Molecular characterization of toasted oak wood (Quercus petraea) volatilome by untargeted GCxGC-ToFMS analysis

Application of heat to oak wood to make barrels or alternatives produces many volatile compounds involved in the formation of specific nuances found in wines and spirits. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-ToFMS) was used to characterize the volatilome of oak wood toasted at increasing intensities (until 220°C). Using automatic deconvolution, 525 volatile reproducible compounds were detected, whereas 85 volatile markers of toasting were identified. Some of them develop an odor and are linked with the intensity of toasting and overall sensory balance (green vs. roasted/spicy). Others are reported for the first time in oak wood such as 2-methyl-benzofuran, with a toasted odor, and 2-hydroxy-2-cyclopenten-1-one and 3-methyl-1,2-cyclohexanedione with a caramel odor. Quantification by GC-ToFMS validated these results. Their olfactory detection thresholds were 45.7 μg/L for, 158 μg/L and 13.5 μg/L, respectively, suggesting a sensory impact on wine aroma