Brewers use many tools to measure the success of beer production, and one of the most important is the pH meter. Here are a handful of ways that pH meters are used in the brewing process.
The mash is the stage where a brewer extracts sugar from malted barley and other grains. There are a number of variables that contribute to this process occurring, temperature being the key, but pH plays a big role too. The enzymes that activate in the mash tun between 62-70°C are called amylase enzymes. These operate by breaking bonds in long chains of dextrins and starches, leaving behind smaller chunks of sugar that can be consumed by yeast. At this stage, the brewer is looking for a pH range of around 5.2-5.5, the range at which the enzymes operate most effectively, thereby creating the most sugar. The pH is affected by the water and grains used, so if this pH window is missed, the brewer must begin to review their water treatment and maybe the raw ingredients too.
In the kettle, pH becomes important for a few reasons. It is here that hops are added to introduce bitterness and aroma to the beer. pH has an effect on this too. At this stage, a pH of around 5.2 is optimal for extraction of hop flavours. A higher pH is more efficient, but will also extract harsh and undesirable characteristics. This pH is also good since it reduces the colouring effect of the Maillard reaction - particularly useful if you’re making a light beer. This pH range also helps proteins to bond together thereby aiding their removal from the beer, which will result in a clearer and less astringent beer.
Finally the pH changes that occur during fermentation need to be monitored too. As the sugar is converted into alcohol by the yeast, one of the many other effects is that the beer becomes more acidic. This isn’t a bad thing. In fact, a pH of 4.2-4.4 in a finished beer is desirable, since at this pH a great number of spoilage microbes that might otherwise ruin the beer are inhibited from living in the beer.