Effect of Biophenols on Olive Oil Stability Evaluated by Thermogravimetric Analysis

Virgin olive oil stability to autoxidation is mainly due to phenolic compounds naturally occurring in it, but contrasting data have been published on the effectiveness of the same antioxidant compounds. With thermogravimetric analysis (TGA) it is possible to have an estimation of oil resistance to oxidation, having a measure of weight gain percent due to reaction of sample with oxygen during the oxidation, and of initial and final oxidation temperatures. The following samples were examined: virgin olive oil, olive oil, and olive oil spiked with different amounts of some antioxidants. Tested phenols were p-HPEA, 3,4-DHPEA, 3,4-DHPEA-EA, caffeic acid, oleuropein, and, moreover, BHT and BHA. Data showed that natural antioxidant addition (especially oleuropein, 3,4-DHPEA, and 3,4-DHPEA-EA) could extend the olive oil shelf life and could protect oil from decomposition naturally occurring during thermal treatments (such as cooking process).