Influence of different extraction methods of tea polyphenols on proportions of catechins

The catechins composition of tea polyphenols with different extracted methods was analysed by HPLC. The aim is to compare the extraction effect of water-extracting and alcohol-extracting method, the purification effect of solvent extraction and ionic precipitation method. The results indicated that organic solvent extraction method can improve the extraction rate of catechins, especially can increase the content of estered catechins. In the technic of organic solvent extraction, the total content of catechins can effectively be increased by using alcohol extraction. Ion precipitation can enhance the content of gallocatechins, while organic solvent extraction can raise the contents of catechins, EC and estered catechins.