Modeling of alpha-tocopherol loss and oxidation products formed during thermoxidation in triolein and tripalmitin mixtures.
The degradation of alpha-tocopherol and the formation of alpha-tocopherol and triacylglycerol oxidation products at high temperatures (150-250 degrees C) over a heating period (0-4 h) for a model system ranging between triolein and tripalmitin were modeled by use of an experimental design. The oxidation products of alpha-tocopherol formed under these conditions were alpha-tocopherolquinone (1 .4-7.7%) and epoxy-alpha-tocopherolquinones (4.3-34.8%). The results indicate a very high susceptibility of alpha-tocopherol to capture peroxyl radicals upon oxidation, leading to the formation of polar tocopherol oxidation products. Both alpha-tocopherolquinone and epoxy-alpha-tocopherolquinones were not stable upon prolonged heating and were further degraded to other unknown oxidation products. The kinetics of alpha-tocopherol oxidation were significantly influenced by the triolein/tripalmitin ratio. By increasing the level of triacylglycerol unsaturation the rate of alpha-tocopherol recovery after heating increased significantly from 2.2 to 44.2% whereas in the meantime triacylglycerol polymerization increased from 0 to 3.7%.
Verleyen
T
T
Faculty of Agricultural and Applied Biological Sciences, Department of Organic Chemistry, Gent, Belgium. tom.verleyen@rug.ac.be
Kamal-Eldin
A
A
Dobarganes
C
C
Verhe
R
R
Dewettinck
K
K
Huyghebaert
A
A
D002851:Chromatography, High Pressure Liquid; D004852:Epoxy Compounds / Q000737:chemistry; D006358:Hot Temperature; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry; D011809:Quinones / Q000737:chemistry; D014280:Triglycerides / Q000737:chemistry*; D014304:Triolein / Q000737:chemistry*; D024502:alpha-Tocopherol / Q000737:chemistry*
D004852:Epoxy Compounds; D010545:Peroxides; D011809:Quinones; D014280:Triglycerides; D014304:Triolein; C049375:perhydroxyl radical; C005859:tripalmitin; D024502:alpha-Tocopherol