The thermal decomposition of unsaturated fatty acids requires less energy than the decomposition of saturated fatty acids
(Kasprzycha-Guttman & Cozeniak, 1991). Using the study of the oxidation kinetics (Fig. 3) it was possible to determine the activation energy of the event by calculating the first 10% of mass loss associated with the oxidation of the samples. According to Kovalski, Ratusz, Miciula, and Krygier (1997), the thermal oxidation of lipids is an exothermic reaction that can be measured by enthalpy variations. In the present study the fat extracted from the cheese covered with rosemary leaves showed higher oxidation temperatures (To and Tp) as well as higher enthalpy values (DH). The 1H RMN results (supplementary materials) show that no structural modifications, suggesting that the antioxidant activity occurs due rosemary presence, demonstrated when the fat is subjected to thermal stress.