Which two alpha acids are isomerized during the boil?

The isomerization of alpha acids during the boil is a fundamental process in brewing that transforms the bitter compounds found in hops into forms that contribute to the beer’s bitterness. Humulone and cohumulone are both alpha acids naturally present in hops that undergo this isomerization.

Humulone, the primary alpha acid, isomerizes to form iso-humulone, which is responsible for the characteristic bitterness in beer. Cohumulone, another significant alpha acid, also converts during the boil to iso-cohumulone, enhancing the overall bitterness profile. The transformation of these alpha acids is crucial for developing the desired flavor and aroma characteristics in beer, making them integral to the brewing process.

The other combinations listed do not fully represent the alpha acids that undergo this isomerization. Adhumulone is an alpha acid as well but does not yield the same transformation as humulone and cohumulone during boiling. While myrcene is a hop oil compound that contributes to aroma, it is not an alpha acid and does not undergo isomerization to form bitterness. Likewise, iso-alpha acids refer to the resultant forms of the isomerized alpha acids, emphasizing that the original materials in question are specifically humulone and co