Studies On New Technology Of Preparation Of Green Tea Catechins

As the most bioactive components of green tea, catechins' health-protection and pharmaceutical effects have been used in many fields. EGCG, the main component of catechins, has received by far the most attention in the studies. Although there are many ways to prepare tea catechins, the solvent extraction and the iron-precipitation are mainly applied in the industrial technology.On the basis of former experimental results, the high-new technology(column chromatography and ceramic microfiltration membrane) is mentioned in this paper to prepare the specified catechin products such as GTC-70 and GTC-90 whose content of EGCG is high by using the raw materials of green tea and crude catechin product.The applied results of the ceramic membrane technology show that the maximum flow is obtained for the green tea extraction with the ceramic membrane of 0.2 m pore size, the solids and high-molecule substances are cut off to different degrees, the appropriate operating conditions for the process obtained are respectively 0.3 MPa for transmembrane pressure and 45 C-50 C for temperature, dialyzing the pore size of membrane with deiron water is of advantage for the recovery of flow flux in the later process, cleaning it with NaOH and NaClO can also recover the flow flux obviously after the operation.Selection of adsorption for catechins and caffeine is different according to resins. Some resins adsorb catehcins selectively from the green tea extraction with hydrogen bond, while nonpolar macroporous adsorption resins adsorb catehcins through interaction of van der waals force, so their selection ability is comparatively poor.When using green tea as raw material, it is difficult to prepare the qualified decatechin product of GTC-70(EGCG>40) which is eluted with 80% ethanol directly after being adsorbed by A resin. If it is eluted with low concentration gradient ethanol, the content of total catechins and EGCG would be improved andsimple catechins and caffeine would be reduced. In this way, two kinds of catechin products can be obtained which constituents and specification are different.When using crude catechin product extracted by ethyl acetate as raw material, the constituents of crude catechin product would be separated preliminarily if it is eluted gradiently with compound elution after adsorbed by B resin. In this way, three catechin products are gained, and product of GTC-90(EGCG>65) is at the range of 30%-40% concentration, which is used for API(Active Pharmaceutical Ingredient).The products can meet the different requests of expected production cost and quality according to the above methods in the pilot plant.