Technological Study On Preparation Of Tea Catechins Which Is Poor In Ethyl Acetate And Rich In EGCG

Tea catechins,as an prominent active subtance of tea,as representative of tea processing products,whose preparation has been much-talked-about. Based on previous study,the thesis is hope to find the optimal control conditions to produce tea catechins which is poor in ethyl acetate and rich in EGCG through analysing extraction conditions and column chromatography separation condition experiment.The processing procedure is as below:With the broken pieces of green tea which hasn't been fully utilized as raw materials→Extraction→Centrifugation→Column chromatography separation→enrichment→Spray drying.Specific parameters are:ethyl acetate<14ppm,tea catechins≥70%,EGCG≥45%,Caf<2%,yield coefficient> 10%.The main conclusion is as below:(1)Best extracting agent to get tea polyphenol and EGCG is water,the content of extracting of tea polyphenol is 19.786%.Tea catechins by the same proposed column chromatography separation condition with all sorts of extracting agents.Compared to the others,tea catechins with water extraction is poorer in caffeine, more rich in total catechin.(2)The premium condition to extract tea polyphenol and EGCG is confirmed as: 80℃temperature, extract time 80mins, tea leave/water ratio 1:20, influence of the three factors in the relationship between primary and secondary is:T>t>m/V,namely extraction temperature> extraction time>tea leave/water ratio,under such circumstances, the extraction content of tea polyphenol is 20.16%,EGCG is 6.108%.(3)Selecting ion exchange resin—rohmhaas resin, weak polarity adsorption resin—AB-8 and polarity adsorption resin—polyamide resin, comparing the selective adsorption of catechins and elution effect, the experiment results showed that the best is polyamide resin.Meanwhile,the experimental analysis on the efficiency of polyamide resin showed that column efficiency to achieve the best condition in three times.(4)The experimental analysis of the elution agents which in the influence of catechins content showed that:To ensure efficient recovery of tea compositions,we should firstly with 1.25 BV 25% ethylalcohol, then with 1.3 BV ethyl acetate to elution,tea catechins and EGCG content of the finished product are relatively higher, Caf<2%, and the rate reached 10.21%.(5) GC detection and analysis showed that the residue levels of ethyl acetate is in the average of 6.05ppm,lower than the international safety standards.(6)The experiment conclusion in labs were verified and amplificated by workshop,the resules showde that the EGCG and total catechin were all declined, but all>10%,GC detection and analysis showed that the residue levels of ethyl acetateis is in the average of 5.93ppm,lower than that in the labs,also lower than the international safety standards.