Those of you that are new to brewing probably have a lot of questions about the process, so we’re going to clue you in on a step that we’re somewhat familiar with: testing and adjusting mash pH.

What is mash? Mash is a step in the brewing process involving hot water steeping which hydrates the barley, activates the malt enzymes, and converts the grain starches into fermentable sugars. This process is called conversion, and it occurs in water under certain conditions of volume, temperature, pH and time.

Ideal Mash pH

Conversion works best when the mash is within a pH range of 5.0-5.5. A pH of 5.4 is considered ideal for most applications, and is a good benchmark for new brewers.

Sugar conversion and fermentability are affected by the pH of mash. Malt enzymes α- and β-amylase require a slightly acidic pH to function properly.

Uncontrolled mash pH can result in flavors that are a bit off, so your taste buds will thank you for doing this test.

Testing Mash pH

Testing the pH of mash is a crucial part of the brewing process. Always measure mash pH at the same stage in the mashing process: after you have mixed your water and grains.

Our Beer pH Test Strip is a great option for beginners testing mash pH.

  • Just dip the colored pad into the mash for 1-2 seconds.
  • Remove the strip and compare it to the color chart within 10-15 seconds for a pH reading.
  • Don’t let the pad dry before comparing it to the color chart.

It doesn’t get much easier than that!

The pH test strips will read beyond the values shown on the color chart, so if you’re getting a reading that’s darker than 6.2, it means your pH is even higher. You won’t be able to determine an actual pH value, but that doesn’t really matter because you’re well above the optimal pH of mash.

If your mash contains a lot of dark malts, their color can stain the strip when you’re trying to get a reading. Dark malts are probably better tested with an inexpensive pH tester.

It’s also important to understand that temperature has an effect on pH test strips. Measuring the pH of the mash at a temperature of 150°F won’t work. Let it cool to room temperature before testing the pH, and then correct for the difference.

Page 202 of the book, New Brewing Lager Beer states that it’s important to “be aware that density and pH readings may vary with temperature, so the hotter the mash… the lower the density and pH appear to be.”

Page 75 of the book, Standards of Brewing reminds us that “pH changes with temperature, so [mash] at 149°F will have a pH about .35 lower than that measured at 68°F.”

Use the correction factor of .35 when measuring mash or wort.

Adjusting Mash pH

If you need to lower the pH of your mash, you need to increase the acidity. Use one of the following:

  • Gypsum
  • Lactic Acid
  • Calcium chloride

If your mash is too acidic, you need to increase the pH using one of the following:

  • Calcium carbonate
  • Sodium bicarbonate (baking soda)

Alternatively, Five Star 5.2 pH Stabilizer is a product that adjusts the pH of the mash either way to stabilize it at 5.2.

When adding these ingredients, don’t add more than a teaspoon at a time, especially in small batches. Continue to take readings and adjust until you are within the optimal pH range.

Pretty simple, right? Well it can definitely get more complicated, but for beginners, these are the basics you need to know to brew your first few batches.