That funky, earthy flavor in craft beer has left countless beer lovers confused and disappointed, but it’s one of brewing’s most prized characteristics.
Brett beer intimidates newcomers with its polarizing “horse blanket” reputation, yet it’s behind some of the world’s most expensive and sought-after brews. The problem isn’t the beer—it’s understanding what you’re tasting and why it matters.
This reveals the fascinating science behind Brettanomyces, explores legendary styles from Belgian lambics to modern American wild ales, and gives you the knowledge to appreciate what makes these “flawed” beers brilliant.
Table of Contents
- History & Origins
- What Is Brettanomyces?
- Flavor Profile
- Brewing Methods
- Popular Styles
- Top Examples & Breweries
- Food Pairings
- Ready to Get Funky?
- FAQs
History & Origins
Brett beer traces its roots back to the ancient farmhouse traditions of Belgium, where wild fermentation was simply how beer was made before modern sanitation practices took over. This wild yeast has been fermenting beers for centuries, particularly in the Brussels region and the rural Senne River Valley, where lambic beers have been brewed since the 13th century, making them one of the oldest beer styles in the world.
The term Brettanomyces comes from the Greek for “British fungus,” named after N. Hjelte Claussen at the Carlsberg brewery first published a description in 1904, though it was first isolated from English beer in 1889. What’s fascinating is that Brettanomyces was typically present in 1800s English aged beers such as stock ales, pale ales, porters, and barrel-aged IPAs that were shipped to India, and it was considered an important component of the flavor profile of these beers.
Despite what modern eyes might see as a pastoral and primitive 19th-century Walloon countryside, this was actually the most industrialized region of the European continent. The timeline from traditional farmhouse brewing to modern craft applications shows how brewers eventually moved from accidental wild fermentation to intentional cultivation of these complex yeasts.
Related: Dry Yeast vs Liquid Yeast: Which is Better?
What Is Brettanomyces?
Think of Brettanomyces as the rebel cousin of regular brewing yeast. Brettanomyces is a genus of wild yeast found in the natural environment on surfaces such as the skin of fruit, and it’s adapted to beer and wine in different ways than Saccharomyces, resulting in a yeast that is much slower fermenting and worse at handling anaerobic conditions, but much better at surviving in low-nutrient environments.
When we talk about Brett in beer, we mostly talk about two species: Brettanomyces bruxellensis and Brettanomyces anomalus. Brettanomyces bruxellensis is a classic strain used for secondary fermentation in Belgian-style beers such as lambics and creates a medium-intensity, earth-forward character in finished beer.
Under the microscope, the cellular morphology of the yeast can vary from ovoid to long, “sausage” shaped cells. What makes Brett special is its voracious appetite—unlike regular yeast that gives up after eating the simple sugars, Brett is voracious and will slowly but steadily ferment straight through even the thickest of wort. Brett is kind of the cockroach of the brewing world—it’s incredibly resilient and persistent.
Flavor Profile
Here’s where things get interesting—and polarizing. The beers have a slightly sour, earthy character. Some have described them as having a “barnyard” or “wet horse blanket” flavor. Descriptions range from “floral” even “earthy” to “horse-blanket,” and where the winemaker blanches, the craft brewer rushes in.
The science behind the funk is fascinating. The major secondary metabolites of B. bruxellensis fermentation have been identified as the ethyl phenols, alcohols, and esters. The flavors that Brett creates are derived mostly from activity on phenols from the malt and esterification of acids and alcohols.
Picture a flavor wheel where traditional Brettanomyces characters include horsey, smoky and spicy flavors, but after primary fermentation there will be some fruity esters like pineapple and stone fruit present, but given many weeks or even months, Brettanomyces will begin to build up a complex profile with notes of hay, dried flowers, dried tobacco, leather, and other spicy and peppery phenolic aromas.
Key Brett Flavor Characteristics:
- Barnyard funk – The classic “horse blanket” or “wet leather” notes
- Fruity esters – Pineapple, stone fruit, and tropical flavors
- Earthy phenols – Hay, dried flowers, and dried tobacco
- Spicy notes – Peppery and smoky characteristics
- Tart acidity – Mild sourness from acetic acid production
- Dry finish – Brett consumes more sugars, leaving less sweetness
What’s crucial to understand is that 100 percent Brett fermentations are generally cleaner than beers that use Brett only in secondary. So if you want funk, leather, and horses, ferment first with the ale strain of your choice, and then follow it up with some Brettanomyces in secondary.
Brewing Methods
Brett brewing isn’t rocket science, but it does require patience and understanding. There are three main approaches: primary fermentation, secondary fermentation, and mixed fermentation.
Most brewers add Brett in secondary (after adding Saccharomyces in primary), and with the strains they use, they give it two weeks of conditioning and see the pellicle forming, pH dropping, and flavor development occurring. For primary fermentation, Chad Yakobson of Crooked Stave aims for a lager-like 1.25M cells/ml•°P pitching rate.
When making a beer that will spend a long time in barrels, brewers do a higher mash temperature, around 158°F, to add more dextrins to the wort so the Brett has something to chew on during its long fermentation. For shorter fermentations, brewers use a low mash temp, around 146°F, and won’t go over 13°Plato for the starting gravity.
Most brewers use three different yeasts in three different fermentations: a Belgian strain for primary fermentation, then secondary with Brett in small barrels, and lastly bottle conditioning with wine yeast. Brett beers can be in primary and secondary for periods of longer than 6-9 months—this isn’t a style for impatient brewers.
Popular Styles
Brett shows up in some of the most revered beer styles in the world. Gueuze and other lambic beers owe their unique flavor profiles to Brettanomyces, as do wild yeast saison or farmhouse styles, and it is also found in Oud Bruin and Flanders red ale.
Traditional Belgian Styles
- Lambic – Spontaneously fermented with wild Brett and bacteria
- Gueuze – Blended young and old lambics for complexity
- Kriek – Lambic fermented with cherries for fruity tartness
- Saison – Farmhouse ales with Brett adding rustic character
- Flanders Red Ale – Aged in oak with Brett, creating wine-like sourness
- Oud Bruin – Dark, malty base with Brett providing gentle funk
Saison was historically brewed with low alcohol levels, but modern productions of the style have moderate to high levels of alcohol and are generally classified as farmhouse ales. Commercial examples include Boulevard Saison Brett, Hill Farmstead Arthur, Logsdon Seizoen Bretta, Russian River Sanctification, The Bruery Saison Rue, and Victory Helios.
The modern craft movement has given birth to Brett IPAs, which pitch Brett in place of Saccharomyces for primary fermentation and produce vivid flavor and aroma compounds, notably esters, which taste like fruit. Some Brett strains produce especially tropical esters, much like American hops.
Modern American Adaptations
- Brett IPA – Tropical fruit esters complement hoppy bitterness
- Sour IPA – Combines Brett tartness with citrusy hop character
- American Wild Ale – Broad category for Brett-forward experimental beers
- New England Brett – Hazy, juicy IPAs with Brett’s fruity complexity
Sour beer styles include Belgian lambics and Flanders red ale, where B. bruxellensis plays a key role in the production of typical Belgian beer styles such as lambic, Flanders red ales, gueuze, and kriek. Kriek uses cherries, while Framboise uses raspberries in the traditional fruit lambic variations.
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Top Examples & Breweries
American Breweries
American breweries have developed lambic-style interpretations with significant commercial success. Jester King in Texas produces 8 of the top 75 Wild Ales ranked on BeerAdvocate and was ranked among the Top 5 Small Breweries in the World by Craft Beer and Brewing magazine. The brewery specializes in sour and wild fermented beers.
Allagash Brewing Company produces Golden Brett using a proprietary Brettanomyces strain isolated and maintained by the brewery. This controlled wild yeast fermentation produces specific flavor compounds and characteristics.
Belgian Producers
Cantillon operates from Brussels at the Cantillon Brouwerij and produces traditional unblended lambic using spontaneous fermentation. The facility also houses the Brussels Museum of the Gueuze. Cantillon’s production methods follow traditional lambic brewing techniques established in the Pajottenland region.
Orval Trappist Ale incorporates Brettanomyces yeast during the bottling process. This secondary fermentation continues in the bottle, producing ongoing biochemical changes that alter the beer’s flavor profile over time.
Brettanomyces Adoption
B. bruxellensis usage has expanded among American craft breweries, with concentrations in Maine, California, and Colorado. Breweries utilizing this yeast strain include Jolly Pumpkin Artisan Ales, Port Brewing Company, Sierra Nevada Brewing Company, Russian River Brewing Company, and New Belgium Brewing Company. These breweries employ B. bruxellensis for controlled wild fermentation to produce specific flavor compounds, including esters, phenols, and organic acids.
Food Pairings
- Aged Cheeses: The earthy, barnyard character of Brett beers complements aged varieties. Mathilda pairs well with Upland’s Pleasant Ridge Reserve. Blue cheese works particularly effectively—its pungent, salty profile complements Brett’s funky notes without overwhelming them.
- Charcuterie: Prosciutto, salami, and other cured meats provide ideal accompaniments. The salt and fat content balance Brett’s natural acidity while enhancing earthy flavor compounds.
- Specialty Pairings: Cantillon’s Quintessence events demonstrate optimal combinations, featuring vintage beers with charcuterie plates and specialty items like Brasserie Dupont cheese made with Cantillon Gueuze.
- Citrus and Desserts: Cheese plates highlight citrus notes and fruit characteristics in Brett beers. Creamy desserts offer contrast to sour elements. Citrus fruits create harmonious pairings where acidity levels complement rather than compete, producing bright combinations that cleanse the palate between tastings.
Ready to Get Funky?
Brett beer isn’t just weird—it’s wonderfully wild. Those “barnyard” flavors aren’t flaws; they’re features that create some of the world’s most complex brews. From tropical Brett IPAs to earthy lambics, you now know what makes each style tick.
The science is simple: Brett eats everything regular yeast can’t, creating months of flavor development. Breweries like Jester King and Cantillon aren’t just making beer—they’re crafting liquid art. Pair it with aged cheese and charcuterie for the ultimate experience.
Bottom line: Brett requires patience and an open mind, but rewards you with centuries of brewing tradition in every funky sip. Time to grab a glass and get wild!
FAQs
Brett is short for Brettanomyces, a wild yeast genus that creates complex flavors in beer through slow fermentation. Unlike regular brewing yeast, Brett continues eating sugars that other yeasts can’t consume, producing distinctive earthy, funky, and tart characteristics. It’s found naturally on fruit skins and has been used in traditional Belgian brewing for centuries.
Brett refers to Brettanomyces yeast, which means “British fungus” in Greek. This wild yeast was first isolated from English beer in 1889 and was commonly found in aged English ales like porters and IPAs. Today, Brett represents a return to traditional wild fermentation methods that create unique, complex flavor profiles in craft beer.
Brett beer has a distinctive “barnyard” or “horse blanket” funk with earthy, leather-like notes. You’ll also taste fruity esters like pineapple and stone fruit, along with dried flowers, hay, and spicy phenols. The flavor develops over months, creating layers of complexity with mild tartness and a dry finish that’s both polarizing and addictive.
While the article doesn’t specify the single most expensive beer globally, it mentions that Brett-fermented beers like Belgian lambics and gueuze are among the world’s most expensive and sought-after brews. Traditional producers like Cantillon create limited quantities using time-intensive methods, making authentic Brett beers highly valuable to collectors and enthusiasts worldwide.