Effect of the Enrichment of Corn Oil with - or -Tocopherol on Its Digestion Studied by H NMR and SPME-GC/MS; Formation of Hydroperoxy-, Hydroxy-, Keto-Dienes and Keto--epoxy--Monoenes in the more -Tocopherol Enriched Samples.

The aim of this study is the analysis of the digestion of corn oil, and of the effect of its enrichment with three levels of - and -tocopherol, by using, for the first time, H nuclear magnetic resonance (H NMR) and a solid phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS). The attention is focused on the hydrolysis degree, the degradation of oil's main components, the occurrence of oxidation reactions and main compounds formed, as well as on the bioaccessibility of oil's main components, of compounds formed in the oxidation, and, of - and -tocopherol. The lipolysis levels reached are high and show a similar pattern in all cases. The oxidation of corn oil components during digestion is proven, as is the action of -tocopherol as an antioxidant and -tocopherol as a prooxidant. In the more -tocopherol enriched samples, hydroperoxy-, hydroxy-, and keto-dienes, as well as keto-epoxy-monoenes and aldehydes, are generated. The bioaccessibility of the oil's main components is high. The compounds formed in the oxidation process during digestion can also be considered bioaccessible. The bioaccessibility of -tocopherol is smaller than that of -tocopherol. The concentration of this latter compound remains unchanged during the digestion of the more -tocopherol enriched oil samples.