All sorts of odd words show up on our bottles and cans and tap lists these days. Some of them even mean something, though it can take some geeky detective work to figure out how these ingredients are supposed to bring us added pleasure. Anyway, who is this “Brett” guy?
Briefly, Brett is short for Brettanomyces, a type of yeast found in the wild—on the skins of fruits, for example. Winemakers fear it as a culprit in spoilage, although a few allow a bit of it for house character. Modern brewers also tend to avoid Brettanomyces, preferring to control fermentation with aseptic conditions and pure yeasts.
But, by and large, it is perfectly cool to harvest wild yeast and simulate old-fashioned beers descended from the days when microscopes were rare and these things were not well understood. And, it’s a growing trend. There are festivals dedicated to Brett—like the Carnivale Brettanomyces in Amsterdam—and there are breweries that give it pride of place—notably Denver’s Crooked Stave, helmed by yeast expert Chad Yakobson. He even wrote the Brettanomyces entry in the “Oxford Companion to Beer”: “Craft brewers casually refer to the yeast as ‘Brett,’ a name that sounds appropriately like an old friend.”
Indeed more brewers are getting friendly with it. In deciding how best to make use of Brett, they can draw inspiration from each other, or from history.
Its name means “British fungus,” since scientists discovered it while studying the souring of aged British ales. It’s also an important player in the acidic lambics of Brussels and Pajottenland, and the Trappist brewery at Orval famously uses it for bottle conditioning. In Germany, modern Berliner Weisse tends to have a straightforward lactic acidity; beer historian Ron Pattinson believes that older examples had greater depth thanks to the presence of Brett.
So what does it do to our beer? How does it smell, and how does it taste?
The answer depends a lot on how it’s used. When used for secondary fermentation—that is, the brewer first uses a normal yeast, only later adding Brett—the effects can be subtle, though they can grow and evolve as the beer ages. Meanwhile, it’s becoming more common for brewers to use Brettanomyces for primary fermentation, which can produce completely different, less subtle aromatic traits.
But what are those traits? If forced to choose a word to sum it up, I’d say “rustic.” Some call it “funk.” Anyway, we can be more specific.
Depending on the strain of Brett and when it enters the brewing process, these are adjectives you might hear—or better yet, discover for yourself: leather, musty, pineapple, tropical fruit or floral. Those are some of the nice ones. It can also have some not-nice smells, including medicine and bandages. Ideally your local adventurer-brewer will know how to avoid those. Also, a Brett beer is not necessarily sour—again, that depends on how it’s used, and whether certain bacteria are present (on purpose, you hope).
No need to be slavish to the usual flavor descriptors, either. The first time I tasted an authentic gueuze—I hadn’t really learned about Brett yet—I scribbled something down about “musty lemons stuffed into an old gym sock and thrashed around a used bookshop a few times.”
I wasn’t crazy about it, then. But the most rewarding tastes tend to be the ones we acquire.