With the permeation of “sour” beers into the American craft beer market, there has been a lot of confusion about them. One of the biggest issues surrounding this category of beer is, ironically, categorization. All sour beer is not equal, and in fact, can be wildly, illogically different.
Jay Goodwin of The Rare Barrel says that sour beer brewers in the US need to start coming up with better labels for the different types of beer they’re producing. Some names already exist, gose and it’s close cousin berlinerweisse both have their names and flavor definitions come to us from the Old World whence they came, and largely American brewers have stuck to that definition with their versions.
The difficulty lies in the boundry-pushing, non-traditional sour brewing that’s exploding in America. Without the burden of “this is how we’ve always done it” over their heads, American brewers are looking at sour beer and the bacteria and yeast that create them with a new, almost infant-like innocence. What do you mean we can’t put a 9% traditionally fermented barleywine in a semi-neutral Jack Daniels barrel and age it for six months with a mixed culture of commercially available strains and various bottle dregs? What do you even call something like that on the shelf? (Bentley Brewing Company calls it Fancy Pants).
One sour beer category name several brewers are starting to use is “brett beer.” No, Brett isn’t the name of some bearded, flannelled brewer somewhere in the Pacific Northwest (although it probably is). It’s the nickname brewers have given to brettanomyces, a unique and still not completely understood genus of yeast that produces a set of flavors that, in some circles, are to be avoided at all costs.
In wine making (and the majority of brewing as well), the word brettanomyces means “ruined.” Because it is considered a “wild” yeast, it is most commonly seen as a contaminant. These wild yeasts can result in flavors ranging from “horse blanket” to “barnyard” to “blue cheese.” When these flavors are detected in wine or “clean” beers, it is considered an infection, and the liquid must be dumped and the equipment meticulously cleaned to eradicate the pesky organism.
In sour brewing it’s actually one of the main means of fermentation. While it may be considered a “wild” yeast, certain strains of brett have been cultivated over the generations into an organism not unlike the yeast known and loved by brewers and winemakers, saccharomyces cerevisiae. Under the watchful eye of a good brewer, brettanomyces can ferment a beer from start to finish with none of those “off” flavors.
However, some brewers want those flavors, or at least a version of them. The complexity of flavors that brett can produce are many and varied, and rely upon dozens of factors, from protein concentration, temperature, atmospheric pressure, alcohol percentage, and many more. The results can be a drink that is unlike any other, and when appreciated as it’s own thing, can open the eyes of even the most jaded of drinkers.
The thing is, brett doesn’t always play solo. More often than not, “sour” beers are the result of what is called a “mixed” fermentation. Two other bacteria make up the trio most commonly found in sour beer, pediococcus and lactobacillus. More on them soon.