Enantioselective-GCxGC determination of α-terpinyl ethyl ether in wine: Quantitative analysis and identification of main terpene precursors

The present study investigates the presence of α-terpinyl ethyl ether in wine and gives insights on the chemical processes leading to its formation. The analytical determination of (S)-α-terpinyl ethyl ether and (R)-α-terpinyl ethyl ether enantiomers was obtained by enantioselective comprehensive two-dimensional gas chromatography. Applying the two isomers as variables in combination with closely related terpenes, an accurate classification model of wines for the grape variety was successfully applied to a representative set of single-variety wine samples. Although presenting relatively low absolute concentrations, α-terpinyl ethyl ether (along with α-terpineol) resulted to be an inevitable and irreversible degradation product of linalool. In fact, a conversion study from enantiomerically pure (R)-linalool showed a major loss of the initial chiral configuration, i.e. only a very small enantiomeric excess characterized the product. α-Terpineol itself was also confirmed to be a precursor of α-terpinyl ethyl ether, however this process showed a smaller conversion over two weeks than from linalool, and without losses of the initial chiral configuration. In the real samples, the concentration of α-terpinyl ethyl ether was found to be much lower than that of α-terpineol, regardless of the alcohol-to-water ratio. Finally, olfactory descriptors were qualitatively attributed to each α-terpinyl ethyl ether enantiomer.

Keywords

Wine classification, Enantioselective-GCxGC, Terpene chemistry, Olfactory attributes

Citation

Darnal A, Ceccon A, Magni M, Robatscher P, Poggesi S, Boselli E, Longo E. (2024). Enantioselective-GCxGC determination of α-terpinyl ethyl ether in wine: Quantitative analysis and identification of main terpene precursors. Applied Food Research. 4. 2.

URI

https://mro.massey.ac.nz/handle/10179/71972

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