title: Thermal Isomerization of All-trans-Lutein in a Benzene Solution.
abstract: Four major cis-lutein isomers could be identified after thermal isomerization of all-trans-lutein in a benzene solution system; namely, 13'-, 13-, 9'- and 9-cis-luteins. Using both all-trans-lutein and a mixture of these purified cis-luteins as starting materials, the quantitative changes determined by HPLC response show that this thermal isomerization was a reversible reaction. The equilibrium constants (k C ) of 13'- and 13-cis-luteins were higher than those of 9'-, and 9-cis-luteins, suggesting that the amount formed of the former isomers was higher than that of the latter.
authors.affiliation: a Laboratory of Food Chemistry, College of Agriculture, Osaka Prefecture University.
authors.forename: A
authors.initials: A
authors.lastname: Subagio
authors.affiliation: a Laboratory of Food Chemistry, College of Agriculture, Osaka Prefecture University.
authors.forename: N
authors.initials: N
authors.lastname: Morita
authors.affiliation: b Faculty of Science and Technology, Kinki University.
authors.forename: S
authors.initials: S
authors.lastname: Sawada
keywords: carotenoid; isomerization; lutein