Dry hopping does not directly add bitterness to beer in the same way that traditional hopping with bittering hops does. When hops are added early in the brewing process, during the boil, the heat causes the alpha acids in the hops to isomerize, creating bitter compounds known as iso-alpha-acids. These iso-alpha-acids contribute to the perceived bitterness of the beer.
However, when hops are added during dry hopping, which typically occurs after fermentation, the hops are not exposed to heat and therefore do not undergo isomerization. This means that dry hopping does not add significant amounts of iso-alpha-acids and does not contribute directly to the bitterness of the beer.
That being said, dry hopping can still affect the perception of bitterness in beer. One way this happens is through the increase in pH that occurs when hops are added. Dry hopping can raise the pH of the beer, and a higher pH can lead to a more perceived bitterness. This is because the increased pH enhances the solubility and extraction of bitter compounds from the hops, including humulinones.
Humulinones are bitter compounds found in hops, and they are extracted during dry hopping. However, humulinones have been found to impart a “smoother” bitterness compared to iso-alpha-acids. They are perceived as being 66% less bitter than iso-alpha-acids. This means that even though dry hopping may increase the overall bitterness perception of the beer due to the pH increase, the type of bitterness from humulinones is often described as more pleasant and less harsh.
It’s important to note that the overall impact of dry hopping on bitterness can vary depending on factors such as the amount and type of hops used, the duration of dry hopping, and the specific beer recipe. Additionally, other compounds and flavors from the hops, such as essential oils, can also contribute to the overall sensory experience of the beer.
While dry hopping does not directly add bitterness through iso-alpha-acids, it can increase the pH of the beer, leading to a perceived increase in bitterness. However, the bitterness imparted by humulinones from dry hopping is often described as smoother and less harsh compared to iso-alpha-acids.