The pH value has various effects on beer, so it is important to monitor the pH value of the wort at different stages of the brewing process. We specifically focus on studying the impact of pH during the boiling process.
One of the main reasons for controlling pH during brewing is to prevent excessive extraction of tannins. Most tannin extraction occurs during mashing and sparging, primarily from grains, but hops also contain tannins.
Tannins are soluble compounds that can impart a strong astringent taste to beer. To experience this effect, imagine reducing the dryness and astringency of tea to the level of tannins. By weight, hops contain only about 2-5% tannins, but they can contribute up to 20% of the tannins in the final beer.
Copper Beer Brewing Equipment
So how do we control this extraction? Well, there’s not much we can do except reduce the amount of hops used or decrease plant material during boiling. If you’re a brewer who uses whole hops during boiling, you might consider using pellets to minimize tannin extraction.
Maintaining the correct boiling pH (around 5.1) also helps with protein coagulation. Proteins consist of amino acids, including hydrophobic amino acids that try to avoid water. These amino acids interact with each other instead of water as proteins denature, but as the protein solidifies, some of the hydrophobic amino acids become exposed on the surface. To avoid moisture, these amino acids combine with hydrophobic amino acids from other coagulated proteins to form larger, heavier protein clumps that precipitate out of suspension along with tannins and hops.
As the boiling pH decreases, the hydrophobic parts of proteins more readily react with each other, causing faster clumping and precipitation. The most effective pH for this is 4.9, which means brewers can boil at a lower pH (below the usual 5.2-5.4 range) to achieve more efficient protein coagulation, though this will reduce hop utilization.
The solubility of hop isoacids depends on temperature and pH. Solubility increases with higher pH, so a higher boiling pH actually allows for better hop utilization and bitterness extraction, even though the bitterness extracted at higher pH is considered harsher than at the normal pH range (5.2-5.4). During fermentation, the beer’s pH will further decrease, causing unisomerized hop resins to precipitate out of suspension.
Lastly, the pH during boiling greatly affects the color of the beer. A higher pH leads to darker wort during boiling due to increased production of melanoidins. If you want a lighter beer, pH should be a key consideration.
Finally, if your mash pH and sparge pH fall within acceptable ranges (mash pH of 5.2-5.4 and sparge pH below 6.0 during runoff), your boiling pH should also remain within an acceptable range. pH usually drops by approximately 0.1-0.2 units during boiling.
Do you measure pH throughout the brewing process or take it into account when planning your recipe? Please send an email to info@ace-chn.com
