Brett Short for Brettanomyces, is a wild yeast strain, not bacteria, used in fermenting beer and giving the beer a distinct barnyard funk flavor. It will ferment beer the same as your typical brewers yeast (Saccharomyces), except at a much slower rate. It could take months for Brett to display its full characters. There are a few different strains of Brett, each one producing different flavors from tropical and fruity, to a wet horse, dirt, earth, and musty barnyard, and will usually have some sort of tartness to it. Sometimes multiple strains of Brett are used in a single beer to produce different characteristics. “Saccharomyces is like a dog and Brett is like a cat. It’s a little less predictable. It’s going to do its own thing; it’s not going to come when you call it and sit when you say sit. If you can respect its individuality and suggest rather than dictate what it does in your fermentation, it can reward the brewer and the drinker.” explained by, Michael Dawson, brand manager at Wyeast Laboratories, a supplier of liquid brewing cultures. Some brewers will use a bacteria such as Pediococcus (pedio), or Lactobacillus (lacto) in conjunction with Brett to add a bit of fuel for the Brett, but also developing new flavors, and they will drive down the beers ph level causing it to have more of a sour taste. The pedio will help add those funky barnyard flavors and add a pretty harsh sourness to the beer, while lacto is a bit more neutral and will lend a cleaner, softer sourness to the beer.
So there you have it, Brett is just a strain of yeast used to give beer a very unique flavor profile when compared to Saccharomyces, your most common brewers yeast. A great example of a beer fermented with Brett is Orval by Brasserie d’Orval. This beer is brewed exclusively from spring water, barley malt, hop cones, candy sugar, and yeast. The aroma and the fine taste are due more to the hop cones and the yeast than to the malt that is used. Orval Brewery is a Belgian trappist brewery located within the walls of the Abbaye Notre-Dame d’Orval in the Gaume region of Belgium. The brewery only produces two Trappist beers, Orval and Petite Orval. Orval adds the Brett during the bottling stage giving the beer a second fermentation inside the bottle. Grab two bottles, drink one fresh, and age one for six months or so and see how this beers flavor profile will change over time. This beer is constantly changing with time, and no two Orval beers will ever taste exactly the same. A few other beers with Brett used in them that may be easier to find on your local shelf are Little Brett by Allagash Brewing, Saison Brett by Boulevard Brewing, and Elder Brett by Epic Brewing.