Before pasteurization, nearly every beer made was touched with some degree of unintentional sour. But since the late nineteenth century, most brewers have tried, with great success, to keep souring agents (a few certain kinds of microbes) out of their beer.
But today sour-on-purpose beer is an increasingly popular, if maddeningly overarching, category of drink. The category of "sour ales" includes many distinctive styles made in many different ways. The difference between a lambic and a Berliner Weisse, for instance, or a gueuze and a Gose, couldn't be greater. With that in mind, here is our guide to the Sour Beers of the World.
Lambic is one of the most complex and singular beer styles in the world. Named for Lembeek, a small village in the pastoral Flemish region of Pajottenland, lambic originated in and around the city of Brussels. Lambic is, at its most basic, a sour wheat ale fermented by wild yeast. But many peculiar components and processes are woven into its production. The wheat is raw rather than malted and makes up 30 to 40 percent of the overall grain bill—an unusually high percentage, even for a wheat beer. The hops are aged for several years—aged to taste oxidized and cheesy, not to add the grapefruity notes you love in your California IPAs. They are more a preservative than bittering agent.
Perhaps the most distinctive aspect of lambic brewing is the use of a koelschip, or coolship, for cooling and inoculating the unfermented beer. During this phase, hot wort (unfermented beer) is pumped into the coolship—a wide, shallow bathtub-like vessel made of metal—and left to cool overnight, uncovered, with the windows or special vents in the brewery's roof left open. This invites microflora to inoculate the beer with the mix of bugs and microorganisms that will eventually cause fermentation. Since the outside air needs to be cool in order to chill down the wort, traditional lambic brewing is confined to fall through early spring (though global warming is actively shifting this historic timeframe).
Once the wort is chilled and populated with wild microorganisms, the liquid is transferred to open wood fermentation vessels where it ferments for many months with the help of myriad yeast strains and bacteria including saccharomyces, enterobacter, pediococcus, and brettanomyces. The result is tart and highly acidic, with aromas of barnyard and animal funk followed by lemon, vinegar, and sharp cider: a challenging beer, to say the least.
Because of these potent (and often objectionable) flavors, most lambic is cut with younger beer, whole or juiced fruits, or even sugar, to balance their flavors. However, some are bottled "unblended," meaning the lambic is from a single vintage and is not cut with fruit or sugar.
Try these: De Cam Oude Lambiek, Cantillon Iris, Vanberg & DeWolf Lambickx (Unblended)
The art of blending lambic is arguably just as—if not more—important as the brewing itself. Many blending houses, or "gueuzerie," don't actually brew beer at all; instead, they source young and old lambic from other producers and concoct their own proprietary beer blends. These blends of old and young lambics are called gueuze (usually pronounced "gooz" but sometimes "ger-za"). Though gueuze does not contain sugar or fruit, it's much more balanced and approachable than pure, unblended lambic. Some gueuzes contain lambic as old as five or six years, but the most common ones are blends of one-, two-, and three-year-old beers. Young lambic softens the overall gueuze and rounds out the harsh, acrid flavors of old lambic, while the fermentable sugars still present in the young lambic create a final fermentation (and high carbonation) in the bottle. Note that despite similar pronunciations, gueuze has absolutely nothing to do with Gose, the German-style sour ale (see below).
One more note: gueuze is pronounced "gooz" if your native tongue is French and "gerza" if it's Dutch. From my experience, almost everyone, including Americans, uses the French pronunciation.
Try these: Drie Fonteinen Oude Geuze, Boon Oude Geuze Mariage Parfait, Cantillon Lou Pepe Gueuze
A note of serving bottle-conditioned lambics: Gueuze and other bottle-conditioned lambics are traditionally aged on their side, causing sediment to accumulate along the length of the bottle. If a bottle-conditioned lambic is pulled directly from storage, it's traditionally poured horizontally from a wicker basket, preventing sediment from redistributing into the liquid. The traditional glassware is a straight-walled tumbler glass, but tulip glasses and snifters are also common.
Fruited lambics are cut with whole, crushed, or juiced fruit. The most common variety, made with sour cherries, is called kriek. Others include framboise (raspberry), cassis (blackcurrant), and pêche (peach). The fruit adds flavor and sweetness. which, like young beer in gueuzes, balances the harsh overtones of pure lambic. The best fruited lambics are not sweetened with sugar, so it's probably best to avoid "Supermarket Lambics" like Lindemans and Timmermans and seek out traditional versions instead.
Try these: Cantillon Fou' Foune, Hanssens Oude Kriek, Drie Fonteinen Hommage
Faro (pronounced just like the grain) is an obscure style of young lambic sweetened with Belgian candi sugar (a type of caramelized brewer's sugar commonly used to make Belgian Dubbels and Tripels). It's typically low in alcohol and much more quaffable than other lambic styles. Some faro is blended with bière de mars, an even more obscure brew made from a second running of the original lambic grain.
Try these: Lindemans Faro, De Cam Oude Faro, Timmermans Tradition Faro Lambic
Perhaps the most common sour beer in the States is Flanders red, a gateway sour ale sold as Rodenbach Classic in bodegas and supermarkets pretty much everywhere. The style originated in the West Flanders region and is a blend of aged and young beer. Flanders red is made with reddish-brown malts and lacto-fermented in oak vessels for up to two or three years. To cut its tartness, young, sweeter beer is blended in, which boosts the finished beer's palatability and complexity. Flanders reds tend to be funky and bracingly tart with fruity esters in their aroma and red wine-like tannins.
Try these: Rodenbach Grand Cru, Bockor Cuvée Des Jacobins Rouge, Duchesse De Bourgogne
Another blended sour ale from the Flanders region is called Oud Bruin ("Old Brown"), or Flanders brown. Though it's often considered synonymous with Flanders red, the styles are completely distinct. (For one, Oud Bruin originated in East, not West, Flanders; this matters to the Flemings.)
While Flanders red is funky and barnyardy, oud bruin is generally more malty and somewhat sweeter with notes of ripe plum and raisins and considerably lower tartness. Like Flanders red, the souring bacteria was traditionally inherited from the tall oak foudres where the beer aged. But many modern versions are now fermented in stainless steel with the addition of pitched yeast and bacteria cultures.
Try these: Liefmans Goudenband, Petrus Oud Bruin, Verzet Oud Bruin
One of the many prominent styles of German sour beers is Berliner Weisse—a slightly tart, extremely thirst quenching cloudy wheat ale native to Berlin. It undergoes a quick fermentation with no supplemental aging, resulting in a low-ABV, high carbonation beer. It's traditionally served in a shallow, bowl-like glass with a squirt of fruit or herb schuss.
Its history dates back several centuries to a pre-Pasteur era of unintentionally soured ale. The style's signature tart kick comes from a bacteria called lactobacillus which, over the centuries, has been introduced to the beer by several different methods. The original delivery was probably through the wheat itself, as it's naturally coated in lactobacillus. Letting a mash (grain plus hot water) sit at warm temperatures for several hours—a process called sour mashing—coaxes the lactobacillus into action, adding tartness and lemon-like acidity to the finished beer. More modern techniques include pitching a lactobacillus culture directly into the beer or even adding straight lactic acid. (In the States, another technique called kettle souring is often used; see below.)
Though once produced en masse by breweries throughout Berlin, the style today is relatively obsolete in its namesake city. Several historic examples survive but now its biggest champions are outside of Germany, particularly in America and other parts of Europe.
Try these: Professor Fritz Briem 1809 Berliner Weisse, Bayerischer Bahnhof Berliner Style Weisse, Schultheiss Berliner Weisse
A recently revived and now somewhat prominent German sour ale is called Gose, a style once synonymous with the city of Leipzig. Like Berliner Weisse, Gose is a slightly tart and highly refreshing thirst quencher made with a high proportion of wheat. Its signature dryness comes from the addition of salt and coriander, knocking it squarely out of the realm of Germany's beer purity law, the Reinheitsgebot.
Gose dates back before the Reinheitsgebot was enacted (the reason it gets a pass) to the town of Goslar where the tiny Gose river flows. By the early nineteenth century it was extremely popular in nearby Leipzig but had all but disappeared by World War II. Only in the last couple of decades has Gose production reappeared, first in Leipzig and then in Goslar. As for the combination of salt and coriander, some say the beer's original water source, the Gose river, is slightly salty. The coriander? That's anyone's guess, though it complements the lemony acidity of lactobacillus quite well.
Try these: Bayerischer Bahnhof Original Leipziger Gose, Döllnitzer Ritterguts Gose, Brauhaus Goslar Helle Gose
German Smoked Sour Ale
Tart, lightly smoked sour ales were once commonly consumed throughout Germany, though most are no longer made. The use of smoked wheat likely derives from ancient, uneven malting techniques, which scorched some grains and left others practically raw. This added a smoky flavor to the beer that fell out of fashion with the advent of modern, uniform malting technology. Today a young German brewer named Sebastian Sauer is reviving many of these forgotten styles under his Freigeist Bierkultur and The Monarchy labels.
Try these: Freigeist Abraxxxas, Professor Fritz Briem Grodziskie, The Monarchy Grätzer
American Spontaneous Ale
American spontaneous ales are analogs to Belgian lambics; the style is built on traditional lambic production techniques and blending methods. The main difference is geographical—which, considering lambic's presumptive reflection of Belgian terroir, is crucial. American-made spontaneous ales are almost never labeled "lambic" or "gueuze"; to do so would be heresy.
Like gueuzes and fruited lambics, they're blended and cut with younger beer and fruit to balance acidity and intensity. They can be some of the most complex and nuanced beers in the world—just don't call them lambics.
Try these: New Glarus R&D Vintage 2015, Allagash Coolship Red, De Garde The Broken Truck
Mixed Fermentation Ale
The main distinction between American spontaneous ales and mixed fermentation ales is that the latter contain some form of pitched yeast strains and/or bacteria culture (meaning the brewer intentionally adds certain strains of yeast and bacteria) and are based on Belgian saisons rather than traditional lambics.
Though processes vary from brewery to brewery, the common thread is a base beer fermented over a prolonged period of time with several different yeasts, then aged in oak barrels or foeders for many months. Often a "house culture" containing brettanomyces, lactobacillus, and pediococcus is added to the beer after primary fermentation, creating depth and complexity. The beers are then bottle-conditioned with yet another dose of yeast.
Note that, strictly speaking, some mixed fermentation ales aren't sour at all—a beer inoculated with only saccharomyces and brettanomyces, for instance, will have some dry, funky notes but none of the tartness that results from lacto- or pedio-aided fermentation.
Try these: Holy Mountain Misère au Borinage, Sante Adairius West Ashley, Side Project Fuzzy
American Goses are amplified versions loosely based around an historic style. For instance, many American Goses incorporate far more salt than traditional ones, while others have a pronounced hop presence, something you'd never find in Germany. Some breweries add in fruit like lime and blood orange or herbs like basil and mint. That doesn't necessarily make any of these bad beers; they're just a far cry from the historic ales of Leipzig.
Try these: Stillwater Gose Gone Wild, De Garde Hose, Off Color Troublesome
American-Style Berliner Weisse
The same can be said for American-style Berliner Weisse; a historic style adulterated and transmuted into a form that would be unrecognizable to a nineteenth-century time-traveling German. One particularly distinct and delightful style is called the Florida Weisse, a regional specialty of the Sunshine State that incorporates some type of tropical fruit right into the finished beer.
Many American Goses and Berliner Weisses are made via a technique called kettle souring. This method involves pitching lactobacillus right into the boil kettle and keeping it at a constant warm temperature at least overnight and sometimes for several days. The lactobacillus acidifies the wort, causing the pH to drop to a predictable level. The acidified wort is then boiled off to kill the bacteria and either pitched with a clean yeast strain or blended with another wort to create the right amount of tartness.
Try these: J. Wakefield Dragon Fruit Passion Fruit, The Bruery Hottenroth, Creature Comforts Athena
Somewhere in between (or just askew of) the American-style Goses and Berliner Weisses is a hybrid form of sour ale amped up with hops. Dry-hopped sours are usually kettle-soured, but some are produced from sour mash or mixed fermentation. They're dry-hopped, like IPAs, but usually have very little bitterness. Instead the hops add huge aromas of tropical and citrus fruit that compliments, rather than clashes with, the beer's tartness.
Try these: Grimm Kinetic Cloud, Evil Twin Sour Bikini, Prairie Funky Gold Series