Simultaneous HPLC-DAD-MS (ESI+) determination of structural and geometrical isomers of carotenoids in mature grapes

Authors

  • Pasquale Crupi,

    1. CRA—Agricultural Research Council—Research Unit for Table Grapes and Wine Growing in Mediterranean Environment, Via Casamassima 148, 70010 Turi (BA), Italy
    Search for more papers by this author
  • Rosa Anna Milella,

    1. CRA—Agricultural Research Council—Research Unit for Table Grapes and Wine Growing in Mediterranean Environment, Via Casamassima 148, 70010 Turi (BA), Italy
    Search for more papers by this author
  • Donato Antonacci

    Corresponding author
    1. CRA—Agricultural Research Council—Research Unit for Table Grapes and Wine Growing in Mediterranean Environment, Via Casamassima 148, 70010 Turi (BA), Italy
    • CRA—Agricultural Research Council—Research Unit for Table Grapes and Wine Growing in Mediterranean Environment, Via Casamassima 148, 70010 Turi (BA), Italy.
    Search for more papers by this author

  • This work was presented at the 1st Mass Spectrometry Food Day 2009, Dec 2nd–3rd 2009, Parma, Italy.

Abstract

Carotenoids are uniquely functional polyene pigments ubiquitous in nature; aside from being responsible for the color of a wide variety of vegetables, interest is being focused on food carotenoids due to their likely health benefits. From analytical point of view, it is important to unequivocally identify individual carotenoid compounds in many food stuffs. Therefore, isolation of standards from natural sources must be encouraged for accurate identifications. Like many fruits, mature grape berries contain numerous carotenoid compounds, mostly found in the skin at levels two to three times higher than in the pulp. Carotenoid compounds in a typical wine grape variety (Negroamaro) grown in Apulian region were investigated by reversed-phase C30 (RP-30) HPLC-DAD-MS (ESI+) analysis. As a consequence of an unusual ionization process of carotenoids, their mass spectra registered in the positive ion mode comprised both protonated molecules and molecular ion radicals with little fragmentation. Additionally, selective collision-induced dissociation (CID) experiments, together with fine structures of the UV–vis spectra, were used to differentiate structural and geometrical isomers. This technique allowed the simultaneous determination of regio- and cis-isomers of lutein (zeaxanthin, 9Z and 9′Z-lutein) and a cis-isomer of β-carotene (9Z- β-carotene), 5,6-epoxy xanthophylls (violaxanthin, (9′Z)-neoxanthin, lutein-5,6-epoxide) and 5,8-epoxy xanthophylls diasteroisomers (neochrome, auroxanthin, luteoxanthin, flavoxanthin, chrysanthemaxanthin). Copyright © 2010 John Wiley & Sons, Ltd.

Ancillary