Unlike modern brewing, which is done in a sterile environment to guard against the intrusion of wild yeast or bacteria, sour beers require some form of bacteria to get those sour, tart flavors. There are quite a few sour beer styles, and the most common forms of bacteria or wild yeast used to intentionally sour beer are Lactobaciius, Brettanonyces and Pediococcus.
Another way to sour beer is to add fruit during the aging process to start a secondary fermentation. Fruited sours are becoming very popular, and many will use local heirloom fruit from small farms.
Most sour beers start as a normal beer that is then “soured” in some way by adding bacteria. Another way to sour beer is to put the wort (unfermented beer) in a coolship vessel (which is an open-to-the-elements piece of equipment) so that wild yeast or bacteria in the air surrounding the coolship will start the fermentation process. Almost all sour beers are aged in barrels for varying amounts of time, and fruit could also be added to the barrel.
Some sour beer styles that are becoming popular include American wild ale, Berliner weisse, Flanders red ale, Gose, and Lambic. Most of these beers have a long history and are making a comeback in production and popularity. Sour beers are a specialized form of brewing and, when barrel-aging these beers, it can take some patience as it takes time for the beer to mature. If you lake things that are tart and sour, then these beers are for you!
Life’s short, drink craft! Cheers!
Rob McFerren is the owner of Wolf Creek Restaurant & Brewing Co.