Study On The New Technics Of Polyphenol Extraction And EGCG Purification

A new technics of extraction and separation was adopted in the experiment, which ameliorates the conventional process of extraction polyphenols and purification Epigallocatechin gallate (EGCG). Fresh old age tea leaves (Camellia Sinensis) used in the expeiment were boiled to kill the enzymes. Negative pressure cavitation suspension solid to liquid technology was used to effectively strengthen polyphenols extracting. Membrane separation system, chromatography of polyamide and negative press cavitation suspension solid to liquid were used during the purification process. High purity of EGCG product was gained in the new process. The optimum conditions of experiment and magnifying test were as followed:1. The optimum process of extractionFresh old age tea leaves were boiled to kill enzymes firstly. The optimum condition of killing enzymes: at 90℃ for 7min. The optimum extraction conditions: ratio of liquid to material 10: 1, extract for 3min. Meanwhile, the cavitation effect, clipping effect and disturbance effect make the bubble transient disintegration and negative pressure collapsing. Method of neagative pressure cavitation suspensinon solid-liquid was used to effectively strengthen EGCG extracting. The optimum conditions of strengthening extraction: ratio of liquid to material 9:1, extracted for 25 min and repeated one time. The extraction yield of EGCG was 4.56%.2. The optimum process of purificationThe extraction solution was separated by membrane system. The experiment of chromatography of polyamide indicated the large adsorption capacity was 25mg/g polyamide. The content of EGCG was 53.61% and the desorption ratio was 68.23%. The deionized water and 5% ethanol were used to elute the caffeine. Then 80% ethanol was used as elution. After the treatment EGCG content was increased to 55.37% and the recovery was 98.13%. The elution was concentrated and extracted by EtoAc negative pressure cavitation suspension of liquid to liquid. The optimum condition was: liquid to liquid 1:1, ventilation equivalent flow rate 3 BV/h, extracted for 20min and two times.During this purification process, the EGCG content was 55.37% and the recovery ratio was 53.58%.3. Silica gel column chromatography was used to further purify. The large adsorption capacity was 37 mg per silica gel. The optimum condition was as followed: 300~500 mesh silica gel, elution solvent was EtoAc: petroleum: formic acid 5.8: 7: 1, flow rate 4mL/min.The EGCG content of the final product was 98.12%, the yield was 32.53% and caffeinecontent was less than 0.1%. In the experiment, EGCG content and yield were 11.25% and 2.01%, and were both higher than recent process.The process for extracting and purifying EGCG is simple, short-cycle and low cost. 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.