Importance of Testing pH Levels in All Grain Beer Brewing

Brewing delicious grain beer relies on the pH level in your mash, as this directly impacts, the flavor of your beer. pH is the measurement of how acidic or alkaline a solution is. It is measured on a scale from 0-14 with 7 being a neutral reading. A pH Reading below 7 would be considered “acidic”, and a pH reading above 7 would be “basic”.

You must measure and then adjust the mash pH for each batch you brew. You can measure the pH with either a pH meter or pH test strips. While a large brewery may test the pH level of their water, their mash, the wort, and the finished beer, home brewers making an all-grain brew will generally focus their attention on the mash pH while it is in the insulated mash tun. 

Optimally, the pH of the mash should be in the 5.2 through 5.5 range. In fact, a lower mash pH (near 5.2) would provide extra benefits, including improved enzyme activity during the mash, leading to better conversion of starches to sugars; lower pH in the finished wort, which improves yeast health (which in turn inhibits bacteria growth); improved clarity in the finished beer; improved flavor; and clarity stability as the beer ages.

In most cases your measured mash pH will be too high, which means you will need to add an acid or buffering agent to the beer to adjust it down. There are many options available for this step:

Lactic Acid – An organic acid produced by bacteria and sold in liquid form. It's added a little at a time until you reach your target pH. It generally mixes well with beer flavors in the small quantities needed to adjust a typical mash.

Acid Malt – This is typically pilsner malt that has been acidified using lactic acid and contains about 3% acid by weight.

Phosphoric Acid – An inorganic acid which replaces bicarbonate with phosphate and increases the phosphate content of the wort.

Buffers – Stabilizer salts lower the mash pH by reacting with phosphates brought in by the malt.