What is the typical duration needed for kettle souring to reach a pH of 3.5?

Kettle souring is a process that involves the addition of lactic acid bacteria to a wort, which allows it to sour before the boiling stage. The goal of kettle souring is typically to achieve a specific pH level that indicates the desired level of acidity in the finished beer.

The typical duration for kettle souring to reach a pH of around 3.5 usually falls within the range of 18 to 36 hours. During this time, lactic acid bacteria such as Lactobacillus convert sugars in the wort into lactic acid, gradually lowering the pH. Factors like temperature, the concentration of bacteria, and wort composition can influence the souring time; however, the 18-36 hour range is a common timeframe recognized by brewers.

This timeframe allows sufficient fermentation for the desired acidity without extending the process too long, which could lead to undesirable sourness or off-flavors. Thus, the chosen answer aligns well with practical brewing experience regarding the kettle souring process.