Six refined olive oil samples were characterized to have wide ranges of compositional indicators (the ratio between monounsaturated and polyunsaturated fatty acids = 3.9 – 9.6; peroxide value = 1.3 – 7.0 meq/kg; acid value = 0.4 – 0.6 mg/g; total tocopherols = 150 – 459 mg/kg; total phenolics = 11 – 39 mg/kg). Oxidative stability index (OSI) and frying stability time (the time required to reach a total polar compounds, TPC, of 25%, a conjugated diene value, CDV, of 25 mmol/l, and a carbonyl value, CV, of 47 μmol/g) of the olive oils were monitored under two thermal (Rancimat at 110 – 140 ºC) and frying (at 180 ºC) processes, respectively. The values of OSI ranged from 7.1 h to 16.9 h at 110 ºC, which significantly decreased to 0.9 – 1.9 h at 140 ºC. Frying stability times were calculated to be 38.3 – 56.6 h, 25.6 – 64.1 h, and 32.4 – 55.3 h in terms of TPC, CDV, and CV, respectively. The greatest correlations (R2 ≥ 0.97) were obtained between the OSI at 110 ºC and the frying stability times. The CV-based frying stability times provided the highest correlations at all temperatures used in the thermal process.

Keywords