Thus EGCG of high purity is obtained;3)The circulatory longevity of Sephadex LH-20 was particularly studied. Results show that adsorption capacity and desorption rate vary slightly with the use times when circulatory times is no more than 5.So Sephadex LH-20 is suitable for purifying Catechin Monomers.6.TP is chemically unstable and can also be easily oxidized.Taken this into account,the stability of TP under different storage conditions was studied.The optimal storage condition is dark and refrigerated Storage(—10℃).