A ternary system of α-tocopherol with phosphatidylethanolamine and l-ascorbyl palmitate in bulk oils provides antioxidant synergy through stabilization and regeneration of α-tocopherol

The stabilization of fats and oils against oxidative lipid deterioration is still a great challenge. The synergistic interaction between phospholipids, l-ascorbate, and tocopherols have not yet been comprehensively understood. The mechanism of the synergistic antioxidant effect of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (PE) in mixtures with l-ascorbyl palmitate (AP) and α-tocopherol (α-Toc) was investigated in an ethyl linoleate model and sunflower oil at 110 °C. The mixture of PE, AP, and α-Toc is stabilized through continuous regeneration of α-Toc from its oxidation product α-tocopherylquinone (α-TQ). This reaction is catalyzed by acids and proceeded through the formation of the α-tocopherone ion (T+) as an intermediate product. In addition to the direct reduction of T+ by AP, PE can also cause regeneration indirectly by reacting with dehydroascorbyl palmitate (DHAP) or other tricarbonyl compounds to form amino reductones. PE and AP undergo an amino-carbonyl reaction to form the condensate PE(AP)2.