Studies on the extraction and antioxidant properties of Pu Erh tea polyphenols

Pu Erh tea polyphenols was extracted by Microwave-assisted extraction,and optimized the extraction factors. At the same time,studied the ability for scavenging hydroxyl free radical (·OH) and DPPH· free radical (DPPH·) of the extracts.The effect of Microwave power,ratio of solvent to material and extracting time on yield of polyphenols were discussed.The Box-Behnken Design was applied to fit a response surface function.Scavenging of ·OH and DPPH· by the extract was studied.The optimal levels for obtaining 5.32% polyphenols were as follows:the Microwave frequency is 539 W,the ratio of solvent to material is 50∶1(V∶W),and the extracting time is 2.4 min.The hemi-inhibiting concentration of Pu Erh tea extract for scavenging 50% ·OH radical was 31.13 μg/mL,which is lower than the Green tea extract of 49.36 μg/mL.When the concentration of the extracts was up to 30 μg/mL,the ability of scavenging DPPH· free radical was almost at the same level.The Box-Behnken design can be used on the extraction of polyphenols from Pu Erh tea.Pu Erh Tea polyphenols has remarkable scavenging activity to ·OH and DPPH·.