Panelists performed blind quantitative descriptive analysis using a standard list of descriptors including six odor (overall oaky, fruity, sawdust, vanilla, toasty, spicy) and five taste descriptors (acidity, bitterness, tannic intensity, structure, length). The sensory sessions were organized by series with the same wine aged in fire-bent and immersion/fire-bent barrels. The order of presentation was arbitrary and different for different panelists to obtain more objective data.
The tasting sessions were conducted in tasting rooms following the usual practices in wine tasting and were conducted by a session observer. Before the sensory analysis, the bottle was tasted in order to look for possible off-flavors and was rejected if there was an abnormal odor.
Panel members awarded 0 to 10 points according to the intensity of each descriptor (0 – very weak, 10 – very strong).
The values given by each taster were normalized using the average value for that taster over the entire series. The Independent Student’s T-test was applied to the normalized values to identify the descriptors for which there was a variation in intensity between the barrels made using “immersion” and the “traditional process.”
Only those descriptors showing differences with a probability below 5% were retained for further processing.
Analysis of volatile compounds
The following 19 odoriferous volatile molecules from oak wood were assayed in the wines using GC-MS:3
• furan and pyran compounds (furfural, 5-hydroxymethyl-furfural, 5-methyl-furfural, furfuryl alcohol, maltol, and ethyl maltol) – class of compounds characterized by toasty and butterscotch odors in pure state;
• aromatic aldehydes (vanillin and syringaldehyde) – class of compounds characterized by vanilla/woody odors in pure state;
• volatile phenols (guaiacol, 4-methyl-guaiacol, eugenol, isoeugenol, o-cresol, m-cresol, phenol, syringol, and allylsyringol) – class of compounds characterized by smoky, phenol and spicy odors in pure state;