All About Sour Beer: 8 Types of Sour Beer

Sour beer is a variety of beer made with wild yeasts that produce a sour or tart flavor. The yeast strains for brewing sour beers or sour ales are often unpredictable. Sours are often location-specific, as the particular varieties of local wild yeasts play a role in their flavor. The tart notes of sour beer can be dominant, but there are also familiar beer flavors of malts and hops. This variety of beer is often barrel-aged.

Traditional brewing methods go back into antiquity, and many of the earliest forms of fermentation probably resulted in some degree of sour flavor. The earliest beer with deliberate sourness came from Belgium. Lambics and Flanders red ales are early Belgian varieties of sour beer that have been brewed continuously for centuries. Today, with the popularity of sours among craft beer aficionados, microbreweries worldwide are experimenting with this challenging but rewarding type of beer.

It goes without saying that sourness is central to the flavor profile of sour beer, ranging from a mild, citrusy tang to a mouth-puckering hit of acidity. Sour beers often feature intense fruit flavors. Wild-fermented varieties have surprisingly complex flavor profiles, with juicy sweetness, floral notes, earthy undertones, and bracing funkiness.

There are several different varieties of sour beer, with brewers continually inventing new ones. Below are some of the most common types of sour beer:

1. 1. Berliner Weisse: This German sour variety is made with wheat as its principal grain, and is traditionally served with fruit syrup to balance its tartness. This beer has a low ABV of about three to four percent.
2. 2. Flanders red ale: This is a traditional Flemish variety of aged sour. Known for its deep red color and its bracing tartness, Flanders red ale is enjoyed in the Flanders region and beyond.
3. 3. Oud bruin: Oud bruin, also known as Flemish brown, is a Flemish-style sour beer from the Flemish region of Belgium. This variety is not aged in oak barrels.
4. 4. Gose: This ancient German variety traditionally includes salt and coriander as flavorings and has a light, refreshing tartness.
5. 5. American wild ale: This broad category of sours refers to beers brewed in the United States using wild fermentation. Wild yeasts, which are not commercial domesticated yeasts, are responsible for the fermentation process.
6. 6. Lambic: This sour beer from the Pajottenland region of Belgium is spontaneously fermented and aged in oak barrels. Spontaneous fermentation means the wort is left exposed to the open air for a period to colonize with native species of wild yeast.
7. 7. Framboise: This Belgian lambic beer is brewed with raspberries, which impart flavor and color to the brew.
8. 8. Gueuze: This subtype of lambic involves blending young and old varieties of lambic, aging them together, and adding sweet fruits like cherries to balance the sharp tartness of the brew.

The unpredictability of some brewing methods—often using wild yeast strains—means that sour beer brewers must commit to a degree of trial and error. This experimentation can yield exceptional, elusive results. Many craft breweries will offer sour beers seasonally with changing flavor profiles from year to year, and certain vintages are aged like wines.

Like all brewing, sour beer requires care and attention to detail. Many home brewers gain experience before tackling sours; the addition of different yeast, bacteria, and fungal strains at different stages means there’s a slim margin of error. The process is as follows:

1. 1. Make the mash. Brewing sour beer begins like plenty of other beers—malted grain is mashed, which is the process of immersing in water and heating for a specific amount of time, depending on the recipe.
2. 2. Add the hops. If hops are part of the recipe, add them during the mash process. Most sour beer recipes call for very little hops since too much will inhibit the souring bacterial growth later on.
3. 3. Cool the wort. Allow the dissolved sugar and water mixture from the mash, known as the wort, to cool. Then, transfer the wort to the secondary fermentation vessel. This container is typically a glass jug called a carboy.
4. 4. Add the yeast. Next, add the brewer’s yeast or a combination of traditional commercial yeast and specialized bacteria. The bacteria is often lactobacillus, which produces sour-tasting lactic acid to create the first step of the souring process.
5. 5. Begin fermentation. Fermentation begins shortly and will remain active for a period, often ranging from a few weeks to several months. In some recipes, this is where the other fermenting agents—Lactobacillus, Brettanomyces, and Pediococcus—are either directly added, or allowed to settle on open fermentation vessels.
6. 6. Start the aging process. Once the beer reaches desired sourness and alcohol content, you can bottle it and place it in a cellar or transfer the beer to oak casks, where it can undergo a prolonged aging process that can last for years.

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