For the saturated fatty acids composition, a significant difference (p < 0.05) was observed between oils after 24 h of heating. The evolution of this composition is estimated at 25% and 5.5% in control and rosemary treated oils respectively at the end of the heating treatment. As mentioned above, the unsaturated fatty chains are highly sensitive to oxidation reactions, their oxidation induced a decrease in the rate of unsaturated fatty acids which will be converted into saturated fatty acids or even into trans fatty acids. In their studies, found that the addition of rosemary, sage extract and citric acid to the palm olein before frying retard effectively the thermal oxidation of the unsaturated fatty acids thus reducing the increase of saturated fatty acid especially the palmitic acid.