title: Evaluation of some carotenoids in grapes by reversed- and normal-phase liquid chromatography: a qualitative analysis.
abstract: Carotenoids in grapes of three Port winemaking cultivars were investigated. Extracts were obtained with n-hexane/diethyl ether mixtures (0/100; 20/80; 50/50; 100/0) and analyzed by normal and reversed phase HPLC-DAD. Selection and identification of peaks were based on spectroscopic characteristics - lambda(max), (%III/II) and k' values, leading to 28 probable carotenoids. Using pure standards, it was possible to identify seven compounds previously described (neochrome, neoxanthin, violaxanthin, flavoxanthin, zeaxanthin, lutein, and beta-carotene), one more type of neochrome reported here, for the first time, and in addition, two geometrical isomers of lutein and beta-carotene were tentatively described. The remaining 17 need to be further identified. High polarity solvent mixtures lead to qualitatively richer chromatograms. Reversed-phase separations allowed the detection of flavoxanthin and the possible geometrical isomer(s) of beta-carotene. Under normal phase, zeaxanthin was detected, and neochromes were better separated from neoxanthin. Extraction with 50/50 n-hexane/diethyl ether mixtures and reversed-phase conditions was the best combination for analysis of the carotenoids, known as precursors of compounds with high aroma impact in wines.
authors.affiliation: Escola Superior de Biotecnologia, Universidade Católica Portuguesa, R. Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal. mendes.pinto@esb.ucp.pt
authors.forename: Maria Manuela
authors.initials: MM
authors.lastname: Mendes-Pinto
authors.forename: A C Silva
authors.initials: AC
authors.lastname: Ferreira
authors.forename: M Beatriz P P
authors.initials: MB
authors.lastname: Oliveira
authors.forename: Paula
authors.initials: P
authors.lastname: Guedes de Pinho
mesh_terms: D002338:Carotenoids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D005638:Fruit / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*; D014920:Wine
chemical_list: D002338:Carotenoids