Turmeric oleoresin is a natural food color used worldwide. Its principal pigment is curcumin, and demethoxycurcumin and bisdemethoxycurcumin are also constituents. In this report, the photo-stability of curcumin reagent, turmeric oleoresin preparations, and a turmeric preparation used as food color was examined and the following results were obtained. 1) Based on the quantity ratios of 3 pigments and the presence of non-coloring constituents, the preparations including a turmeric preparation were divided into 2 categories. 2) It was difficult to detect 3 spots of the pigments by TLC chromatography using a microcrystalline cellulose plate. 3) On photoirradiation, the curcumin reagent was relatively stable in alcohols among various solvents. 4) After the photo-irradiation of curcumin reagent, a cyclisation product of curcumin was detected, as well as decomposed compounds such as vanillic acid. vanillin, and ferulic acid. 5) The photo-stability was not different among the preparations. 6) The photo-decomposed compounds were not detected in any of the preparations.
