For a long time, before Louis Pasteur came along and ruined everything, beer was sour by nature. The product of poor sanitation, ambient yeast and crowds of bacteria in the cracks of barrel staves, sour beer was infected by accident, not by choice.
Now, it’s the other way around. A resurgent taste for sour is energizing brewers to revisit Old World methods with a new and experimental sensibility, producing tart beers of winelike complexity, underpinned by the occasional barnyard funk. Look no further than the infinite taps in SF’s outpost of the famed Danish gypsy brewer Mikkeller, the well-stocked cellar of oddities at Monk’s Kettle and the dreamy shelves of City Beer and Healthy Spirits.
The remarkable thing about sour beers is the sheer multiplicity of shades inside that descriptor: tart, punchy, sulphuric, sharp, farmy. Some of them creep up slowly, a soft and sparkling brew that slips in a final tangy punch. Others start with a belly flop into a goat barn full of Sour Patch kids. Depending on who you talk to, that could be a great thing.
Sour beers swing between acidic and funky, malty and lean. The trademark “horse blanket” note of some sours comes courtesy of a wild yeast class called Brettanomyces, or “brett” to those in the know. The funk lives in the rafters of old Belgian breweries, and is so sacred to some—like Cantillon—that they’d never consider moving across the street for fear the magic would be lost. It’s a kind of hyper-terroirism mixed with superstition. In the US, though, modern brewers inoculate more deliberately, producing “wild ales” with strains often purchased from a lab. The acid that develops—acetic or lactic—also depends on the brewer’s choice of bacteria.
For wine drinkers considering a foray into sours, look to Birra Del Borgo’s Caos, a saison mixed with Malvasia grape must and fermented with champagne yeast. Delicate, aromatic and only subtly sour, Caos fronts as a winelike aperitif. Available at Mikkeller Bar.
Troublesome Brewery’s Gose is likewise delicate, brewed with sea salt and coriander for a nice, clean salinity that pairs well with seafood. The Berliner Style Weiss from Gasthaus and Gosebrauerei Bayerischer Bahnhof is also mild and refreshing, and a true representation of Berlin-style sour: low in alcohol, sweetened lightly with woodruff syrup and tart in a way that tickles. Both can be found at Monk’s Kettle and make excellent summertime drinking.
Bolder venturing leads to geuze. Brewing conventional beer is already a gamble, but leaving its fate to the creatures crawling in your barn rafters is about as much of a crapshoot as it gets. This style—spontaneous fermentation—begets a beer called lambic, a Belgian genre we’ve come to know mostly as cloying and fruitlike thanks to some breweries’ habit of heavy sweetening. Traditional lambic is considerably dryer, more winelike, and a bit sour. Geuze is a blend of three lambics, typically 1, 2 and 3 years old. It’s both a parachute technique to help brewers balance the enthusiastic or offending character of beers year after year, but it’s also a terrific way to control the craft.
The Oude Geuze by Brouwerij Fontenen, available at Monk’s Kettle, is an approachable, lingering geuze that unfolds slowly. A wilder iteration, Betelgeuze, is the collaborative brainchild of Mikkeller Bar and another Danish microbrewery, To ØI. Clear, bright and minimally sour, Betelgeuze holds up with an oaky backbone and just a whisper of barnyard funk. For a new initiate, it’s a toe in the water.
When it comes to sours, lopsidedness has its merit. Take, for example, the Funky Gold Amarillo from notoriously experimental Prairie Artisan Ales. It’s a bit like curling up in a barn blanket to eat old Granny Smith apples, but it offers up intoxicating, ephemeral grapefruit notes and a wildly aromatic burst of hops at the end. It’s the kind of kaleidoscope you can’t miss.
For a better balance, try the bench-mark Red Flanders Ale, Rodenbach. Full-bodied, complex and sweet in a rounded, lipsmacking way, the beer inspired New Belgium Brewery to brew a lean and punchy counterpart: La Folie. Find them both at City Beer. My favorite red sour at the moment is Bockor Brewery’s Cuvee Des Jacobins Rouge at Mikkeller Bar: berrylike and puckery upfront, finishing with a beautiful and lingering, shimmering sweetness.
A longer stride into the weird, deep chasms of sour beer will land you in experimental stout territory, where Anchorage Brewing Company’s Anadromous is waiting. The black
sour ale takes a robust, sour turn upfront, and softens with the silky, residual tannins of the pinot barrels it was aged in. At Mikkeller Bar, a more accessible version sits on tap: the magical Haandbakk ale from Norwegian brewery Haandbryggeriet. Rich, nutty and sweetly sour, it is a rare instance of a dark beer with the perfect acidity to balance a meaty dinner.
Old World recipes have certainly inspired the new movement into sour beer, but it’s the new twists that will keep its momentum going. Mikkeller Bar makes an entire line of spontaneously fermented beers (the Spontan series), an experimental roster of fruits mixed into the same lambic base. It’s these leaps into the abyss that make a seat at the brewery’s Tenderloin bar the best place to furnish your own sour education, and a good spot to grapple with the existential confusion of a taste bank that is as offensive as it is irresistible.