The word “terroir” refers to how soil, climate, topography and local traditions can imprint on a wine — or a cheese or even coffee beans. It’s what makes something taste of its place. The concept can also be applied to mezcal. Ron Cooper, the founder of Del Maguey, has helped prove as much with his single-village bottlings. Each one is unique thanks to the local environment in which it was made. But it’s more than what we can see with the naked eye that impacts mezcal, he says. Cooper is talking about another aspect of terroir that rarely gets mentioned: microbial life.
“Every 300 feet there are different invisible airborne microbes,” he explains. These microscopic organisms, including yeast and bacteria, are found in the nooks and crannies of mezcal distilleries and on the agave plants themselves. (In winemaking, they’re on the skins of grapes.) These are the invisible critters that work to ferment crushed agave so it can later be distilled. But they do more than that, argues Cooper. Because they are responsible for converting sugar into alcohol (“yeasts eat sugar, piss alcohol, and fart carbon dioxide,” he likes to say), they have an impact on flavor.
“Yeast turns sugar into alcohol, but that’s not all it makes,” says Erica Shea, a partner in Brooklyn Brew Shop, known for its sleek homebrewing kits. “Throughout fermentation, it creates a lot of other chemical compounds that contribute to a beer’s flavor.”
When yeasts convert to alcohol, it alters the chemical structure of its liquid environment. This interaction releases new chemical compounds, like esters and phenols, which impart flavors to the final product. Different yeast strains produce different compounds. Luckily, you don’t need a PhD to identify them. In many cases, they can be identified by taste. Esters are known to give off banana candy, pear and green apple flavors. Phenols are responsible for spicier notes, like the signature clove in a German Hefeweizen. And the list of compounds goes on.
“Then there’s wild yeast,” says Shea’s partner, Stephen Valand. “Brettanomyces [or Brett for short] is in the air all around us, and it can create funky horse-blanket flavors. It’s an acquired taste — but tasty nonetheless.”
According to Lucy Joseph, the curator of the Wine Microbe Collection at the Department of Viticulture and Enology at UC Davis, yeasts produce these compounds as a way to detoxify chemicals in their environment. Their aromatic qualities are little more than a happy side effect. But certain researchers speculate that humans evolved to prefer the aromas and flavors of these compounds because they indicate that less toxicity is present.
“There are a lot more wild beer evangelists out there than there used to be — mainly because funky beer is really good.”
In any case, yeasts are not the only microorganisms at work in fermentation. Many red wines and certain whites, like Chardonnay, undergo malolactic fermentation. The bacteria Oenococcus oeni “converts the harsher malic acid to the softer lactic acid and makes the wine more stable and less likely to spoil,” explains Joseph. It can impart spice or smoke to red wines and give whites a buttery character. (Again, think Chardonnay.) As Shea points out, bacteria is also having a moment in beer. The flavors in sour beer result from lactobacillus, the bacteria found in yogurt and other probiotic products.
“The idea that yeast contribute to terroir has been given a lot of credence lately due to research showing that wines from different regions have a microbial fingerprint,” says Joseph. “It would not be unexpected that the geographic and climactic conditions that mark regional character, or the terroir of wines, also affect the microbial populations in those regions.”
This idea of “microbial terroir” inevitably leads us to the question of natural yeasts. Across the wine and spirits industry, natural fermentation is a contentious issue. Proponents swear it’s the only true expression of terroir, that using synthetic or lab-raised yeasts instead of the yeasts that naturally occur in our environment cannot result in a product that truly tastes of its place.
Others, which account for the majority of the industry, claim that relying solely on natural yeasts is unrealistic and inefficient. They can be slow and sometimes don’t complete alcoholic fermentation. Then there are brands that fudge the truth, claiming natural fermentation when in fact they give Mother Nature a little boost.
“There are a lot more wild beer evangelists out there than there used to be — mainly because funky beer is really good,” says Brooklyn Brew Shop’s Valand. “But relatively few breweries do a completely wild fermentation because each batch would take more than a year, and it’d be difficult to produce a consistent beer without a ton of blending between different vintages, which takes practice. This, of course, is changing, and we’ll be seeing more wild breweries (like we already are with cider makers) in the next few years. But they’ll be small batch and not competing for any airport beer contracts anytime soon — which we’re totally cool with.”