| Abstract
| - Carotenoids, lutein and zeaxanthin, found in fruits and vegetables, comprise the macula pigment ofthe eye. These carotenoids exist in plants as the all-trans geometric form; however, in human plasma,cis isomers of these carotenoids have also been identified. Thermal processing can induce carotenoidtrans to cis isomerization. The aim of this research was to determine if thermal processing inducesisomerization of lutein and zeaxanthin and to quantify the extent of this reaction. High-performanceliquid chromatography was used to separate and quantitate geometric isomers of lutein and zeaxanthin.Isomers were tentatively identified by UV−visible absorbance spectra, comparison of retention timesto those of isomerized standards using C30 chromatography, and mass spectrometry. Thermalprocessing increased the percent cis isomers of lutein and zeaxanthin up to 22 and 17%, respectively.Further studies are needed to consider the physiological impact of consuming carotenoid isomers inprocessed vegetables. Keywords: C30 reversed-phase; HPLC; lutein; zeaxanthin; geometrical isomers
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