Sour beers have become huge in the past couple years, which weirdly makes Trappist monks the biggest hipsters in the beer world, considering they've been making them for centuries. Now that most major American breweries are at least dabbling in the sour arts, now's as good a time as any to learn what the hell all these beers are about. For a little lesson in the science of sour -- and, more crucially, a list of the best old- and new-school versions out there -- we hit up resident beer expert Zach Mack of New York's ABC Beer Co. and Governors Island Beer Co with all our sour questions. Pucker up: this lesson is going to be delicious.
What is it that makes beer sour?
As with most food discoveries, you could say that traditional sour beers come around by way of a misunderstanding of the world and sheer accidental luck. Way back when, beers were stored in wooden barrels or open-air vessels known as cool ships while fermenting. The staves of the barrels and the air around them, unbeknownst to the pre-Pasteur brewers of the day, were home to a host of microorganisms, wild yeast, and bacteria that would play their own part in the chemical reactions taking place as the beer aged for months (or years).
So it’s that simple?!
Actually, here’s where things get a little tricky. Sour beers come about by different microflora that are responsible for different sets of resulting tastes: lactobacillus bacteria (lovingly referred to as “lacto” in the beer world) creates lactic acid, which results in the relatively clean lemony-tart puckering sour you recognize in beers; pediococcus bacteria (which also gets a cute nickname: pedio), which also creates tart lactic acid but also brings funkier side notes; acetobacter (which *DOESN’T* get a cutesy nickname, which sucks!), the same bacteria that turns wine into vinegar and creates acetic acid, giving (surprise!) sour vinegar flavors; and brettanomyces, a wild yeast (woo, outlier!) known as “brett” for short that creates a drier, funkier set of flavors.
Hoo boy! That’s a lot to remember. And yes, there’s a whole textbook’s worth of microbiology and cell biology jammed into a paragraph there, but what’s most important to know is the basic flavors that each is responsible for. After all, in many cases, these work in conjunction with one another (especially brettanomyces and pediococcus). Remember, it all started by absentmindedly dumping a bunch of beer into barrels that produced a (somewhat unintentional) sour result. And it wasn’t even until the mid-19th century that Louis Pasteur could prove these cells existed, let alone isolated what they did. Kind of puts the whole idea of ordering up cell cultures from a modern lab to brew a batch of beer into perspective.