The effect of olive leaves and their harvest time on radical scavenging activity and oxidative stability of refined olive oil

Abstract

The antioxidant role of olive leaves obtained from Adana Topagi, Adana Yerli, Domat and Gemlik cultivars during olive ripening were investigated and compared to commercial olive leaf extract (OLE) as well as butylated hydroxyl toluene (BHT) and butylated hydroxyl aniline (BHA) as synthetic antioxidants. The results showed that total phenol contents of OLEs reduced 44 to 63% during ripening. OLEs, irrespective of cultivar and harvest date were found to be good sources of radical scavengers (P<0.05). The radical scavenging activity of OLEs at 100 or 200 μg/g were higher than BHT (P<0.05) and similar or lower than BHA (P≥0.05). The addition of Domat and Adana Topagi OLEs at 100 or 200 μg/g to refined olive oil increased oxidative stability and caused to extracts to show better activity than commercial OLE but lower or similar activity than that of BHT and BHA (P≤0.05) during different harvest times. BHA and BHT were the most effective antioxidants employed to delay the bulk oil oxidation but Domat and Adana ...