When are bittering hops typically added during the brewing process?

Bittering hops are typically added at the beginning of the boil. This timing allows for the maximum extraction of alpha acids, which contribute to the beer's bitterness. The heat of the boiling wort is essential for converting these acids into iso-alpha acids, which impart the desired bitter flavor profile in the final beer.

Options that suggest adding hops during the last 15 minutes of the boil or after the boil is complete relate more to aroma and flavor hops. These later additions preserve the aromatic qualities of the hops while still providing some level of bitterness, but they do not achieve the same intensity as hops added earlier in the boil. Adding hops before the last 30 minutes could also be considered a strategy for balancing bitterness with the development of flavor but is not as common or definitive as starting at the beginning of the boil.

Thus, the practice of adding bittering hops at the beginning of the boil is a standard technique in brewing meant to achieve the desired bitterness in the finished beer.