Mash pH
The mash pH for sour beers, like other styles, is generally kept within the range of 5.2 to 5.6, a crucial parameter for ensuring optimal enzymatic activity during sugar conversion. While this standard mash pH supports the brewing foundation, the distinctive acidity of sour beers emerges later in the process, as specific techniques and microorganisms are introduced to develop their signature tang and complexity.
Wort Acidification
For sour beers, acidity can be introduced at various stages of the brewing process using different methods. Each technique offers its own advantages and influences the final taste profile. One common approach is kettle souring, where lactic acid bacteria (Lactobacillus) are introduced to the wort before boiling. This method produces lactic acid, dropping the pH to a range of 3.0 to 3.5, creating a tangy base before the wort is boiled and sterilised. Alternatively, mixed fermentation employs a combination of yeast, lactic acid bacteria, and wild microbes like Brettanomyces, allowing the acidity to develop naturally over time and contributing complex flavours. Lastly, acid additions involve directly incorporating food-grade acids such as lactic or phosphoric acid to quickly lower the pH. While effective, this method may lack the depth and complexity of flavours found in naturally soured beers.Â
Fermentation
In sour beer fermentation, yeast harmoniously coexists with lactic acid bacteria (LAB) in an acidic environment. This synergy not only stabilises the pH but also drives the production of alcohol and a variety of organic acids. These acids enrich the beer’s profile, contributing to its depth, complexity, and distinctive character.
pH and Flavour in Sour Beers
The sharp, tangy taste of sour beers is a direct result of their low pH, with lower pH levels intensifying the perceived sourness. However, pH does more than just drive tartness—it also plays a critical role in how other flavours, such as fruit or spices, are experienced. When properly controlled, the pH ensures that the sourness complements rather than overpowers the beer, creating a harmonious and well-rounded flavour profile.
Challenges in pH Management
Sour beers require precise pH management, as mishandling can lead to off-flavours, such as an overwhelming vinegar-like taste caused by excessive acetic acid production. On the positive side, the lower pH acts as a safeguard against spoilage by inhibiting unwanted bacteria. However, maintaining strict sanitation throughout the brewing process is essential to prevent contamination and ensure the integrity of the final product.
