Bueno Mónica, Zapata Julián, Ferreira Vicente
Laboratory for Flavor Analysis and Enology, Aragón Institute of Engineering Research (I3A), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain.
Laboratory for Flavor Analysis and Enology, Aragón Institute of Engineering Research (I3A), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain.
J Chromatogr A. 2014 Nov 21;1369:33-42. doi: 10.1016/j.chroma.2014.10.004. Epub 2014 Oct 13.
This paper presents a new strategy for the direct evaluation of odor-active carbonyls in the wine headspace and for the simultaneous estimation of their amounts in odorless bonded forms. In the final developed strategy, 25 mL of wine are spiked with internal and surrogate standards and let to equilibrate for at least 12 h in an oxygen-free chamber. Ten milliliter of the sample are then transferred to a standard headspace vial. Carbonyls in the headspace are preconcentrated on a PDMS/DVD fiber keeping the sample unstirred at 45°C for just 10 min and are further analyzed on a GC-MS equipped with a quadrupole in SIM mode. Normalized peak analyte areas interpolated in calibration plots built with synthetic wines give estimations of the concentrations of free forms, while the ratios of the areas of surrogates observed in wines to those observed in synthetic wine make it possible to get estimations of the proportion of each analyte present in bonded non-volatile form. The validity of this approach has been demonstrated both via standard recovery experiments and via the analysis of samples previously incubated with glyoxal in order to break aldehyde-bisulfite complexes. In general, method detection limits (below 1 μg L(-1)), precision (RSD (%)<10%) and accuracy are satisfactory for 12 studied carbonyls. Results demonstrate that wine contain relevant amounts of aldehydes (more than 95% in some cases) in the form of reversible odorless complexes, supporting a previous observation about the potential implication of these complexes on the development of oxidized aroma.
本文提出了一种直接评估葡萄酒顶空中气味活性羰基化合物以及同时估算其无气味结合形式含量的新策略。在最终确定的策略中，向25 mL葡萄酒中加入内标和替代标准物，并在无氧室内平衡至少12小时。然后将10 mL样品转移至标准顶空瓶中。顶空中的羰基化合物在PDMS/DVD纤维上进行预浓缩，样品在45°C下保持静止仅10分钟，然后在配备四极杆的GC-MS上以SIM模式进行进一步分析。在校准图中通过合成葡萄酒构建的归一化峰分析物面积可估算游离形式的浓度，而葡萄酒中观察到的替代物面积与合成葡萄酒中观察到的替代物面积之比则可估算每种分析物以结合非挥发性形式存在的比例。通过标准回收率实验以及对先前与乙二醛孵育以破坏醛-亚硫酸氢盐络合物的样品进行分析，均证明了该方法的有效性。总体而言，对于12种研究的羰基化合物，方法的检测限（低于1 μg L(-1)）、精密度（RSD (%)<10%）和准确度均令人满意。结果表明，葡萄酒中含有相当数量的醛（某些情况下超过95%）以可逆无气味络合物的形式存在，支持了先前关于这些络合物对氧化香气发展潜在影响的观察结果。
