Effect of gamma irradiation on the total antioxidant capacity and sterols contents in Kaissy variety extra virgin olive oil

Twenty Kaissy variety extra virgin olive oil samples collected from research centre field near Damascus were analyzed by gas chromatography using a flame ionization detector. Fifteen sterols fractions were identified and determined their concentrations: cholesterol, brassicasterol, 24-metilencholesterol, campesterol, campestanol, stigmasterol, ∆7- campesterol, ∆5.23-stigmastadienol, clerosterol, ß-sitosterol, sitostanol, ∆5-avenasterol, ∆5.24-stigmastadienol, ∆7-stigmastenol and ∆7-avenasterol. The total average sterol amounts were in the range 43 to 1240 mg/kg. It has been observed that the concentrations of sterols are consistent with the International Olive Council, IOC Regulations, except the ∆7- stigmastenol which is higher (≥ 0.7%) than the IOC regulation (≤ 0.5%). This might be due to the typical environmental and soil type since Kaissy variety usually grows in red clay soils besides the genetic property classification as more resistant variety and less susceptible toward infection in dry area The total antioxidant components of extra virgin Kaissy variety olive oil extracts were measured for oil immediately pressed and after one year of storage for the average of three samples measurements as hydrophilic and hydrophobic existence species using photochemiluminescence, PCL assay. It has been found that, the total average antioxidant capacity value of immediately pressed Syrian virgin olive oil and after one year of storage was at (179.26, 28.63) and (128.21, 11.92) nmol, as hydrophilic and hydrophobic, respectively. The impact of gamma irradiation sample on the total antioxidant and sterols contents has been shown. The total antioxidants were decreased as the result of storage and after irradiation at three kGy dose in comparison with the control.