Autoxidation products of normal and genetically modified canola oil varieties determined using liquid chromatography with mass spectrometric detection

Normal, high stearic acid and high lauric acid canola oil varieties were he ated in the presence of air to allow autoxidation to occur. After the react ion, the oils were analyzed using a non-aqueous reversed-phase high-perform ance liquid chromatographic separation followed by detection using atmosphe ric pressure chemical ionization mass spectrometry. Oxidized products were separated and identified. The major autoxidation products which remained in tact were epoxides and hydroperoxides. Two classes of epoxy triacylglycerol s (TAGs) were formed. One class with the epoxy group replacing a site of un saturation and one class adjacent to a site of unsaturation, as was previou sly reported for model TAGs. Intact oxidation products resulted mostly from oxidation of oleic acid, while oxidation products of linoleic and linoleni c acid chains decomposed to yield chain-shortened species. Both neutral and polar chain-shortened products were observed. Polar chain-shortened decomp osition products eluted at very short retention times and required a differ ent chromatographic gradient to separate the molecules. This class of molec ules was tentatively identified as core aldehydes. The high stearic acid ca nola oil yielded more intact oxidation products containing stearic acid, as expected. The high lauric acid oil produced intact oxidation products whic h contained lauric acid. (C) 2001 Elsevier Science B.V. All rights reserved .