Interaction of Phosphatidylcholine and α-Tocopherol on the Oxidation of Sunflower Oil and Content Changes of Phosphatidylcholine and Tocopherol in the Emulsion under Singlet Oxygen

Interaction of phosphatidylcholine (PC) and alpha-tocopherol (alpha-Toc) on the oxidation of oil in the emulsion consisting of sunflower oil and water under singlet oxygen at 25 degrees C was studied by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. Singlet oxygen was produced by chlorophyll b under 1700 lux. Single addition of PC or alpha-Toc decreased the values of peroxides and CDAs of oil in the emulsion via singlet oxygen quenching. PC and alpha-Toc showed simply additive interaction in decreasing the singlet oxygen oxidation of oil in the emulsion. alpha-Toc was a physical quencher of singlet oxygen in the emulsion, but PC involved chemical quenching in the antioxidant action. Chlorophyll and PC contents were decreased in the emulsion under singlet oxygen, while alpha-Toc was not. alpha-Toc protected chlorophyll and PC from degradation, and was a more important component than PC in the oil oxidation under singlet oxygen in the emulsion.