Hop AAU adjustment?

I have a question about following recipes...

Lets say a recipe calls for 1 oz. of Cascade hops @ 9.6% aau. If I purchase cascade hops that are say 9.3%, should I adjust the amount? Also, which formula is best for doing this???? thanks!

with such a similar AA%, you wouldn't need to in this case. but the way to convert is multiply the AA% and weight for the recipe. 1 x 9.6 = 9.6. then divide that by the AA% of your hops, 9.6/9.3 = 1.03. so you'd need 1.03 oz of 9.3% cascades to = 1 oz of 9.6% cascades.
say you have a recipe that calls for 1 oz of 9.3% amarillo, but you have 10.4% amarillo, using the same math, you'd need .89 oz of the 10.4% amarillo for that recipe.

nice, thanks! At what point should I worry about adjusting the amount? What AAU difference...

Just throw your recipe into http://beercalculus.hopville.com/recipe
and choose your AA% and it calculates it for you.

awesome. thanks for that link! Ive been looking for something like that!

mikesalvo said:

nice, thanks! At what point should I worry about adjusting the amount? What AAU difference...

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mainly bittering additions (early in the boil hop additions). AAUs are translated into IBUs by a function of AA%, time, and specific gravity.

As mentioned, AAUs are easy to caculate by hand; IBUs are not.

So, if you are targeting a specifc IBU #, you can use software to determine what you need based on the AA%/AAU.

Please note that you SHOULD NOT adjust a recipe's flavor or aroma additions based on a different AA%. AA% is useful only for bittering. The flavors and aromas come from other compounds. So if your recipe calls for 1 oz of Cacades at 10 minutes, throw in 1 oz of Cascades at 10 minutes, regardless of the AA%. Of course this means you may need to readjust your bittering addition to keep the total IBUs the same, beyond your original adjustment for AA%.

At what point in the boil are the additions considered flavoring hops? With a 1.8-2% AAU difference between what I have ad what the recipe calls for, should I STILL not adjust my flavoring weights?

Here's one good example showing you what you get from different lengths of the boil.

mikesalvo said:

At what point in the boil are the additions considered flavoring hops? With a 1.8-2% AAU difference between what I have ad what the recipe calls for, should I STILL not adjust my flavoring weights?

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Correct. If you're adding hops at 15 minutes, those are your flavoring hops. Adding more to adjust the IBUs means that you'd add more (or less) hops. The flavor is a complex thing, and IBUs really don't matter much as compared to the flavor you're getting.

I'd say any hops added at 20 minutes or less shouldn't be adjusted for AAUs, as they are for flavoring and aroma.

Yooper said:

Correct. If you're adding hops at 15 minutes, those are your flavoring hops. Adding more to adjust the IBUs means that you'd add more (or less) hops. The flavor is a complex thing, and IBUs really don't matter much as compared to the flavor you're getting.

I'd say any hops added at 20 minutes or less shouldn't be adjusted for AAUs, as they are for flavoring and aroma.

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great! and I assume dry hop additions should also not be altered?

mikesalvo said:

great! and I assume dry hop additions should also not be altered?

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Correct!

Kealia said:

Here's one good example showing you what you get from different lengths of the boil.

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I've seen you show this chart in other posts. Did you ever find the original source? I'd love to read whatever went with it. Thanks!

smyrnaquince said:

I've seen you show this chart in other posts. Did you ever find the original source? I'd love to read whatever went with it. Thanks!

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I've seen that graph in lots of posts before too. It really is a generalization - not sure there's anything more to read about it. Hops are complex mixtures of 100s of compounds, so it will never be as cut and dry as that figure suggests. But it does a good job of emphasizing the relationship between hop bitterness, flavor, and aroma in terms of hop addition times.