Optimization of extraction technology of keemun black tea polyphenols and its composition identification

The extraction technology of black tea polyphenols was optimized using keemun black tea as material.The effect of ethanol concentration,extraction temperature,extraction time,solid-liquid ratio,p H on extraction yield was investigated by single-factor experiment and the extraction technology was further optimized by orthogonal experiment. The optimum extraction parameters were as follows :ethanol concentration 60%,extraction temperature 70 ℃,extraction time 2.5 h,and solid-liquid ratio 1∶50(g/m L). The extraction yield was(214.23±6.29) mg/g after the second extraction. In addition,UPLC-DAD was applied to identify keemun black tea polyphenols. Results showed that the main components of keemun black tea polyphenols were gallic acid,(-)-Gallocatechin(GC),(-)-Epicatechin(EC),(-)-Catechin gallate(CG),(-)-Epicatechin gallate(ECG),(-)-Epigallocatechin gallate(EGCG),Theaflavin(TF1),Theaflavin 3-gallate(TF3G),Theaflavin 3 '-gallate(TF3′G) and Theaflavin 3,3'-digallate(TF33′G).