When does alpha acid isomerization occur?

Alpha acid isomerization occurs primarily during the boiling stage of the brewing process, when the hops are subjected to heat. The correct answer indicates that this process initiates effectively around 185°F, where the heat is sufficient to begin the transformation of alpha acids into iso-alpha acids, which contribute to the bitterness and flavor of the beer.

While it is true that hops are typically added to the kettle when the wort is brought to a boil, the actual isomerization process begins at around the 185°F mark and continues until the boiling point of 212°F is reached and maintained. Therefore, although boiling does play a crucial role and the fermentation process does not relate to isomerization of alpha acids, it is the temperature and not the act of boiling per se that initiates the isomerization.

Understanding that isomerization begins around 185°F is important because it helps the brewer control the bitterness level in the final product. The implications of this process are significant for achieving the desired flavor profile in beer.