Influence of Interannual Meteorological Variability on Yeast Content and Composition in Sangiovese Grapes

Abstract

Kloeckera apiculata and Candida zemplinina represent almost the totality of non-Saccharomyces yeasts in grape and fresh musts. These yeasts can accumulate secondary metabolites that are commonly known to increase the aromatic complexity of wine; thus, variations in their total number and ratio may lead to changes in wine taste and flavor. These variations are determined by numerous variables, including climate conditions and viticultural practices that can affect the environment of the yeasts and, in turn, their quantity and composition. This may consequently give rise to changes in the final sensory characteristics of a wine. This work assessed the long-term relationship (1997–2012) between yeast quantity and composition and the main meteorological variables (air temperature, relative humidity, and rainfall) in a Sangiovese vineyard located at the Brunello di Montalcino Wine Consortium (Tuscany). Results indicated that weather conditions 25 to 30 days before harvesting were correlated with total yeasts, particularly rainfall and relative humidity (r ~0.8). Moreover, K. apiculata and C. zemplinina were found to be correlated with temperature 10 days before grape harvest at the same time as stripping practice (r = −0.66 and r = 0.52, respectively). These results suggest that both climate and management may affect microbial community and its composition. This aspect will be fundamental for spontaneous fermentation and for maintaining the high quality of the wines in the coming decades.