Total Phenolic Compounds (TPC)
Total phenolic compound content was determined with a spectrophotometer (UV2450, Shimadzu, Japan) utilizing the sample preparation method that Günç Ergönül (2006) had used. Calibration curve was obtained using the standard solutions in different concentrations prepared from cafeic acid stock solution. 1 g of homogenized olive sample mixed with 5 mL of methanol:water (60:40) solution and shaked for 2 min. Then, it was centrifuged at 3500 rpm for 10 min. The supernatant was taken into a 10 mL tube filtering through a coarse filter paper. The supernatants obtained from the extraction which was performed two timeswere combined. and was filled with distilled water to the volumeline . Once the sample was well mixed, 0.1 mL was taken into 50 mL volumetric flask and 5 mL of distilled water and 0.5 mL Folin-Ciocalteu reagent were added. After 3 min, 1 mL of 36% Na2CO3 solution was added. Then, the sample solution was made up to the volume with distilled water. After the solution was kept in the dark for 2 h, the absorbance were measured at 725 nm wavelength using UV/VIS Spectrophotometer. The concentration values that correspond to the absorbance values were determined in the calibration curve for each sample and the results were calculated as mgCAE/100g olive considering the dilution factor (CAE: cafeic acid equlibrium).