Determination of Optimum Ethanolic Extraction Conditions and Phenolic Profiles of Thyme, Mint, Uckun, Grape Seeds and Green Tea Waste Fiber

The objective of this study was to investigate the effect of different ethanol ratios inextraction solvent as well as the antioxidant properties of five plants. Thyme, mint, uckun, grapeseeds and green tea waste fiber was analyzed to determine total phenolic content (TPC) andantioxidant activity by ABTS and DPPH radical scavenging activity assays. Individual phenoliccomponents were analyzed with reverse phase high performance liquid chromatography (HPLC).TPC varied significantly from 2.00±0.27 to 172.68±0.19 mg GAE g-1 dw depending on the plant typeand ethanol ratio of the solvent. The effect of ethanol ratio also varied among different plants. HPLCanalysis was performed for the extracts showing highest antioxidant activity, and green tea wastefiber (699.89 mg 100 g-1 dw) had the highest concentration of phenolic compounds overall, whilemint (173.67 mg 100 g-1 dw) had the lowest amount. Correlations between TPC and antioxidantactivity was significant which is comparable to the previous report.