Extending the Influence of Terroir through the Spontaneous Fermentation of Pinot Noir in the Vineyard: A Case Study of Greystone Vineyard Fermentation

This study investigates the influence of vintage and fermentation environment on the microbial diversity, chemical composition, and volatile profiles of Pinot Noir wines, with a focus on comparing vineyard (outdoor) and winery (indoor) fermentations across two consecutive vintages, 2019 and 2020. Grapes were hand-harvested from a single vineyard and subjected to spontaneous fermentations in three tanks for each fermentation environment. Nonmetric multidimensional scaling (NMDS) and PERMANOVA analyses revealed significant differences in fungal community composition between fermentation environments and vintages. Vineyard fermentations consistently exhibited higher levels of non-<i>Saccharomyces</i> yeasts during fermentation, which contributed to increased production of microbial-derived esters, such as hexyl acetate and isobutyl acetate. Winery fermentations, in contrast, showed higher concentrations of anthocyanins, contributing to enhanced color intensity and stability. Vintage effects were more evident than fermentation environment, with the 2019 vintage favoring higher concentrations of phenolics, anthocyanins, higher alcohols (e.g. isoamyl alcohol), and volatile phenols (e.g. guaiacol and eugenol), while the 2020 vintage enhanced the retention of esters and floral terpenes (e.g. linalool). These findings highlight the distinct wine styles achievable through vineyard and winery fermentations, as well as the interplay between climatic conditions and fermentation environment. This work provides novel insights into the potential of vineyard fermentations for expressing microbial terroir and offers practical strategies for optimizing wine production under varying climatic and site-specific conditions.