Beer

This Beer Is Made With a Wine-Spoiling Yeast — And It's Delicious

Step aside, traditional beer: There's an ancient yeast that's having a renaissance. While some loathe it, others embrace it — either way, it's causing quite a stir. Brettanomyces, or "Brett" to those who know it, has been around for centuries. As our love for small-batch craft beer has picked up, so has the re-introduction of this critical ingredient. Known to produce a funky and unpredictable bouquet of flavors, it's historically been the enemy of winemakers. But these days, some beer brewers welcome it with open arms.

The Science Behind the Craft

The process of making beer is pretty simple. You start with a starch, usually a grain like barley, add some hops, and top it off with boiling water. Later on, yeast and sometimes a special type of bacteria or two are added. If all things go according to plan, a tasty alcoholic libation with a complex array of flavors and aromas results.

The key ingredients of beer might be simple, but their varieties and combinations are virtually endless. Yeast, for example, comes in so many forms that some breweries keep a microbiologist on staff just to wrangle them. Brettanomyces is a yeast (or group of yeasts, known as a genus) that's unlike those carefully cultivated varieties. It's known as a "wild" yeast, as it grows naturally on fruit skins and can be found floating around in wine- and beer-making environments entirely by accident. This yeast acts similarly to other common yeasts used to make beer, but it can either create magic or wreak havoc on the final product.

Whether added intentionally or not, Brett — and any yeast — uses sugar in the grain as energy and leaves behind a few important things: alcohol (woo!), carbon dioxide (bubbles!), and flavor (yum!). It's the flavor-inducing byproducts of the yeast that make it a topic of discussion among brewers and vintners alike.

Colonies of yeast Brettanomyces bruxellensis on agar plates containing phloxine B.

Loved and Loathed

With flavors associated with Brettanomyces ranging from funkiness and light tartness to aromas of stinky feet and "sweaty horse blanket," it's easy to understand how such a yeast could be tantalizing and intimidating all at once. Known as a slow fermenting yeast, Brett takes some time to get working. This can make it a bit difficult to regulate, and without careful attention, it can continue fermenting long past its intended time in the bottle. Besides resulting in too much carbonation, improperly managed Brett can also negatively affect the final taste.

Another reason Brett is commonly despised has to do with how easily it can transfer from one place to another. If a brewer uses Brett in one batch of a beer, it's highly likely that the yeast will end up in other batches in the same vicinity. That's why equipment from a Brett batch must be thoroughly sterilized before being used for a non-Brett beer.

Brettanomyces has been around for thousands of years, historically making its purposeful way into certain styles of beer thanks to brewers leaving the windows open and inviting the microbes in for a visit. These days, its introduction is more controlled but no less creative. Depending on your taste preferences, a Brett beer may be a hit or not so much. Most commonly incorporated in styles such as Lambic, Gueuze, Saison, and Flemish Red Ale, this yeast packs a lot of punch and is definitely worth a try. Whether you end up with a perfectly tart beer or something more along the lines of smelly feet is up to you. Cheers!

Genetically Engineering the Perfect Beer

Written by Ashleigh Papp July 13, 2018

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