Ozone Fading of Organic Colorants: Products and Mechanism of the Reaction of Ozone with Curcumin

The organic colorant curcumin [177-bis(4-hydroxy-3- methoxyphenyl)-l,6-heptadiene-3,bdionew]a s exposed to ozone in purified air in the dark, and the exposed samples were analyzed by mass spectrometry. The major reaction products included vanillin (4-hydroxy-3-methoxybenzaldehyde) and vanillic acid (4-hydroxy-3-methoxybenzoic acid). These products and the corresponding loss of chromophore (i.e., fading of curcumin) are consistent with a reaction mechanism involving electrophilic addition of ozone onto the olefinic bonds of curcumin. Vanillin and vanillic acid did not react with ozone under the conditions of this study