| 1. Structure, properties, 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. Rizhao green tea was used as material in this study. Both orthogonal experiment and single-factor experiment were used to study the effect of W/V rate, extraction time and temperature on the extraction result.The effect of tea granularity and stir were also studied. The optimized extraction programs are as follows:under the condition of stirring, extracted by 20 times distilled water at 70℃, and this extraction was devided into 2 times and each for 45min.Under this condition, the extraction rate of TP and TPS are 15.76% and 2.78%.3. In order to separate TP and TPS from the leach liquor, parallel experiment was used to study the effect of ethylacetate extraction times on the actual yield rate of TP, and the effect of ethanol volume on the actual yield rate of TPS. The optimized separation programs are as follows:the extract solution is concentrated to a solid content of 5%, extracted two times with the same volume ethylacetate, and the ethanol volume is 3 times of water. Under this condition, the actual yield rate of TP and TPS are 21.53%and 3.01%.4. Rizhao green tea crude polysaccharides were deproteinized by Sevag reagent, trichloroacetic acid and digallic acid. The results show that Sevag method has higher polysaccharides content, lower polysaccharides retention rate and lower efficiency, and has some poisonous solvent residual; digallic acid method has higher polysaccharides retention rate and lower deproteinization rate; the most effective method is trichloroacetic acid method. As the pH value of polysaccharides solution is 4.0 adjusted by trichloroacetic acid, the results are:the deproteinization rate 68.4%, the polysaccharides retention rate 66.8% and the polysaccharides content 72.5%.5. Rizhao green tea crude polysaccharides were decolorized by Hydrogen Peroxide and AB-8 resin.The best technical parameters are determined as follows: 1) Hydrogen Peroxide method:the Hydrogen Peroxide volume is 60% of the TPS solution, pH is 9.0, keeping warm at 50℃for 3h. Under this condition, the decoloration rate is 65.1%, and the polysaccharides retention rate is 76.4%.2) AB-8 resin method:pH is 4.0 adjusted by dilute hydrochloric acid, keeping warm for 1h while oscillating. Under this condition, the decoloration rate is 79.2%, and the polysaccharides retention rate is 58.5%.6. In order to get high purity EGCG, AB-8 resin and Sephadex LH-20 were used to purify crude TP in the initial stage and further stage. The results show that:1) Catechin Monomers are most adsorbed by AB-8 resin when in distilled water.The adsorption quantity of TP, EGCG and ECG is 63.08mg/g,33.87mg/g and 7.69mg/g. As the increasing of ethanol concentration, the adsorption capacity of AB-8 resin on TP and Catechin Monomers is falling, and the desorption capacity of absolute ethyl alcohol is the best.Dynamic elution is carried out on AB-8 resin column with absolute ethyl alcohol.The flow velocity is 1.0-1.5mL/min. The eluate containing EGCG and ECG is concentrated, and the content of EGCG is 78.32%.2) Ethonal with concentration of 50% and 75% were used to desorb Sephadex LH-20, and both of them had a great desorption rate difference on EGCG and ECG which is about 23%. But the desorption rate of 50% ethonal solution is lower than that of 75%, and the flow velocity of 50% ethonal solution is slow, not suit for operation. So 75% ethonal solution was chosen for eluting reagent. The eluate containing EGCG and ECG is concentrated and fed into the gel column, which is eluted by 75% ethanol solution with flow velocity 0.6mL/min. The content of EGCG is 94.76%. |
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