The relationship between fatty acid compositions and thermal stability of extra virgin olive oils

Background: Fatty acids are one of the most important compounds in edible oils. Further, the stability of oils depends on the composition of fatty acids. So, this study was conducted to investigate the effect of fatty acid composition on the oxidative stability of extra virgin olive oils during the heating process.

Methods: In total, eight samples of extra virgin olive oil were studied. To evaluate their thermal stability, the oils were heated at 120 ° C for 4 h and  sampling was carried out in 2-hour intervals. Then, fatty acid composition, peroxide value, anisidine value and totox value were evaluated according to Iranian national standards.

Results: Results showed a significantly direct correlation between Palmitoleic acid and Totox index in the second (r=0.786) and fourth hours (r=0.762), and between linoleic and Totox index in the second (r=0.643) and fourth hours (r=0.786). However, there was a significantly inverse relationship between oleic acid and Totox index in the fourth hour
(r=-0.833).

Conclusion: Result indicated that linoleic and Palmitoleic acids had a reducing effect on thermal stability of extra virgin olive oil after the second hour. But, Oleic acid caused a positive effect on thermal stability after the fourth hour. Thus, it is concluded that unsaturated fatty acids especially oleic acid affect the thermal stability at final hours.