What makes beer tart?

Answered by Phillip Nicastro

When it comes to sour beers, what makes them tart is the use of wild bacteria and yeast during the brewing process. Unlike other beers that rely on specific strains of yeast for fermentation, sour beers embrace the world of microbes to create their unique flavors.

Two bacteria that are commonly used in sour beer production are Lactobacillus and Pediococcus. These bacteria are known for their ability to convert sugars into lactic acid, which contributes to the tartness in the beer. Lactobacillus, in particular, is often used in sour beers because it produces a clean, crisp acidity.

Another microorganism that plays a significant role in creating tartness is Brettanomyces, often referred to as “Brett” for short. Brettanomyces is a wild yeast that is commonly associated with farmhouse-style ales and lambic beers. It is known for producing complex flavors, including acidity, in beer. When used in sour beers, Brettanomyces adds a distinct sourness that complements the lactic acid produced by the bacteria.

The use of these wild bacteria and yeast strains introduces an element of unpredictability into the brewing process. Unlike traditional brewing, where specific yeast strains are carefully selected to achieve desired flavors, sour beer production relies on the natural fermentation capabilities of these microbes. This variability can lead to a wide range of flavors and aromas in sour beers, making each batch a unique experience.

The brewing process for sour beers often involves a combination of traditional brewing techniques and extended aging periods. After the initial fermentation using traditional brewing yeast, the beer is exposed to the bacteria and yeast that will create the sour flavors. This can happen through a process called “open fermentation,” where the beer is exposed to the air, allowing wild microbes to inoculate the brew. Alternatively, brewers may introduce the bacteria and yeast intentionally by adding them to the beer.

Once the wild bacteria and yeast are introduced, the beer is typically aged for an extended period of time, often in oak barrels or stainless steel tanks. This extended aging allows the bacteria and yeast to work their magic, creating the desired tartness and complexity in the beer. The length of the aging process can vary depending on the desired flavor profile and the specific strains of bacteria and yeast used.

It’s worth noting that not all sour beers are intensely tart. Some sour beers, such as Berliner Weisse or Gose, are known for their lighter, more refreshing acidity. These beers often undergo a shorter fermentation and aging process, resulting in a milder tartness compared to other sour beer styles like Lambic or Flanders Red Ale.

To sum it up, what makes beer tart is the use of wild bacteria and yeast, particularly Lactobacillus, Pediococcus, and Brettanomyces. These microbes convert sugars into lactic acid and other compounds that contribute to the tart, crisp flavors found in sour beers. The combination of these wild microbes, extended aging, and unique brewing techniques results in the wide range of sour beer styles and flavors that beer enthusiasts enjoy.