If you’re a lover of craft beer, it means that you’re adventurous and happy to try something new. You might want to consider sour beers. Sour beers are growing in popularity with both veteran beer drinkers and novices alike. At one time, all beers were sour beers, to some degree. Some people wonder how to brew sour beer? Sour beers are made by intentionally allowing wild yeast strains or bacteria into the brew. History shows that in the more-or-less modern era, the first sour beers were brewed in Germany and Belgium in the sixteenth century as German and Belgian brewers allowed wild yeast to enter the brew. It’s a bit of an unpredictable process that most brewers today avoid.
It is essentially a science, as sour beers take a brewer months to ferment and can take years to mature. Immigrants from Belgium and Germany first brought traditional sour beer to the United States in the late 1800s, but with the emergence and spread of refrigeration and pasteurization, sour beers almost disappeared as lagers grew in popularity. Since the 1970s, however, sours beers and flavors have returned, and they’re now increasingly popular with beer drinkers in the U.S. and around the world.
WHAT ARE LACTO, PEDIO, AND BRETT?
Sour beer is sour due to the addition of living bacteria like lactobacillus (“lacto”) or pediococcus (“pedio”) and a strain of yeast called brettanomyces (“brett”). A beer that would normally take days or weeks to ferment takes months or even years with brett. Brett slowly ferments beer and is responsible for what brewers refer to as “funk.” The phenols in brett create the distinct taste and the aromatic “funk” present in sour beers.
Lacto converts sugars into lactic acids rather than alcohol, lowering the beer’s pH and making it sour. Pedio also produces lactic acid and lowers pH, but many beer lovers will find the sourness or funk of pedio more pronounced or “harsher” than that produced by lacto. Some brewers also add fruit to enhance flavor, spur secondary fermentation, or to add the microbes naturally present on the fruit’s skin.
HOW ELSE ARE SOUR BEERS DIFFERENT?
Yes, it’s beer, but sour beers are different. They do not use conventional brewer’s yeasts and are not brewed in a sterile environment. Many Belgian brewers still encourage wild yeast strains and bacteria to enter into their sour brews by cooling their “wort” (their unfermented beer) outdoors. And while most beers are aged in a barrel or metal tank, sour beers are aged in wooden vessels, allowing the bacteria to remain alive in the beer.
Most sour beers average somewhere between 3 percent and 5 percent alcohol by volume, although some may be as low as 2 percent or as high as 8 or 9 percent. The alcohol content hinges primarily upon the exact style of sour beer and the conditions under which it was brewed. Here is a more detailed guide and look at the different styles and most popular sour beers that beer drinkers are enjoying today:
AMERICAN WILD ALE
Beers brewed in the United States that utilize yeast and bacteria strains – instead of or in addition to standard brewers’ yeasts – fall into the catch-all category of American wild ale. Microflorae are cultured or acquired spontaneously, and the beer may be fermented in a variety of types of brewing vessels. The phrase “American wild ales” simply refers to the use of unusual yeasts, as these brews tend not to have specific parameters or stylistic guidelines.
Berliner Weisse is a sour, tart, fruity, highly effervescent, spritzy, and refreshing ale that holds only a fraction of the market share in Germany but is still quite popular in and around Berlin. These sour beers are usually flavored with fruit syrups to balance their tart flavor. In the late nineteenth century, the great Berliner Weisse was the most popular alcoholic drink in Berlin, with dozens of top Berlin breweries producing it. These are low alcohol content beers made sour by using the lactobacillus bacteria. A typical modern strength for Berliner Weisse is around 2.7 percent alcohol by volume.
FLANDERS RED ALE
Flanders red ale is a style of sour ale brewed in West Flanders, Belgium, since the seventeenth century. Flanders red ales are first fermented with regular brewers’ yeast, then placed into oak barrels to age and mature. The aging period is long, a year or more, and the oak imparts a lactic acid character to the beer. Red malt is used to give the beer its color, and the matured beer is often blended with a younger batch before bottling to balance and round out the character.
Gose (pronounced “go-suh”) is an ancient, sour and saline tasting ale. At least 50 percent of the grain bill is malted wheat. The brew is spiced with coriander and hops and brewed with slightly salted water. Gose is made sour by inoculating the wort with lactic acid before fermentation. Gose was first brewed in the sixteenth century in Goslar, Germany, but it became so popular in Leipzig that local breweries copied the style. By the end of the 1800s, it was considered to be local to Leipzig and there were numerous gose taverns throughout the city.
Lambic beer is spontaneously fermented beer made in the Pajottenland region of Belgium, southwest of Brussels, and in Brussels itself at the Cantillon Brewery. The wort is exposed to the open air during the winter and spring, and it is then placed into barrels to ferment and mature. Most lambics are either blends of several season’s batches, or else they are secondarily fermented with fruits, so that good, pure, unblended lambic is quite rare. The best Lambic sour beers come in several varieties including Gueuze, Mars, Faro, and Kriek.
Oud Bruin (Old Brown), also known as Flanders Brown, is another style of beer from the Flemish region of Belgium. The Dutch name refers to the long aging process, which takes up to a year. The Oud Bruin undergoes a secondary fermentation, which takes several weeks to a month, followed by bottle aging for several more months. Extended aging allows residual yeast and bacteria to develop a sour flavor. Oud Bruins differ from the Flanders red ales in that they are darker and use cultured yeasts.
Today, sour beers have spread far beyond Belgium and Germany – they’re frequently enjoyed and people love them around the world. Sour beers are now brewed across Europe and also at a number of craft beer breweries here in the United States, and they’re rapidly growing in popularity. If you’ve never ventured too far from pale lagers and wheat beers, you won’t have to search far to take the sour beer plunge. You may be surprised by the reward.