When diving into the world of sour beers, it can be a little overwhelming to know where to start. One critical step is knowing how to distinguish the difference between what is a traditional sour beer and a kettle sour. While they may sound similar, the two techniques couldn’t be further apart and produce beers that are wildly different in taste.
First let’s tackle the traditional sour beer. In general, a sour beer is a beer that is brewed through your average brewing process and then transferred into oak barrels for an aging process that can take anywhere from a few months, to a few years. It’s during this aging process that the beer is exposed to the yeast (wild or deliberate) and that yeast imbues the beer with the sour effect in the final product. Often brewers will go the added step of incorporating fruits into the aging process as well, adding some extra complexity to the beer.
The key ingredient in traditional sour beers is time. You cannot rush the aging process and as the yeast works its way into the beer there will be substantial changing to the final product between time periods. A six month aged sour will be vastly different than a year, and so on. The time needed, and careful consideration of the beer inside is why traditional sour beers tend to be on the more expensive side. You’re paying for the time and effort put in to crafting these brews.
To identify beers in this style look for categories like “Oud Bruin” or “Lambic”, or look for identifiers that point out the beer was barrel aged.
Kettle sours on the other hand can be rapidly produced, with minimal aging. This might be why many breweries offer a kettle soured beer rather than a barrel aged variety, it is simply easier and quicker to produce.
“Kettle” refers to the brew kettle, which means that the beer is soured in the steel mash tun and fermented in a similar steel tank. This method produces a beer that is tart and tangy, think puckering sour over depth of flavour sour. Brewers achieve the sour profile by adding in a specific yeast called “lactobascillus”, a probiotic bacteria that converts sugars into lactic acid. You’ve likely encountered this bacteria before, it’s the same type of bacteria culture that creates the sour notes in foods like unsweetened yogurt.
Kettle sour styles include beers like Berliner Weisse and Gose, with the primary result again being a very tart flavour profile.
While the argument over which method produces a better beer can be contentious, the reality is that each produces a beer that simply can’t compare to the other. Traditional sours are complex and rich, while kettle sours are tart and refreshing. What you prefer is up to you.