The evaluation of the fatty acid profile of fats and oils, such as soybean oil, that are subjected to heat can provide important data concerning the changes to each fatty acid during this process. Some studies have shown that the alteration of vegetable oils is influenced by the amount of unsaturated fatty acids present, and that the loss of a-linolenic acid(C18:3) can vary from 20 to 25% (Juárez et al. 2005). Initially, samples revealed linoleic acid (C18:2) to be the main fatty acid, corresponding to more than 50% of the total fatty acids identified (Table 3). Kim et al. (2010) also found that linoleic acid is the major fatty acid in soybean oil, representing 50.5%. According to the Codex Alimentarium, soybean oil should contain between 4.5 and 11% a-linolenic acid. In this study, the oils were made up of between 3.81 and 5.64% of this fatty acid at 0 h. On the other hand, samples heated for 20 h had values below those recommended by the Codex Alimentarium