Effects of fatty acid composition and β-carotene on the chlorophyll photosensitized oxidation of W/O emulsion affected by phosphatidylcholine.

Chlorophyll photosensitized oxidation of W/O emulsion consisting of oils with different fatty acid composition was studied and β-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 β-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 β-carotene to the emulsion significantly decreased the oil oxidation under chlorophyll photosensitization, however, co-addition of phosphatidylcholine decreased the antioxidant activity of β-carotene, suggesting an antagonistic antioxidation between them. 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 β-carotene with phosphatidylcholine as emulsifier.