VOLATILE COMPOUNDS AND SENSORY PROFILE OF NEBBIOLO RED WINES TREATED WITH WOOD FORMATS ALTERNATIVE TO BARRELS

Abstract

In winemaking, the use of wood products alternative to barrels, has become a useful tool for the achievement of numerous oenological objectives, including the fast release of desirable volatile and polypheno- lic compounds, colour stabilization, and important economic advantages if compared to the traditional barrel production. Among a huge array of variables, the wood format, the vinification protocol, especially the moment of the infusion of the woods and the exposed surface area of the alternative woods are of relevant significance, since they may influence the speed and intensity of the aroma transfer from the wood to the wine defining different sensory profiles.

The oak wood formats used during this research study were sticks, cubes, and chips, added in commercial doses to red Nebbiolo wines, in two different stages of the vinification process: during and after the alcoholic fermentation. Samples were analyzed for their aromatic composition at the racking and after seven months of aging. The sample preparation was carried out by Solid Phase Extraction (SPE) using polymeric cartridges with high load capacity and multiple retention mechanisms. Extracts were analyzed by gas chromatography–mass spectrometry (GC–MS) and gas chromatography-flame ionization detector (GC FID). The sensory profiles of the wines were assessed after seven months by a trained panel.

The quantitative and qualitative profile of oak aromas resulted strongly dependent on both the moment of application and the type of wood. Statistically higher values of vanillin and furan compounds were noted both in the wines where wood was added after the fermentation and in the wines treated with sticks. Wines treated with cubes showed elevated values of benzoic aldehydes and wines with chips statistically higher levels of whisky lactone, a key molecule for the expression of the boisée note in wines.

Sensory analysis results confirmed a significative greater intensity of descriptors such as, vanilla, or oak wood related to boisée notes, in the wines treated with cubes and chips, well recognizable if compared to those with sticks which had significantly higher violet highlights. Furthermore, the use of cubes accentuated the perception of some spicy scents such as cloves and pepper. In summary, considering the overall results, oak cubes appear to impart intermediate characteristics if compared to sticks and chips, conferring in wines a more balanced aroma and sensory profile.