Material
Refined soybean oil without the addition of synthetic antioxidants (TBHQ and citric acid) was obtained from Cargill Agrícola S/A (Uberlândia, Minas Gerais, Brazil). The synthetic antioxidant, TBHQ, was supplied by Danisco S.A. time intervals of 0, 10 and 20 h and collected in flasks in the presence of inert gas (N2) and stored at -18C until the time of analysis.