Analysis of the effect of grape withering on aroma profile of wine using HS-SPME and GCxGC TOF-MS

Drying of grapes and subsequent wine-making are processes that characterize some premium quality Italian wines including in particular Amarone, a “Passito” dry red wine produced by a traditional, slow drying grape process. During this process, depending on the occurrence of favourable seasonal conditions for a noble rot infection, a positive impact on volatile compounds can develop[1-2]. In recent years a more modern drying approach has been suggested, with the aim of faster and more strictly controlled drying of grape. The drying conditions are expected to lead to different wine composition and the aim of this study was to evaluate the differences in wine volatile compounds produced from a) traditional and b) modern processes applying 2 different analytical approaches, SPME followed by GCxGC TOF MS and a classical approach with SPE followed by GC MS [3]. The wines produced from two different grapevine cultivars, Sangiovese and Corvina, with two different grape drying systems (slow vs. accelerated) were analyzed. The profiles of volatile compounds in wines were, as expected, quite different and the sample were clearly separated by PCA. The compounds that characterize the wines obtained by traditional drying system were well distinguishable and some of them were produced by Botrytis cinerea such as 1-octen-3-ol, p- cymene, 4-terpineol, benzaldehyde, phenylacetaldeide. The concentrations of fatty acids and ethyl esters were higher in the wine produced by faster drying system as already reported in the literature [2], as well as the 3- hydroxy ethyl butyrate, phenyl ethyl acetate and linalool. The preliminary results of this survey calls for further metabolomic and transcriptomic analyses of grapes, in order to better understand how the variability of the grape metabolism induced by different drying conditions can influence the aroma of Amarone wines