Study on pretreatment conditions of green-tea for extraction of tea polyphenols

Using low-end Se-enriched green tea produced by Ziyang county as experimental material,the optimal pretreatment conditions of green tea for extracting tea polyphenols were investigated by single factor and orthogonal test,according to the impurity extraction rate and tea polyphenols loss rate.The experimental results showed that the best ratio of green tea to water,extracting temperature,and extracting time were 1∶15(W∶V),25 ℃,and 20min with impurity extraction rate of 12.27% and tea polyphenols loss rate of 3.92%.When the pretreated green tea was extracted by water for 60 min at 85 ℃,crude product purity increased by 38.50%,while the content of caffeine reduced by 32.74% compared with the control.