Scaling aroma hops

[Stikius]

How do you scale aroma hops from different batches (different alpha acid composition)? Let's say I have written a recipe that calls for the 5% alpha acid Hallertauer Mittelfrüh I had at home when writing the recipe, but the next batch I bought only have 3%.

For bittering hops it's easy, just aim for the same IBU. But what do you do with aroma hops? I usually use the same amount of hops as the recipe calls for and ignore IBU, but really interested in what others are doing. Been searching around the forum and can't find any discussions at all on this topic.

 

[Brushwood Brewing]

I'd say it might vary based on what you mean by "aroma hops". If you mean hops added within the last 10 minutes of the boil, yes I might consider increasing the amount of hops based on a lower AA percentage. But if it's a cooled whirlpool or dry hop, I probably wouldn't care about the difference in AA percentage.

Obviously the hotter the hop addition, the more the difference in AA percentage matters. That being said, I'd probably ignore the AA difference if it was more convenient for me, for example to use up a whole bag rather than using just a partial.

Or you could always adjust the time you add them, instead of the amount: For example, if the late addition hops have a lower AA percentage you could bump them up a few minutes earlier in the boil. Use a IBU calculator to make that call.

 

[Stikius]

Thanks, and sorry for not being very specific. I was actually thinking about a late boil addition, but the question would apply to both that and a whirlpool/hopstand. For dry hops I wouldn't really care about AA at all.

 

[Kickass]

I’d keep the late addition hop quantity the same. If that equals a less than desirable IBU then I’d make up for the IBU deficiency with more early boil hops.

I’m more inclined to treat my early hops as the IBU contribution and late hops as the flavor and aroma…within reason.

 

[Stikius]

Good idea, never thought about making up for "aroma IBU" with bittering hops. Will definately give it a try!

 

[Agent]

I was wondering this recently as well.

Since you'd desire a consistent amount of total oils in the dry/aroma hops, but most recipes or packages only list the AA%. So did the AA just slip, or is the total oil content equally affected?

Just questions without answers...