Studies in photooxidation of olive oil

Abstract

Abstract Photooxidation of olive oil, bleached to remove most non‐triglyceride components, was studied to elucidate the role of added chlorophyll a, pheophytin a and b, α‐ and β ‐carotene, d‐ α ‐tocopherol and nickel dibutyldithiocarbamate. Chlorophyll functioned as a photosensitizer resulting in rapid oxidation of the oil and the added components and loss of color. α ‐ and β ‐carotene acted essentially equally as singlet oxygen quenchers. α ‐tocopherol had little apparent effect on the oxidation rate. Carotenes and tocopherols apparently were destroyed more rapidly when chlorophyll was present. The ratio of peroxide value to conjugated dienoic acids formed developed greater values when chlorophyll was present, thus suggesting a singlet oxygen effect in the system. Pheophytin also proved to be an oxidation promoter.