Kinetic Model for Studying the Isomerization of α- and β-Carotene during Heating and Illumination

Article abstract of DOI:10.1021/jf00047a006

The thermoisomerization and iodine-catalyzed photoisomerization of all-trans-α- and all-trans-β-carotene were kinetically studied using regression models. Carotene samples were heated at varied temperatures or exposed to a 20 W light for varied lengths of time. Isomerization and degradation reactions were monitored using HPLC with diode array detection. Four cis isomers of β-carotene and three cis isomers of α-carotene were separated and detected. The degradations of both carotenes under heating at 150 deg C or iodine/light treatment may fit the reversible first- order model. 9-cis and 13-cis were the major β-carotene isomers formed during heating, while 13,15-di-cis was favored during iodine-catalyzed photoisomerization. The formation of 9-cis and 13-cis form all-trans-α-carotene was dependent upon the extent of heat or iodine/light treatment, and the latter was formed in greater amount under either treatment. Keywords: α-Carotene; β-carotene; thermoisomerization; photoisomerization; kinetic study