pH Measurement Temperature
A recent set of articles on 'Measure pH Correctly' in the October and December 2017 issues of Brew Your Own (BYO) magazine raised quite a firestorm on the internet and in the magazine. Most of the controversy centered on the issue of pH and its measurement temperature. A sidebar in the article said that the typically recommended pH range of 5.2 to 5.5 refers to mashing temperature measurement, not room-temperature. You’ll learn here, why the recommendations in those articles are incorrect and why you should ALWAYS CHECK MASHING PH USING A ROOM-TEMPERATURE WORT SAMPLE.
The first error in the article has to do with if current brewing research used mashing or room temperature measurements. Unfortunately, there is no consensus that researchers based their pH recommendations on mashing- or room-temperature measurement. Dozens of brewing studies have assessed a variety of brewing optima and effects, but not all researchers state what their wort temperature was during pH measurement. There is precedence regarding how brewers should check pH since the ASBC Method of Analysis for determination of wort pH directs that the wort sample be brought to room-temperature. In addition, placing a pH probe in and out of hot wort WILL shorten its life. All of these factors point to ROOM-TEMPERATURE MEASUREMENT. So, measurement temperature is long settled. Now let’s talk about what the proper pH range is.
During the production of Palmer and Kaminski’s Water book, John Palmer sent a worried message to AJ DeLange and me that questioned if the typical brewing pH range referred to room- or mash-temperature measurement. AJ’s response follows: “If that range is supposed to be the optimum at mash temperature and mash pH is supposed to be 0.3 less than room temperature, the proper range at room temperature would be 5.5 - 5.9 and we would be hard pressed to explain the large number of brewers who noted great improvement in their beers when they got mash pH down to the 5.4-5.6 range. Certainly that has been my experience.” So, all of us agreed that our recommended range of 5.2 to 5.6 is based on ROOM-TEMPERATURE MEASUREMENT.
To say that there is an "optimum" pH or temperature that we should mash at, is a fool's errand. There are a lot of "optimums" at work in the mash and its the brewer's prerogative to decide what those values should be for the brew at hand. Keying your “pH” optimum to mashing temperature is just chasing your tail. Find the room-temperature mashing pH that works for you.
The bottom line is that brewers should measure mashing pH with a room-temperature measurement and key that information to how the beer turns out. Successive brews at slightly differing pH will help define what the brewer really wants to target.
On a melancholy note, the brewer that posed the original question that generated this controversy in the October BYO article was one of my homebrew club members, Dave Allen. Unfortunately, Dave passed away about a month ago and that loss weighs heavily on many of us.
RIP, Dave.
