Why is Mash pH Important?
Note that the pH of your brewing water, the pH of your wort, and even the pH of your finished beer can have an effect on your final product. Each of these areas could be articles unto themselves, so I won’t get into that too much here. For the purposes of this article, we’ll focus on where pH has the greatest effect and that is the mash.
First, what is pH again?
If you need a high school chemistry refresher on pH, check out this Wikipedia article.
In short, pH is the measurement of how acidic or basic (alkaline) a solution is. Water is generally smack dab in the middle of the scale at 7 (neutral) with the acid side of the scale going down to 0 and the alkaline side of the scale going up to 14.
Why is mash pH important?
Achieving a mash pH in the range of 5.2 – 5.4 offers the following benefits to your brew:
- Better mash enzyme activity, resulting in better conversion of starches into sweet, delicious sugars
- Better hop extraction in the boil
- Lower pH of your finished wort, leading to:
- Happy and healthy yeast in fermentation
- Inhibited bacteria growth
- Improved clarity and flavor of finished beer
Okay, so what pH should I be targeting?
In general, we want to target a mash pH on the acidic side of the scale with a value between 5.2 and 5.4.
Disclaimer: This is a widely debated and, in the eyes of some, a controversial topic. In the spirit of The Amateur Brewer, I want to keep this article short, sweet, and to the point. So needless to say that a mash pH in that range is widely accepted by some of the smartest and most experienced on the topic. You can find plenty of articles and forum entries on the internet (that will cause your eyes to roll back in your head) discussing the merits of pH values outside of that range. I’m not saying they are wrong, I’m just saying that a mash pH of 5.2 – 5.4 works. You may come across recipes or guides for particular styles that will call for a different pH target. In those instances, feel free to deviate from the 5.2 – 5.4 range.
It should also be noted that temperature can have a significant impact on pH readings. Nobody has time in the middle of a mash to be thinking about the temperature of their sample. Just know that a pH reading in the range of 5.2 – 5.4 at your typical mash temperature is what you are aiming for.
What effects my mash pH?
The two main things that are going to affect your mash pH are:
- Water – There are entire books that have been written on the subject of the science of brewing water. I’m not even going to try to get into it here. Perhaps I’ll scratch the surface in some other articles. Suffice it to say that the pH of your water (being a main ingredient in your beer) will have an effect on your mash pH.
- Grain – Malted grains tend to be acidic and help to lower your overall mash pH. Darker grains tend to be more acidic than lighter grains. So your darker beers will probably need less pH manipulation than your lighter beers.
The pH of water in different locations and the pH of various grains can vary by quite a bit. So pinpointing your mash pH based on the chemistry of your water and the pH of your grains can be difficult. In general there are a lot of brewing calculators and software that will help to get you close. But testing your mash pH with testing strips or a meter is a must (I’ll cover this in another article). I recommend testing about 5 minutes into your mash. Then make your adjustments and then test again about 5 minutes later. Repeat as necessary to achieve the target of 5.2 – 5.4.
Wait, how do I adjust my mash pH?
There are several ways that you can adjust your mash pH to target the 5.2 – 5.4 range. The vast majority of the time, you’ll be looking to lower your pH (I’ve actually never encountered a time where I needed to raise my mash pH). So I’ll focus on those methods:
Acid Malt
This is typically a pale malt that has been subjected to lactic fermentation, thereby leaving it acidified with lactic acid. For each 1% of your grain bill, you’ll generally see a drop of about 0.1 on the pH scale. The general rule of thumb is that you can use this up to 10% of your grain bill without any ill effects on the taste of your beer.
Lactic Acid
This is an organic acid produced through a fermentation process (as noted above). You’ll generally find this in liquid form at an 88% concentration (though that can vary, so pay attention to the label). There are some varying opinions on the maximum amount that should be used in the mash. You should be safe at 1.5 mL per gallon of your mash water without affecting the flavor of your beer.
Phosphoric Acid
While I know that there are brewers that use this with success, phosphoric acid can affect your water chemistry in other ways besides pH. It is a complex water chemistry topic that I won’t get into here. Bottom line, do some additional research on its effects on your water chemistry before using.
“5.2 Stabilizer”
This buffering agent is another solution that I know some brewers use with success. But it can affect other aspects of your water chemistry, particularly the amount of sodium. Let’s call this one what it is…the lazy man’s solution to mash pH. In the long run with this great hobby, you’re better off actively measuring your pH and learning to use some of the other methods to address the target pH range of your mash.
This one got a little longer than I intended, but I hope that answers your questions about the importance of mash pH. As stated previously, there will be some differing opinions out there on the topic. I welcome any questions, comments, or differing opinions in the comments section below.
