further information about the reaction occurring in this system was
gathered by adding AIBN (2,2′-azo-bis-isobutyronitrile (a free
radical reaction initiator), BHT (butylated hydroxytoluene), or
alpha-tocopherol to the system. Both BHT and alpha-tocopherol
reduced the rate of oxidation product formation, while AIBN
increased the rate of product formation. These results indicate
that beta-carotene oxidation involves free radicals. The authors
of this study propose that autoxidation may perhaps begin as
beta-carotene in solution forms isomers via a biradical process
(this may occur easily in solvent at 30◦C), as seen in Fig.
4. The twisting of the molecule during the isomerization process
may lead to an unpaired spin state, which can react easily
with oxygen to form a carbon-peroxyl triplet biradicals. These
may go on to form endo-peroxides or to react with a neutral
beta-carotene molecule, forming an epoxide and a carotene
alkoxyl radical. From the compounds detected in this study,
it was concluded that the autoxidation process results first in the
production of epoxides, carbonyl compounds, and an uncharacterized
oligomers, followed by further oxidation reactions of
these compounds to produce secondary short chain carbonyl
compounds, carbon dioxide, and carboxylic acids