Effect of the Enrichment of Corn Oil With alpha- or gamma-Tocopherol on Its In Vitro Digestion Studied by 1H NMR and SPME-GC/MS; Formation of Hydroperoxy- Hydroxy- Keto-Dienes and Keto-E-epoxy-E-Monoenes in the More alpha-Tocopherol Enriched Samples

摘要

The aim of this study is the analysis of the in vitro 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 in vitro 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 in vitro 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 in vitro digestion of the more -tocopherol enriched oil samples.