title: Identification of isolutein (lutein epoxide) as cis-antheraxanthin in orange juice.
abstract: The carotenoid profile of orange juice is very complex, a common characteristic for citrus products in general. This fact, along with the inherent acidity of the product, which promotes the isomerization of some carotenoids, makes the correct identification of some of these pigments quite difficult. Thus, one of the carotenoids occurring in orange juice has been traditionally identified as isolutein, a term used to refer to lutein epoxide, although enough evidence to support that identification has not been given. In this study, the carotenoid previously identified as isolutein/lutein epoxide in orange juice has been isolated and identified as a 9 or 9'-cis isomer of antheraxanthin as a result of different tests. To support this identification, a mixture of geometrical isomers of lutein epoxide isolated from petals of dandelions was analyzed under the same conditions used for orange juice carotenoids to check that neither their retention times nor their spectroscopic features matched with those of the orange juice carotenoid now identified as a cis isomer of antheraxanthin.
authors.affiliation: Laboratory of Food Color & Quality, Departament of Nutrition and Food Science, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Meléndez-Martínez
authors.forename: George
authors.initials: G
authors.lastname: Britton
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Vicario
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Heredia
mesh_terms: D001628:Beverages / Q000032:analysis*; D002855:Chromatography, Thin Layer; D032084:Citrus sinensis / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis*; D005638:Fruit / Q000737:chemistry*; D013237:Stereoisomerism; D024341:Xanthophylls / Q000032:analysis* / Q000737:chemistry
chemical_list: D005419:Flavonoids; D024341:Xanthophylls; C031140:antheraxanthin; C059811:orobol