Beer hops are typically added to wort in three stages during the boil: bittering, flavor, and aroma. These stages are based on the role they play in your beer and are not specific to a particular type of hop. In other words, the same hop variety can be used for bittering, flavor, and aroma. Not all beers require three hop additions; some may only have one, while others may have up to five or six additions. However, all beers must have at least one hop addition for bitterness to balance the sweetness of the malt.
Adding hops at different times gives your beer more complexity
If you only add bittering hops, the beer will be acceptable but lacking something. By adding aroma hops, you introduce another dimension to your beer. On the other hand, if you use only aroma hops, your beer will lack bitterness because not enough alpha acids from the hops will be isomerized during the boil.
The Hop Schedule
Most recipes will indicate when to add your hops either by time from the start of the boil or time remaining in the boil. For example, if your beer needs to boil for a total of 60 minutes, the instructions might tell you to add the bittering hops at either 30 minutes into the boil or 30 minutes before the end of the boil. Pay attention to how the recipe is written because it can significantly affect the beer’s bitterness.
When to Add Bittering Hops
Bittering hops are added once the wort has been collected in the kettle (or after adding malt extract) and a rolling boil has been achieved. They are usually boiled for 60 minutes, although some recipes call for as little as 30 minutes. All beers require some bittering hops. Without the bitterness from the hops, the beer would taste overly sweet. Additionally, hops act as a natural preservative, allowing the beer to stay fresh for longer periods or during aging.
When to Add Flavoring Hops
Flavoring hops are generally added with 15 to 30 minutes remaining in the boil. During this time, only a small amount of bitterness is extracted from the hops, but it imparts a crisp hoppy flavor. These flavoring hops can be the same variety as the bittering or aroma hops; the difference lies in the duration of boiling.
When to Add Aroma Hops
Hop oils responsible for aroma are highly volatile and will evaporate quickly during the boil. Therefore, aroma hops should not be boiled for an extended period. They are typically added during the last 5 minutes of the boil or at flame out (when the kettle is removed from the heat). Adding hops at flame out maximizes the aroma potential in the beer.