Comparison between the volatile chemical profile of two different blends for PDO “Valpolicella Superiore”

Abstract

Valpolicella is a famous wine producing region located in the north of Verona close to Garda lake and owes its fame above all to the production of two Protected Designation of Origins (PDOs) withered wines: Amarone and Recioto. Nowadays the production of another PDO, Valpolicella Superiore is gaining more attention by the consumers, increasing the interest of the wineries to improve the quality of this wines. All the Valpolicella wines are produced with a unique grape blend, mainly Corvina, Corvinone, Rondinella and a range of other minor varieties.Traditionally, Valpolicella product regulation required the blend to have a greater proportion (equal to …) of Corvina grape, from 2019 it changed allowing new blend compositions. For this reason, studying the volatile chemical profiles of different Valpolicella blends to support wine makers in the choices of the winery represents a field of great interest.The study aimed to evaluate the volatile chemical and sensory composition of two different blends, one “traditional” (70% Corvina, 30% Rondinella) and one “experimental” (60% Corvinone, 20% Corvina, 20% Rondinella).The grapes were supplied by six wineries in Valpolicella, four of which provided both blends, whereas for two companies were produced only traditional wines. Winemaking was performed under standardized conditions. Free volatile compounds as well as glycosidic precursors were analysed with gas chromatography mass spectrometry (GC-MS) techniques coupled with SPE and SPME extractions. Fermentation kinetics were found to be influenced by the different composition of the blends.We found many significant difference in volatile chemical composition among the two blends. This study found that Corvina-based wines have a higher concentration of terpenoids than Corvinone-based wine, conversely experimental blend wines, showed  a higher concentration of norisoprenoids. Interestingly multivariate analysis of the volatile compounds showed higher influence of the terroir compared to blend influence. This was reasonable because 40% of the grapes in the blends are the same and the remaining 60% varies. Moreover this result gives indications about the importance of the origin of the grapes and of the terroir of Valpolicella.