This script is from the second season of Beer Notes, which you can listen to at beernotes.org.
Since beer was first fermented in 7000 BC, all beers were sour, or at least they turned sour with age. Sours get their sourness from fermenting agents: acid producing bacterias, wild yeasts, or any type of conventional or unconventional yeasts, according to CraftBeer.com. The souring of beer is hard to produce and harder to control.
The discovery of single-strain yeasts and pasteurization and sterilization processes allowed brewers to create consistent ales and lagers and eventually even IPAs that wouldn’t sour and these beers became the dominant styles in the United States. It wasn’t until the 1970s that Belgian sour beers made their way to the United States, thanks to the importation of lambic, a spontaneously fermented sour ale that dates back to the Roman empire, and gueuze, which is made of blended, aged lambics.
As time went on, forward-thinking brewers like Rob Tod of Allagash and Sam Calagione of Dogfish Head made trips to Belgium to learn the secrets of gueze and the processes used to brew other Belgian sours. They brought back sour-brewing trade secrets and further solidified the place of the sour in the landscape of American beer.
The term “Sours” can cover numerous styles of beer with different alcohol contents and colors. The Beer Judge Certification Program (BJCP) now recognizes 10 different styles of beer that are all sour and more will surely be added as brewers continue to push the envelope of what they can do. For Beer Notes, this is Ann McGinnis Hillyer.