The temperamental enzymes which release the sugars from the malt in the mashing process need a slightly acidic environment to do their job well. This requires the brewer to keep a diligent eye on the mash’s pH. There are many ways to test the pH of the mash. The easiest is to buy pH test strips from your local homebrew store. This is just as simple as taking a sample of the liquid, dip the strip which will change color based on the liquid’s pH, and compare the color to a chart, which will show the pH. There are various other meters and chemistry kits used to test pH, but unless you are doing very advanced homebrewing or have a questionable water source, the pH test strips will work fine.
There are a few things to keep in mind when thinking about mash pH:
- Different styles of beer have different mashing pH. This can get pretty advanced, but it is important to know that some beers require a lower (more acidic) mash pH than others. The bottom line is to know where you want the mash pH.
- Dark malt is more acidic that pale malt. This is important to know when testing the water prior to adding the grist (grains). The pH of the water should test somewhere between 5.8 and 6.5 so the mash pH settles into that sweet spot after the grain is added. The pre-grain water should test closer to 6.5 for darker grains and closer to 5.8 for paler grains.
- You will need to adjust the pH to keep it in the proper range. There will be more on this later, but you will need to add gypsum when the pH is too high (basic) and calcium when it is too low. Both can be purchased from your local homebrew shop. This is a bit of a painful process and requires the addition of small amounts of either the calcium or gypsum, mixing, retesting, and repeating until the pH is right.
- In the mashing process, when the warm water is mixed with the grain, it will cause the pH of the liquid to go down (become more acidic). About five minutes after the water and the mash are mixed together the mash liquid should have a pH somewhere between 5.0 and 5.5. When testing the pH at this point, ensure the sample of liquid taken from the mash is allowed to cool to room temperature before testing, as warmer temperatures can cause a bad pH reading. Fancy scientific instruments have automatic temperature control but that is not an option if you are using test strips. Be sure to follow the directions of your chosen pH testing kit.
I’m sure there are lots of home brewers out there whose blood pressure is going to go dangerously high when I say this, but if you are brewing beer from malt extract, pH is not that big of a deal. pH is a much bigger concern for more advanced brewers, primarily in the mashing process. I am also assuming your water source is suitable for drinking and you are not drawing your water from your local canal or storm drain. Keep in mind that when you move from extract to all-grain brewing, pH becomes a big deal. A good way to wreck a batch of beer is to use hope as a course of action in dealing with pH. Make sure you have a good idea of the pH you want for the style of beer you are making and you have the right stuff to test the water.