AEROBIC PHOTOOXIDATION OF THE ROSE-HIP (R OSE AFF RUBIGINOSA L) OIL -KINETICS AND MECHANICS

A kinetic and mechanistic study on the sensitized photooxidation of Ro se Hip (wild Rose) oil was carried out. The oil is widely employed as a commercial skin moisturizer. Both, the unsaturated fatty acids of th e crude oil and their methyl esters, are effectively photoxidized when irradiated with visible light in a mechanism involving singlet molecu lar oxygen. The photooxidation occurs both, in the presence and in the absence of specific singlet oxygen sensitizers. In the latter case th e antocyanins, natural components of the oil and responsible for the r ed-yellowish coloration operate as photosensitizers. The bimolecular r ate constants for the photooxidation of the fatty acids and their meth yl esters, are in the range of 1-3 x 10(5) M-1 s-1. The remarkable pho tooxidative inestability of the Rosa mosqueta oil, suggest specials co nditions of handling and storage in order to prevent day light expossu re.