ABSTRACT
UNLABELLED: Chlorophyll photosensitized oxidation of W/O emulsion consisting of oils with different fatty acid composition was studied and ß-carotene effects on the singlet oxygen oxidation affected by phosphatidylcholine were evaluated by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. An emulsion was composed of purified oil (sunflower, soybean, canola, or olive oil), water, and xanthan gum (50:50:0.35, w/w/w) with addition of phosphatidylcholine (0 or 250 ppm) and ß-carotene (0, 1, 5, or 10 ppm). PV and CDA content of oil in the emulsion were increased with time under chlorophyll photosensitized oxidation, and the oxidation rate was higher in the emulsion consisting of sunflower or soybean oil whose polyunsaturated fatty acids content was high compared to canola or olive oil. Addition of ß-carotene to the emulsion significantly decreased the oil oxidation under chlorophyll photosensitization, however, co-addition of phosphatidylcholine decreased the antioxidant activity of ß-carotene, suggesting an antagonistic antioxidation between them. PRACTICAL APPLICATION: The results of this study can be applied to the area of emulsion foods such as salad dressing to have improved texture and stability by decreasing the oil oxidation and providing desirable color by use of ß-carotene with phosphatidylcholine as emulsifier.
Subject(s)
Chlorophyll/metabolism , Fatty Acids/analysis , Phosphatidylcholines/metabolism , Photosynthesis/drug effects , beta Carotene/analysis , Antioxidants/metabolism , Color , Emulsifying Agents/metabolism , Fatty Acids/metabolism , Fatty Acids, Monounsaturated/analysis , Fatty Acids, Monounsaturated/metabolism , Fatty Acids, Unsaturated/analysis , Linear Models , Olive Oil , Oxidation-Reduction , Plant Oils/analysis , Plant Oils/metabolism , Rapeseed Oil , Singlet Oxygen/metabolism , Soybean Oil/analysis , Soybean Oil/metabolism , Sunflower Oil , beta Carotene/metabolismABSTRACT
Interaction of phosphatidylcholine (PC) and α-tocopherol (α-Toc) on the oxidation of oil in the emulsion consisting of sunflower oil and water under singlet oxygen at 25 °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 α-Toc decreased the values of peroxides and CDAs of oil in the emulsion via singlet oxygen quenching. PC and α-Toc showed simply additive interaction in decreasing the singlet oxygen oxidation of oil in the emulsion. α-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 α-Toc was not. α-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.
