All Grain Brewing Lessons: Mash pH

Achieving the perfect mash pH is a crucial step in the beer brewing process that is frequently overlooked by new all grain brewers. Mash pH and water chemistry in general can be a daunting topic to take on. The following article will aid as a learning and reference tool for your next brew day.

What is Mash pH?

Mash pH refers to the measurement of acidity or alkalinity in the mash, which is the mixture of crushed grains and hot water during the start of the all grain brewing process. It is typically measured on a pH scale ranging from 0 to 14, with 7 being neutral, 0 being extremely acidic and 14 being extremely alkaline. For most beer styles, a mash pH between 5.2 and 5.6 is considered ideal.

Why worry about pH?

Enzyme Function: Mash pH plays a key role in enzymatic activity, specifically the conversion of starches into fermentable sugars. Enzymes responsible for this process have an optimal pH range that sits in the 5.2-5.6 range, and deviations from the ideal mash pH can hinder their efficiency, leading to incomplete conversion and lower extract efficiency. If your pH during mashing is drastically out of range then these enzymes can also be denatured, essentially unfolding the protein structure and rendering the enzyme damaged. If the mash is maintained between a pH of 5.2-5.4 your mash can be fully converted extremely quickly, in as little as 10 minutes. 

Yeast Performance: Yeast health and fermentation are also influenced by mash pH. A proper pH level ensures yeast viability, proper attenuation, and the production of desirable flavors and aromas. Incorrect pH can result in stressed yeast, off-flavors, or even stalled fermentation. 

Flavor Profile: Mash pH affects the extraction of various compounds from grains, including tannins and polyphenols. These compounds can contribute to astringency, harsh flavors, or undesirable mouthfeel if the pH is too high or too low. Achieving the right mash pH helps balance the flavors and enhances the overall beer quality.

Measuring Mash pH:

Accurate measurement of mash pH is essential for making adjustments. Digital pH meters, pH test strips, or color-changing pH indicators can be used. Choosing a pH measuring device that suits your budget is probably the most important factor. Digital pH meters are the easiest to use but require care and attention to ensure they stay calibrated. pH measurements should be taken 5-10 minutes into mashing. This way the mash has homogenised and the wide range of pH altering chemicals, proteins and more have become evenly incorporated throughout the grain bed and mash liquid. If you measure the pH of your mash and it doesn't sit between 5.2 and 5.6 you will need to use acidic or alkaline products to bring the mash pH into range.

Adjusting Mash pH:

Using Acids: If the mash pH is too high, acid additions such as lactic acid, phosphoric acid, or acidulated malt can be used to lower it. These should be added gradually, with frequent pH measurements, until the desired range is achieved. Lactic Acid is recommended for its authentic flavour profile and easy incorporation into the mash.

Using Alkaline products: Conversely, if the mash pH is too low, alkaline substances like calcium carbonate or baking soda can be added to raise it. Care should be taken to avoid overcorrection, as it can lead to undesirable flavours. 

Factors Affecting Mash pH:

Several factors can influence mash pH, including water chemistry, malt selection, grain bill composition, and temperature. Understanding these factors and their impact on pH can help brewers make informed decisions during recipe formulation and brewing process adjustments. The easiest way to get your mash pH spot on every time you brew is by paying very close attention to your brewing water. Water contains ions which will interact with your grain bill during the mash. The combination of grains and water chemistry is what leads to the mash pH you end up with. Brewing software such as Brewers Friend and Brewfather can allow you to easily create recipes and calculate how you need to alter water chemistry to produce great beers (and the right mash pH). These apps are also capable of calculating your mash pH before you begin, meaning you can add the necessary brewing salts to your water before beginning our brew day.