Lambic. Gueuze. Wild Ale. Oud Bruin. Flanders Red. Berliner Weisse. Lately, when I belly up to new and familiar bars alike and begin dissecting the beer offerings, I hunt for these terms like X's on a treasure map. They're among the handful of markers in the world of beers that signify sour. And, I confess, I've become obsessed with the whole lot of them.
Sour beers are exactly what they sound like: they belong to a style of suds deliberately made to present with acidity—often boldly so. Sours have, in my mind, always stood alone among the numerous classes of beer for that reason, even while occasionally sharing some traits with, say, their dry and hoppy or malty and cereal cousins. To my palate, the acidity of a sour beer is generally more acetic than citric; in other words, you might detect flavors akin to cider or balsamic vinegar over any hints of lemon or grapefruit. Sours can be sharply tart, fragrantly fruity, caramel sweet, wine-like, even herbal and vegetal. Indeed, sours are an unruly pack, resistant to hard-and-fast characterization. The more sours I try, the more impressed I become at the breadth of their range of flavors. And it's easy to understand how they developed these freewheeling personalities when you examine the history of their making.
Take Lambic. In Belgium, long a hotbed for sour-beer-making, brewers found that exposing nascent wort to the open air could foster "spontaneous" fermentation. Basically, the airborne yeasts and other bacteria present in the region (most notably Lactobacillus, Brettanomyces, and Pediococcus, which you can read more about here) were allowed to float into and take up residence within these breweries and thus get into the wort. All of these wily agents have a hand in shaping a Lambic's flavor—hence the term "Wild Ale."
This approach to fermentation can take a long time. On top of that, many sour beers are also barrel-aged for up to several years. These factors in part can make sours more precious (read: expensive) than their counterparts at the bar; large-format bottles of Lambic and Gueuze, for instance, can cost as much as decent wine. But if you ask me, the payoff is well worth it.
It could be their sometimes-elevated price, it could be their rarity, it could be their unusual taste, or a combination of all the above, but sours are simply not as easy to come by as an obsessive like me would hope. Thankfully, there's a cohort of ambitious, beer-focused bars in Chicago that not only stock their cellars with obscure and intriguing large-format sours, but also reliably devote one or two tap lines to the tart stuff—which provides an inexpensive entrée into this rich and dynamic style of beer. Check out the slideshow for eight great bars in Chicago that traffic in sour beer of all sorts »