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“This narrative of terroir yeast associated with a specific vineyard or estate has always existed,” says Isabelle Masneuf-Pomarede, professor of viticulture and enology at Bordeaux Sciences Agros’s Institute of Agricultural Sciences.
Masneuf-Pomarede has been involved in yeast research for about 20 years and argues that both winemakers and drinkers tend to glorify the use of indigenous cultures as opposed to commercially available alternatives for the former’s ability to express terroir and bring unique characteristics to wine. Indeed, while a diverse array of yeast strains and bacteria are commonly found in nature, beliefs such as the contribution of indigenous cultures to a wine’s organoleptic complexity and their use as a means to express a vineyard’s unique character encounter considerable academic skepticism.
Other wine professionals maintain that indigenous yeasts bring unique characteristics to wine, even if those strains are difficult to identify.
Commercial yeasts are unique strains that have been isolated from wild and indigenous cultures because of specific phenotypic traits and properties of interest, then propagated on a large scale. Their effect on the vinification process and a wine’s final flavor profile may be somewhat predictable, but they ensure a hiccup-free fermentation and a final product free from undesirable taints.
Indigenous or “wild” yeasts, on the other hand, might cause stuck or sluggish fermentations, off-aromas or, in worst-case scenarios, spoilage. However, their supporters believe that, when handled with care, they translate into greater complexity and in a truer expression of each vineyard’s unique attributes.
“The expression of terroir and the connection between the vineyard and the winery are strengthened by utilizing native ferments,” says Rebekah Wineburg, enologist at Napa Valley’s Quintessa. “And the fermentation microbiology is more complex with native ferments; different strains will dominate the fermentation at various stages, resulting in a more complex wine.”
Masneuf-Pomarede is skeptical that such yeasts are necessarily unique to a given place. “It is not actually demonstrated that winemakers can ever claim that any given yeast is associated with their winery,” she says, highlighting that, at any given time, the same strain or selection may be found across a number of adjacent wineries.