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| A new extraction technique, ultrahigh pressure extraction, was used to obtain antioxidants from green tea. The response surface methodology was employed to optimize the extraction process. The effects of ethanol concentration (33.2-66.8 %), pressure (281.8-618.2 MPa) and liquid/solid ratio (11.6-28.4 mL/g) on the total phenolic content and DPPH free radical scavenging activity were investigated. ANOVA showed that second order polynomial models produced a satisfactory fitting of the experimental data with regard to total phenolic content (R2 = 0.9996, P<0.0001) and antioxidant capacity (R2 = 0.9986, P<0.0001). The optimal condition determined was as follows: ethanol concentration 50%, pressure 490 MPa and liquid/solid ratio 20 mL/g. Under this condition, the maximum total phenolic content and antioxidant activity of 583.8±0.9 mg/g DW and 85.6±0.7% could be achieved, respectively, which were well matched with the predicted value. |
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| Keywords:ultrahigh pressure extraction; total phenolic content; antioxidant activity; response surface methodology; green tea |
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