Beauty and the Yeast
Now we’ve talked about yeast before, albeit in a different context, but frankly I feel like these little buggers require a bit more examination. Yeast, after all, is arguably the most important fungus on the planet. It’s responsible for wine, beer, bread, that “not so fresh feeling”; all the things that make the human condition so unique.
These little microorganisms are ubiquitous, adaptable and their simple presence alerted us to the magic of fermentation. Imagine, if you will – and if you won’t, you can go right back to looking at cats on Reddit – Jeff Abrashvili, a hypothetical Georgian farmer some 8,000 years ago. He is picking delicious grapes, chucking them in a barrel and staving off a mild case of tuberculosis. Then one day, he realizes that these little berries are, for some reason, fizzing like some insane candy that won’t be invented for the better part of Jeff’s time to the present. He eats a few. Then a few more, and all of a sudden he’s got his skirt up over his head riding a mechanical bull in some awful bar in the East Village. Jeff could never have understood that this was because of an endemic species of fungal microorganism that converts sugar into alcohol.
This is the bit that, quite frankly, blows my mind. So you have this fruit that is easily squish-able by hand, yields lots of sugary-sweet juice, and happens to have a microbe living on its skin that can use that juice as fuel for a chemical reaction that leaves us with a $5,500 bottle of Shrieking Egret? This is not insignificant, people. There is a reason we didn’t start with cantaloupe wine.
Now what I have described is the old-school method (Methode vieille école). This goes beyond tradition to the origin of the art form of winemaking. For many, using native yeast is considered the only real way to do it. These wineries take advantage of the fact that they’ve basically set themselves up to be a miniature ecosystem in which colonies of native microorganisms have been living, breeding, rigging micro-elections and violently busting up micro-unions for years. They’re in the vineyard, on the walls, and all over the tasting room and they can help to lend many unique nuances to the wine of any given estate.
The problem is these native yeasts are not very reliable. The primary yeast used in winemaking is Saccharomyces cerevisiae, a hearty little bastard that can withstand high amounts of sulfur and alcohol. This means we can add a little bit of sulfur to the must before we begin fermentation in order to kill off any possible competition, and our little buddies will still be healthy and happy even when the ABV hits 12-15 percent. All that said, there is a much wider range of wild yeasts out there with cool names like Hanseniaspora and Metschnikowia that, while they have to the ability to produce high quality and unique wines, might not be as reliable as our steadfast friend S. Cerevisiae, who will typically pick up the slack after these guys kick the bucket at around 5 percent alcohol. Moreover, going natural means risking interlopers like Brettanomyces getting in and skunking your booze, or a “stuck fermentation,” in which the yeast stalls out too early and you’re forced to try re-inoculating your batch. It’s a pain. Trust me.
Well here in ‘Merica (ok fine, pretty much everywhere in the New World), winemakers aren’t in the mood to chance that sort of thing. Never mind the fact that they don’t have several hundred years worth of fungus to rely upon. So, instead, they turn to cultured yeast: strains of S. Cerevisiae that have been specially bred in laboratories to become the next generation of time traveling super soldiers to emphasize useful qualities such as alcohol resistance, heat generation and flavor profile. These guys have cool names like BDX, Epernay and Enoferm L2226. A lot like grape clones, these cultured yeasts can still trace their lineage back to Old World regions in which they originally developed their nuances.
You’ll notice I didn’t get into the chemical nitty-gritty and talk to you about anaerobic versus aerobic fermentation or the volume of CO2 and ethanol produced relative to the amount of sugar in the solution. I didn’t do that because I like you, dear reader. And I failed chemistry twice, so let’s just let sleeping dogs lie.
So what should the next lesson be? Wanna talk about minerality? Micro-oxygenation? Moscato’s inexplicable popularity in the hip-hop world? Where do we go next?
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