Getting bored with IPAs and pilsner? You might want to delve into the funky, flavorful world of sour beers.
Sour beer hearkens back to ancient brewing styles, which relied on wild yeast and bacteria to help ferment the beverage.
Before pure commercial yeast cultures were available to brewers, all beers were a little sour. During the brewing process, wild yeast and bacteria were purposely introduced to the wort (the liquid extracted after the mashing process) by cooling it in a large vat that was exposed to the wild yeast in the air, or by aging the beer in wooden barrels which were porous enough for wild yeast and bacteria to make their way into the mixture and spur fermentation. The combination of bacteria and wild yeast created a sour flavor that is still characteristic of modern sour beers.
These days, brewers typically rely on three types of bacteria to sour their beers: Lactobacillus, Brettanomyces, and Pediococcus, which are used in conjunction with wild or commercial yeast. Some sour beers get their flavor from fruit that’s added as the beer ages, which causes a second round of fermentation. But any method of brewing sour beer is unpredictable, and different combinations of wild yeast and bacteria create very different styles of beer throughout the world.
American Wild Ale
Most American wild ales are brewed using a combination of wild yeast, Saccharomyces cerevisae (a type of yeast often used in craft brewing), and brettanomyces. The style of American wild ale varies greatly depending on the balance of malt and hops, how long the beer is aged, what it’s aged in, and the type of wild yeast used. The flavor profile can include sour, funky, barnyard and earthy notes. Unlike European sour beers, which often must conform to certain specifications in order to be classified as a sour, there isn’t much that is set in stone when it comes to American wild ales, other than the use of wild yeast.
Berliner weisse (Berlin white) is a low ABV, cloudy white beer. Berliner weisse is fermented with a combination of yeast and lactic acid bacteria, which gives the beer a unique flavor and mouthfeel. The tart brew is often flavored with raspberry or woodruff-flavored syrup, to counteract its sourness, and it is usually enjoyed in the summer months. Berliner weisse is an appellation d’origine contrôllée, meaning that ales bearing this name must be brewed in Berlin.
Flanders Red Ale
Flanders red ale is a style most commonly brewed in West Flanders, Belgium. Often considered to be the most wine-like beer (sometimes even called “the Burgundy of Belgium”) due to its tannins and lack of hoppy bitterness, Flanders red ale is usually aged in oak barrels for up to three years. Naturally occurring microorganisms, bacteria, and yeast in the barrel give the ale a moderately sour flavor. Flanders red ale has a fruity flavor profile, with plum, black cherries, raspberries and even dried fruit flavors present in many beers made in this style. Those flavors, along with the tannins present from barrel-aging and the mouthfeel that results from fermentation with lactic acid, contribute to the wine-like characteristics of Flanders red ale.
Gose, a sour beer brewed with coriander and sea salt, is a traditional German style that nearly disappeared after the last brewery making the beer closed in 1945. Luckily, a former employee of the brewery decided to continue making it, then passed the recipe to his stepson who continued to make it until his death. There was another gap in availability after his death in 1966, until a brewer resurrected the style in the 1980s. Since the late 80s it has been brewed continuously in Germany. Gose was traditionally allowed to spontaneously ferment, though modern brewers use commercial strains of top-fermenting yeast and lactic acid bacteria. Today, there are more than 100 versions of Gose being brewed in the USA, and aside from the sour, salty base flavoring, there are many interpretations of the style.
Lambic beer, originally from an area outside of Brussels, is a spontaneously fermented brew dating back to the 13th century. More than 80 natural yeasts ferment lambic, giving it a unique sour flavor reminiscent of sherry and cider. Lambic is brewed in the winter and is aged for at least one year. While it can be drunk on its own, it is usually used as a base for sweet and sour fruit beers, like Kriek (sour cherry) and Framboise (raspberry). Fruit is either added to the young lambic and allowed to ferment, or fruit juice is blended with the young lambic and bottled, where the beer undergoes a secondary fermentation. Gueuze is another popular style, which is made by blending 1-, 2-, and 3-year-old lambics. The resulting blend is bottled and allowed to undergo a second fermentation.
Oud bruin (Old Brown) is another Flemish sour. This style undergoes secondary fermentation and is aged for at least a year, which encourages its sour flavor to develop. Unlike Flanders red ale, oud bruin is aged in steel casks and fermented with cultured yeast and bacteria. The beer has dark fruit notes, like prune, plum, and black cherry, as well as caramel, toffee, and orange hints contributed by the malt used in brewing. Oud bruins that have been aged significantly can start to take on sherry-like characteristics.
What was once a rare European style of beer has become increasingly popular, with hundreds of varieties of sour ale being brewed in the USA alone. If you’re interested in trying the originals or experimenting with something new, head to your local tap room or specialty beer retailer and ask for their recommendations.