The content of this page was updated on 8/19/2012.
All-grain brewers: did you know that pH is just as important as temperature for mashing and sparging? It's true! You already know that alpha amylase and beta amylase, the malt enzymes responsible for converting starches into sugars, work best at temperatures between 149 and 158 degf. They also work best when the pH is between about 5.2 and 5.5*. If your mash pH is too far out of that range, your runoff gravity will suffer. If the pH of your grainbed is too high during sparging, you could extract excessive tannins.
Surprisingly, a lot of craft brewers don't pay much attention to pH. I'd wager the reasons are twofold:
-The underlying water chemistry is extremely complicated.
-Mash pH tends to work itself out, as long as the mash water is low in carbonates.
Unfortunately, Madison's municipal water is high in carbonates. Carbonates raise mash and sparge pHs, so brewers 'round these parts should strive to get rid of them. In the next few weeks, I hope to show you a few simple ways to do just that. Afterward, I'll outline some calculations that will either bore you to death or help you fine-tune your water treatments for specific recipes**. The next article in this series is here.
*When measured at room temperature, which you should always assume unless I specify otherwise.
**I'm not a water chemistry expert like A.J. deLange, who probably has nightmares about people like me giving advice on the subject. My calculations work well in my home brewery, but accounting for all of the chemical reactions and how they're affected by things like pH, time, temperature, molecular concentrations and the partial pressure of atmospheric CO2 (seriously) is way over my head. Throughout this series of posts, you should take my geekery with a grain of salt.