Studies On The Green Efficient Extraction And Separation Of Tea Catechins EGCG

Tea catechins are the main ingredients in green tea. Due to their antioxidant ability and the capability to remove free radicals, more and more importance is attached to them. The epigallocatechin gallate has more active and a greater demand than other catechin components. The extraction and purification of esterified catechins and the separation and preparation of epigallocatechin gallate by resins was adopted in the experiment, which ameliorates the conventional proeess of extraetion and purification Epigalloeatechin gallate. Extration, adsorption and desorption by macroporous adsorption and crystallization were used during the process from instant green tea. High purity of EGCG produet was gained in the proeess. The operation steps of experiment and magnifying test were as ofllowed:1. Extraction technologyBased on the factors of temperature, time and number, both single-faetor experiment and orthogonal experiment were studied to determine the best technical parameters.The best parameters are as follows:at80℃with70%ethanol extraction, etareted for25min and repeated three times.2. Enrichment of esterified catechinsMacroporous adsorption resin was used for the enrichment of esterifiied catechins from green tea powder. LX-16was selected from four macroporous adsorption resins by evaluating the adsorption and desorption capacity, investigating velocity curve of static adsorption, adsorption isotherm, the dynamic sorption and alcohol gradient elution. The result showed that the LX-16has better adsorption selectivity for the esterified catechins. The purity of percent could reach65.2%form7.3%and the recovery was more than80%with gradient elution.3. Purification process of epigallocatechin gallateThe adsorption and desorption capacity of four kinds of MARs were evaluated, and desorption effect of different concentration of alcohol were analyzed. And then after crystallization EGCG crystals was precipitated. The result showed that the AB-8has better adsorption selectivity for the epigallocatechin gallate. The purity of percent could reach92.65%form54.41%and the yield was more than93.38%with10%alcohol elution.4. CrystallizationThe purity of EGCG would be improved by crystallization. The concentration of crystallization solution, time and temperature were exmined during the process of crystallization. The optimum condition of crystallization:40%solution, at4℃for4days. The purity of EGCG was95.60%.The poreess of rextracting and puritying EGCG is simple and short-cycle.The technology is valued as a new technology to generalize in producing high-purified EGCG, which can be used in the industrial production in the future.