Glycine Zhujun Jiang* and Patrick A. Gibney
*Cornell University, 411 Tower Road, Room 357, Ithaca, NY, 14853 (zj43@cornell.edu)

Terroir is the relationship between the characteristics of a wine and its geographic origin. Early research into terroir focused on geographic differences in climate, soil, and human practices. A growing understanding of wine-associated microorganisms has led to more studies focused on the microbial contribution to terroir. Investigations into the role of microbial terroir have used modern sequencing technologies to determine that microbial populations from different geographic areas contain different microbes. While these studies consider microbial population variations as evidence for microbial terroir, the quantitative effects of these different microbial populations on wine chemistry, aroma, or flavor are typically not measured. The goal of this study was to quantitatively evaluate the role of microbial terroir in wine, including its effects on wine chemistry and sensory perception. Over two years, grapes were sampled
immediately before harvest from 29 vineyards in six key wine regions across three states in the northeastern United States. To specifically evaluate the contribution of diverse microbial populations, microorganisms were collected from each grape juice sample, then inoculated into an identical, sterile grape juice. Samples were taken throughout fermentation to monitor fermentation kinetics and population dynamics using metagenomic sequencing, while chemical and sensory analysis was conducted on the finished wines. The quantitative effects of inoculation timing on the chemical and sensory properties of the resulting wines were also evaluated. These results will provide winemakers with applicable knowledge for making data-driven decisions during wine production, including risk mitigation.

Funding Support: E & J Gallo Winery. Startup funds provided by Cornell University