Evaluation of Some Carotenoids in Grapes by Reversed- and Normal-Phase Liquid Chromatography: A Qualitative Analysis

• Published in: Journal of agricultural and food chemistry 2004-05, Vol.52 (10), p.3182-3188
• Main Authors: Mendes-Pinto, Maria Manuela, Ferreira, A. C. Silva, Oliveira, M. Beatriz P. P, Guedes de Pinho, Paula
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; carotenoids; Carotenoids - analysis; Chromatography, High Pressure Liquid; Drug Stability; Fermented food industries; Food industries; Fruit - chemistry; Fruit and vegetable industries; fruit composition; Fundamental and applied biological sciences. Psychology; high performance liquid chromatography; Port wine cultivars; reversed-phase high performance liquid chromatography; Vitis - chemistry; Wine; wine cultivars; wine grapes; Wines and vinegars
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0499469

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 − λmax, (%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 β-carotene), one more type of neochrome reported here, for the first time, and in addition, two geometrical isomers of lutein and β-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 β-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. Keywords: Port wine grapes; carotenoid identification