Oxidation of beta-carotene with sin

Oxidation of beta-carotene with singlet oxygen was also found
FACTORS INFLUENCING THE CHEMICAL STABILITY OF CAROTENOIDS IN FOODS 523
to produce beta-apo-14′-carotenal, beta-apo-10′-carotenal, betaapo-
8′-carotenal, beta-ionone, and beta-carotene 5,8-endoperoxide
as determined by HPLC, GC-MS, and LCMS/MS
(Stratton et al., 1993). Chemical oxidation products were also
found to form during the irradiation of lycopene in the presence
of oxygen and methylene blue (sensitizer). These products
were determined to be apo-6′-lycopenal, and a mixture of
seven short-chain oxygenated compounds including 2-methyl-
2-hepten-6-one usingMS, UV, IR, and 1H- and 13C-NMR spectra.
The formation of these products led to the hypothesis that
singlet oxygen, formed in the presence of the methylene blue
sensitizer, reacted with lycopene to form a cyclic peroxide at
C5-C6. Being a relatively unstable compound, this cyclic peroxide
could easily undergo scission to form the detected products