Characterization of chemical compounds susceptible to be extracted from cork by the wine using GC-MS and 1H NMR metabolomic approaches.

This work presents a metabolomics study of cork by gas chromatography-mass spectrometry (GC-MS) and 1H nuclear magnetic resonance (NMR) spectroscopy to characterize compounds susceptible to be extracted from cork by the wine in an attempt to find a relationship between the content of these compounds and the geographical origin of cork. Cork from eleven geographical regions was studied, five from Portugal and six from Spain. Unsupervised pattern recognition techniques unveiled three main clusters of regions according to their chemical similarity but not related with geographical proximity. Nineteen compounds were found to be responsible for the clusters, including terpenes (trans-squalene, friedelin, camphene, trans-3-pinanone, 1-terpinen-4-ol, two sesquiterpenes), polyphenols (vescalagin, castalagin), among others (pyrogallol, glucosan, sitost-4-en-3-one, o-cymene, quinic acid, five unknowns). These preliminary results unveiled the potential for a more efficient selection of cork planks for stoppers production based on the compounds susceptible to be extracted from cork by the wine.

Assessment of oxidation compounds in oaked Chardonnay wines: A GC-MS and 1H NMR metabolomics approach.

The oxidation of oaked Chardonnay wine during long-term storage was studied by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC/MS) and proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Three distinct groups of wine were defined based on the browning index: control, least oxidized (OX1) and most oxidized (OX2). HS-SPME-GC/MS and 1H NMR spectroscopy enabled the profiling of a total of 155 compounds in all wine samples including aldehydes, ketones, esters, polyphenols, among other classes. Acetaldehyde, 3-methylbutanal, 2-phenylacetaldehyde, methional, 3-penten-2-one, ß-damascenone and four unknown carbonyl compounds showed the highest percentage of variation with oxidation. Novel oxidation markers found in this work include pentanal, 3-methyl-2-butanone, 3-penten-2-one, 2-methyltetrahydrofuran-3-one, ß-damascenone, ethyl 2-methylbutanoate and vinyl decanoate. In addition, several correlations between polyphenols, aroma compounds and absorbance at 420 nm (A420) were observed, suggesting the occurrence of chemical reactions with a possible impact in wine browning.

Reactivity of Cork Extracts with (+)-Catechin and Malvidin-3-O-glucoside in Wine Model Solutions: Identification of a New Family of Ellagitannin-Derived Compounds (Corklins).

The aim of this study was to evaluate the reactivity of phenolic compounds extracted from cork stoppers to wine model solutions with two major wine components, namely, (+)-catechin and malvidin-3-O-glucoside. Besides the formation of some compounds already described in the literature, these reactions also yielded a new family of ellagitannin-derived compounds, named herein as corklins. This new family of compounds that were found to result from the interaction between ellagitannins in alcoholic solutions and (+)-catechin were structurally characterized by mass spectroscopy, nuclear magnetic resonance, and computational methods.