Brett Beer

What is Brett Beer? Brett Beer is a modern American craft style defined by fermentation with Brettanomyces yeast, classified by the BJCP as style 28A within Category 28, American Wild Ale. Unlike traditional Belgian wild ales such as lambic or Flanders Red, where Brett works alongside lactic and acetic bacteria to produce pronounced sourness, Brett Beer is deliberately dry and only mildly funky rather than overtly sour. Its vital statistics, including ABV, gravity, and bitterness, are intentionally variable, since the style inherits its parameters from whatever base beer the brewer chooses. The result is a flexible category in which Brettanomyces character expresses itself as fruit, light funk, and high attenuation rather than as the sharp acidity of older European wild ales.

Yeast, Fermentation, and Flavor

Brettanomyces is an attenuative yeast genus first isolated in 1889 at the Kalinkin Brewery in St. Petersburg and formally described by N. Hjelte Claussen at Carlsberg in 1904, giving it the distinction of being the first patented microorganism in history. The genus produces a signature set of flavor compounds, most notably 4-ethylphenol, associated with band-aid, barnyard, and horse blanket notes, 4-ethylguaiacol, which contributes clove, bacon, and smoke, and isovaleric acid, which lends a cheesy, sweaty edge. Common brewing species include B. bruxellensis, B. claussenii, and B. anomalus, and strain choice matters: B. claussenii fermented warm, for example, tends to push the beer toward peach.

The style permits three fermentation approaches. A brewer can ferment first with Saccharomyces and then add Brett in secondary or at bottling, run a fermentation with both yeasts together from the start, or use 100% Brett as the sole primary yeast. Entrants in competition must declare when 100% Brett primary is used, because those beers tend to be cleaner and less funky than Brett-finished beers, where the yeast feeds on Saccharomyces-derived phenolic precursors in a more acidic, post-primary environment around pH 4.2.

Tasting Profile and Notable Examples

Compared to the same base style fermented with Saccharomyces alone, Brett Beer is drier, more highly attenuated, lighter in body, fruitier, and only mildly funky. Young examples lead with pome, stone, and tropical fruit character, while barnyard, wet hay, and leather notes develop with age but should never dominate. The overall impression is a balanced, modern reinterpretation of wild fermentation rather than a return to the intense sourness of older Belgian traditions.

The category emerged in American craft brewing after roughly 2000, inspired by Belgian wild ales and by historical English stock ales that often contained Brett. Port Brewing's Mo Betta Bretta is frequently cited as an early celebrated example. BJCP commercial benchmarks include Boulevard Saison-Brett, Hill Farmstead Arthur, Logsdon Seizoen Bretta, Russian River Sanctification, The Bruery Saison Rue, and Victory Helios, all of which illustrate how Brettanomyces can shape a beer without tipping it into the territory of lambic, gueuze, Orval, or oud bruin.