title: Effects of solubility characteristics of sensitiser and pH on the photooxidation of oil in tuna oil-added acidic O/W emulsions.
abstract: The effects of sensitisers and pH on the oil oxidation of acidic O/W emulsions were studied under light by measuring hydroperoxide content and headspace oxygen consumption in the emulsions. The emulsions consisted of canola and tuna oil (2:1w/w, 32%), diluted acetic acid (64%), egg yolk powder (4%), chlorophyll b or erythrosine (5μM), and/or diazabicyclooctane (DABCO) or sodium azide (0.5M). The emulsion pH values were 2.67, 3.68, and 6.27. Chlorophyll increased oil oxidation in the emulsion under light via singlet oxygen production while erythrosine did not. DABCO significantly decreased photooxidation of the oil containing chlorophyll, suggesting singlet oxygen involvement. However, sodium azide increased photooxidation of the oil containing chlorophyll possibly via azide radical production under acidic conditions. The oil photooxidation was higher in the emulsion containing chlorophyll at pH 6.27 than at pH 2.67 or 3.68, primarily by singlet oxygen and secondarily by free radicals produced from hydroperoxide decomposition.
authors.affiliation: Department of Food and Nutrition, Inha University, Incheon 402-751, Republic of Korea.
authors.forename: Sojin
authors.initials: S
authors.lastname: An
authors.affiliation: Department of Food Science and Technology, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Edwald
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Food and Nutrition, Inha University, Incheon 402-751, Republic of Korea. Electronic address: eochoe@inha.ac.kr.
authors.forename: Eunok
authors.initials: E
authors.lastname: Choe
keywords: Emulsion; Photooxidation; Sensitiser; Singlet oxygen quencher; pH