Influence of grapes origin and yeast strain on aroma profile of corvina and corvinone dry passito wines

Abstract

AIM: Valpolicella is a wine region characterized by a wide use of the technology of grape drying for the production of two red passito wines, recognized as PDOs, “Recioto della Valpolicella” and the most famous “Amarone della Valpolicella”. Geographical origin of the grapes can influence wine composition by grape chemical composition yeast behaviour during fermentation. This study investigates the impact of different commercial yeast strains on aroma profiles of wines produced with withered grapes of different origins. In addition, the influence of spontaneous fermentation is also considered.

METHODS: Experimental red wines were produced with a standard winemaking protocol with withered Corvina and Corvinone grapes obtained from two different geographical areas within the Valpolicella region. Fermentations were carried out with four different commercial yeasts plus a spontaneous fermentation. Wines were analysed by means of SPE- and SPME-GC-MS techniques and sensory analysis (sorting task).

RESULTS: Data analysis of volatile chemical compounds showed significative difference for several compounds both for yeast strain and grape origins, with the latter playing a major role. Differentiation attributable to grape origin was related to different contents of terpenes, norisoprenoids, benzenoids and C6 alcohols. Differences due to yeast strains were mostly associated with esters, alcohols and acids. Certain compounds primarily associated with grape, like geraniol, 3-hydroxy-β-damascone and vanillin, were also affected by yeast strain. Spontaneous fermentations were characterized by higher levels of ethyl acetate and acetic acid, above the detection threshold. In agreement with chemical data, sorting tasks indicated that grape area of origin played a major role. In both varieties, spontaneous fermentations resulted in a single sensory cluster, regardless of grape geographical origins.

CONCLUSIONS:

Most volatile compounds were primarily affected by grape composition, while the contribution of yeast was lower. Sensory analysis also confirmed this observation, since grape origin had a greater influence than employed yeast. Concerning spontaneous fermentations, we found increased content of unpleasant compounds and a loss of sensory diversity associated with grape origin. These results highlight the primary importance of grape composition to the expression of aroma attributes related to geographical origin.

ACKNOWLEDGMENTS:

Azienda Agricola f.lli Tedeschi is acknowledged for financial support