A sour beer is one that has been deliberately brewed to achieve high levels of acidity. This elevated acidity delivers a predominantly sour flavor to the beer as opposed to the bitter or sweet flavors found in standard ales and lagers.

The souring process relies on fermentation by acid-producing bacteria such as lactobacillus, pediococcus or acetobactor that feed on sugars in the beer and excrete organic acids as a metabolic by-product. While these bacteria are considered “beer spoilage organisms” in most common beers styles such as IPAs, stouts and lagers, sour beer producers purposefully use them achieve a desired level of sourness.

There many ways to make sour beer, but the most common methods involve brewing the “wort” (unfermented beer), then introducing acid-producing bacteria either naturally by exposing wort to the open air or by adding a bacterial culture. The fermenting beer is then held in stainless steel tanks or oak barrels for several months (or even years!) while the slow, steady bacterial fermentation takes place. During this time, the brewer may choose to add other ingredients such as fruits or spices to achieve a desired flavor. Once the brewer deems the beer ready, a variety of barrels are selected and blended together into a single tank. The finished blend is then packaged into bottles and kegs for consumption.

Here at Cascade Brewing, we apply the term Northwest Sour Ale to our beers as a way of defining our product outside the parameters of the common preset categories of beer that may otherwise limit creativity and innovation. These northwest sour ales are barrel-aged and feature a clean, lactic acid profile produced by our own house culture of lactobacillus bacteria. Another major component of our northwest sour ale includes our use of fresh ingredients grown exclusively in the Pacific Northwest, such as cherries, apricots, berries and grapes. In part, however, the term northwest sour ale will always maintain a certain lack of definition that allows us the creative space to constantly approach our beers in new ways.

The process of making quality sour beer isn’t cheap! While most styles of ale can be made in less than a month using basic brewing equipment, sour beer can take significantly longer to produce – up to three years in some cases – and requires huge investment in specialty equipment. Storage of sour beer requires large warehouse spaces in which to house the beer during the aging process. Additional costs such as barrels, racks, blending tanks, cellar staff, and ingredients all add significant costs to making sour beer that traditional non-sour breweries don’t incur. The tradeoff, however, is that sour beer can achieve a level of uniqueness and complexity that few other beer styles can match. Experiencing the sophisticated flavors and aromas found in sour beer can be a revelation to the uninitiated. In fact, sour ales are often considered the finest beers produced in the world.

Surprisingly, no, sour beers have been around since humans began brewing beer thousands of years ago. In fact, it’s likely that most beers in brewing history were, indeed, sour. This is because acid-producing bacteria exist everywhere – in the air, on the ingredients, in fermentation vessels, even on your skin! It is only with the industrial revolution and increased scientific knowledge of sanitation that brewers gained the ability to prevent beer from souring naturally. Since that time, most beers have brewed to be non-sour, however, as craft brewers seek to push the boundaries of creativity, sour beers have made a roaring return to the market.