One may ask, “Who is this “Brett” character we keep hearing about at the local pub, craft brewery, or bottle share?” No, not that frat guy who used to just show up at all of your college parties, shot-gun all of your macro lagers, and piss in your linen closet; “Brett” is short for “Brettanomyces” which is a wild yeast responsible for all of your favorite saisons, lambics, and other wild or mixed fermentation beers.
Often referred to as “Brett” or sometimes “Bretta”, Brettanomyces is a genus of yeast in the same family as Saccromyces, or your regular brewing yeast. The name comes from the Greek words “Brettano” meaning “British” and “Myces” meaning fungus, because when discovered, it was determined to be the culprit of which gave the classic British stock ales their unique twang.
Brettanomyces was first discovered in 1889 and then again in 1899 by brewing scientist at St. James Gate Brewery, or more familiar to most as the people who brew Guinness, but it was first published by Niels Hjelte Claussen from the famous Carlsberg Brewery in 1904 while he was researching the unique yeast as the cause of spoilage in English ales. He cultured the strain from British ales that were showing signs of a sluggish and unanticipated secondary fermentation. Claussen went about trying to recreate the flavor profile of these classic English ales by strategically pitching his Brettanomyces culture, sometimes with a pure strain of Saccromyces, and sometimes after the primary fermentation with Saccharomyces had completed. It is thought that Brettanomyces separated from the now traditional Saccromyces strain over 200 million years ago. It was later patented by Claussen (UK Patent GB190328184) which would be the first patent of a microorganism in history… pretty cool, huh!
So you now might be saying, “OK…cool. Some old dead guys found a weird yeast… What does it have to do with my beer?” Glad you asked! So Brett… yeah, so were just gonna skip the formalities from here on out and just drop the “anomyces”, once was (and still kinda is) considered a spoilage microorganism. Wineries, cideries, cheese makers, and even commercial breweries consider it a pest and try extremely hard through very diligent means of cleaning and sanitation to keep our lovely but misunderstood friend from their finished products because it produces flavors and aromas in these products that are not intended. So when is our friend Brett actually welcome? Well, some breweries in Belgium have been utilizing open fermentation for centuries to produce your favorite lambics and guezes and have been harnessing the powers of Brett for the good of beer. Other styles like saisions, Flander’s Red and Brown Ales, Oud Bruins, and more recently, the wild fermentation works of creative and cutting edge American Craft Breweries have been putting the fear aside and accepting Brett into their breweries and creating works of art.
It is a common saying that “brewers don’t make beer but the yeast do”. With traditional saccromyces, whether in the form of Saccharomyces Cerevisiae (Ale Yeast) or Saccharomyces Pastorianus (Lager Yeast) the brewer has some control and has an idea what to expect. When Brett is in the equation, there’s no telling. Most commercial breweries, wineries, and cideries use pure cultures of Saccharomyces in their fermentable beverages which produce the consistent and desirable flavors and aromas that are expected. Incorporating Brett into a beer can add layers of complexity that would not be possible with regular yeast and allows a brewer to showcase a sense of craftsmanship and skill. BUT… be warned, Brett is wild and cannot be trusted. It can also turn a well planned and executed beer into a gusher, bottle bomb, or even worse, a drain pour.
Brett can be such a bastard to the producers of fine artisanal products such as beer, wine, cheese, and cider because it is all around us. Brett is commonly found on the skins of fruit, and can be transported by insects and this is why wineries try so hard to keep them out of their wine. If Brett is introduced into wooden barrels, it can borough itself up to 8mm into the wood and is even capable of consuming cellibiose (wood sugar). Once a barrel is inoculated with Brett, it is next to impossible to eradicate it. But because of this fact, craft breweries will intentionally inoculate their wooden barrels or foeders with Brett, sometimes along with bacteria such as pediococus and lactobaccilus and use them to create a unique habitat for microflor for funking and/or souring their beer.
Brett has a boat load of flavor and aroma descriptors, some more pleasant than others… and some just downright off-putting. When referring to a beer fermented with Brett, some will regularly use words like, barnyard, band-aid, solventy, buttery, burnt plastic, wet leather, horse blanket, smokey, nutty, cat piss, foot odor, and medicinal. But on the other side of the coin, wonderful flavors and aromas such as tropical fruit, earthy, spice, rose, funk, pineapple, biscuit, stone fruit, hay, apple, floral, citrus, cracker, and clove can be recognized.
Brett is not an All Star athlete like its Saccromyces relative. It works slower and is easily out competed by the pure strain workhorses of regular yeast. But don’t think Brett is going to just give up. It is more resourceful and enduring than its Sacro cousin. It can produce Acetic Acid (vinegar) in aerobic (presence of oxygen) conditions, in an effort to drop the pH of the environment to make it uninhabitable by other competing microorganisms. It is also theorized that it produces a lot of those fruity esters, similar to those associated with ripe fruit, to attract hungry flying insects that will unknowingly transport it to its next source of food. Sometimes it will form a pellicle, which looks like a white, nasty fuzzy film of slime on top of the liquid it is fermenting that some believe to protect itself from outside competitors like Acetobacter and other organisms as well as get closer to an oxygen source. Brett can break down complex sugars and organic matter that Saccro cannot, such as lactose (milk sugar), cellobiose (wood sugar), and even glycosides which can be broken down from compounds found in hops, fruits, fruit pits, and spices. Brett is very alcohol tolerant and can live in concentrations as high as 14-15% ABV and a pH as low as 2%, and can withstand fermentation temperatures as high as 90*F! This is why our friend Brett has been intensely researched in the bio-ethanol field.
Now that we have a basic understating of the misunderstood wild yeast known as Brett, we can hopefully begin to appreciate him. A lot of breweries are still living in fear of the Brett, but with standard sanitation practices, along with using separate equipment for porous and hard to clean items like rubber hoses, gaskets, and what not, one should be able to produce wild and “tame” beers in the same facility… whether it be your kitchen or a 60 BBL brew house. So next time you’re at your neighborhood brewery or craft beer bar, order yourself a local wild ale and embrace the funk!