Q: Recently we have seen a rise in finished beer pH, from 4.4 up to 4.7.This rise concerns me for stability and safety reasons. What are the major contributors to this rise in pH? We are adding 100ppm of Calcium salts to both our mash and kettle boil, and do not brew with any acidified malt. The pH of our city water fluctuates between 6-8, and we have seen a rise in hardness from 120ppm to 150ppm, as well as a rise in Alkalinity from 120 to 160ppm (total as CaCO3).
A: pH in beer is usually pretty reliable unless there is some change in the raw materials or process. Beer is an incredible pH buffer, changes in pH are difficult to achieve without a lot of inputs. The change in water alkalinity is interesting but I wonder if there is not something else going on. The challenge with any kind of change is to try to figure out where the change occurred. Some things to check on:
- Did the pH of your mash, run-offs or knock out wort change (rise)?
- Did you change malt varieties or suppliers?
- Have you checked sodium content to see if you have picked up a caustic contamination?
- Are you seeing the pH rise at any particular part of the process?
I would be particularly concerned about a slight caustic contamination, make sure to check the process at each step for out of spec variations and to look at possible contamination routes, i.e. dead legs, incomplete rinsing, bad check valves, etc.