Varietal and pre-fermentative volatiles during ripening of Vitis vinifera cv Nebbiolo berries from three growing areas.

Flavour analysis of grape is a key step in quality evaluation. The Stir Bar Sorptive Extraction technique (SBSE, 'Twister'®) was used to assess varietal and pre-fermentative volatile accumulation in 'Nebbiolo' berries, from véraison to harvest. Grapes were collected in three vineyards, representing different 'crus' in the cultivation areas of Barolo, Barbaresco and Roero (North-West Italy). Volatile constituents of grapes were identified and quantified by GC-MS. We demonstrate the influence exerted by the growing location on volatile concentration and profile, as well as on the timing of volatile accumulation. The accumulation of certain classes of compounds, considered favourable for defining berry quality, followed common patterns, and was negatively correlated to that of compounds with herbaceous and grassy notes, such as the C6 compounds. PCA analysis shows that the concentrations of varietal and pre-fermentative volatiles were more effective in separating growing areas than dates of harvest. Grapes from the Barbaresco area, showing higher values of the concentration ratio between favourable and unfavourable compounds throughout ripening, could be statistically separated from grapes from the other areas.