Study On Extraction And Preparation Of Green Tea Polyphenols

The thesis focused on extraction from low-end green tea, analysis, preparation and quality standard of tea polyphenols (TP) as follows:Systemic study on the extraction of TP was carried out. Firstly, the influence caused by some factors on TP leaching rate was studied. The orthogonal experiment showed that the optimum condition of leaching TP was: water as solvent, the ratio of tea and solvent was 1∶12, under 80℃, leaching 2 times and 30 minutes every time. Under the condition, the maximum leaching rate of TP reached 14.5% of tea. Secondly, the condition of purifying TP by depositing TP with metal ion was studied. Through repetitious experiment, the optimum condition of precipitation method was: ZnCl2 as precipitator, regulating pH value to 6.0 with NaHCO3, dissolving precipitation with HCl, extracting with acetic ether, refrigerating extract for removing dopants below 0℃, rotary evaporating, vacuum drying. It showed that the purity of TP was improved from 74.3% to 95.6%.On the basis of previous work, tea polyphenols was analyzed by high performance liquid chromatography(HPLC). Compared with standard samples, epigallocatechin gallate (EGCG), epicatechin gallate(ECG), epigallocatechin (EGC), epicatechin(EC) and fractionary coffein(CAF) were inspected out in TP sample and we quantitatively determined the contents. This method was convenient, accurate, fast, reliable and suitable for evaluating quality of tea polyphenols. According to property of tea polyphenols and demand of production, storage, transportation, tote and take, we decided to planish tea-polyphenols into tablet which contained high dose principal agent through powder material planish tablet immediately.The quality standard of TP tablet was investigated. The tablet had smooth faces, uniform colour, appropriate rigidity, low smash ratio, little fluctuate of tablet weight, short breakdown time. We not only determined the TP content of the tablet with its preparation by fertaron colourimetry, but also determined the main component EGCG content of the tablet by HPLC.The research work was very important to extract, analyze and prepare TP which is a natural and atoxic antioxidant.