Agricultural Research Council-Research Unit for Table Grapes and Wine Growing in Mediterranean Environment, Via Casamassima 148, 70010 Turi (BA), Italy.
J Mass Spectrom. 2010 Sep;45(9):971-80. doi: 10.1002/jms.1794.
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 C(30) (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).
类胡萝卜素是一种独特的功能多烯色素，广泛存在于自然界中；除了赋予各种蔬菜颜色外，由于其可能对健康有益，人们对食物类胡萝卜素的兴趣也越来越大。从分析的角度来看，明确鉴定各种食品中的单个类胡萝卜素化合物非常重要。因此，必须鼓励从天然来源中分离标准品，以进行准确的鉴定。与许多水果一样，成熟的葡萄浆果含有许多类胡萝卜素化合物，主要存在于果皮中，其含量是果肉的两到三倍。采用反相 C(30)（RP-30）HPLC-DAD-MS（ESI(+))分析方法研究了在普利亚地区种植的典型酿酒葡萄品种（Negroamaro）中类胡萝卜素化合物。由于类胡萝卜素的一种异常电离过程，它们在正离子模式下记录的质谱图既包括质子化分子，也包括分子离子自由基，几乎没有碎片化。此外，还使用选择性碰撞诱导解离（CID）实验以及 UV-vis 光谱的精细结构来区分结构和几何异构体。该技术允许同时测定叶黄素（玉米黄质、9Z 和 9'Z-叶黄素）和β-胡萝卜素（9Z-β-胡萝卜素）的顺式异构体、5,6-环氧叶黄素（violaxanthin、(9'Z)-新黄质、叶黄素-5,6-环氧化物）和 5,8-环氧叶黄素非对映异构体（neochrome、auroxanthin、luteoxanthin、flavoxanthin、chrysanthemaxanthin）的区域和顺式异构体。
