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Old 09-27-2007, 12:16 PM   #1
RotorHead6
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I have a recipe that I will be brewing this morning. The recipe calls for Hallertau Pellets 4.5% alpha acids. When I went to the local home brew shop they only had Hallertau 4.2% Alpha acid.

My question is how do I do the math to figure out how to add more/less hops to my brew? Thanks for the help.
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Old 09-27-2007, 12:45 PM   #2
Khirsah17
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The equation for calculating AAU is:

AAU = AA (%) X Hops (oz)


So in your case, if the recipe calls for 3 oz of Hallertau at 4.5% AA,

AAU = 4.5 X 3 = 13.5 AAU

So you can use that to solve what the amount of hops you need at 4.2% to still get you the same AAUs.

Hope that helps!

 
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Old 09-27-2007, 02:33 PM   #3
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Just to finish that up:

Hops (oz) = AAU / AA (%)

So, Hops (oz) = 4.5/4.2= 1.07

So, you need 1.07 oz of 4.2% AA hops for every 1 oz of 4.5% hops in the recipe. In other words, you need a little more


TL

 
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Old 09-27-2007, 02:50 PM   #4
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Quote:
Originally Posted by TexLaw
Just to finish that up:

Hops (oz) = AAU / AA (%)

So, Hops (oz) = 4.5/4.2= 1.07

So, you need 1.07 oz of 4.2% AA hops for every 1 oz of 4.5% hops in the recipe. In other words, you need a little more


TL
In other words, not enough more to bother figuring it out.
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Old 09-27-2007, 02:51 PM   #5
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Quote:
Originally Posted by FSR402
In other words, not enough more to bother figuring it out.
Yep. But, I miss doing arithmetic sometimes.


TL

 
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Old 09-27-2007, 03:03 PM   #6
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I brought this up a LONG time ago....

...if nothing else, my first post has another explanation for the equation. The answers you've gotten so far suffice though. Just offering more.

http://www.homebrewtalk.com/showthread.php?t=2887
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Old 09-27-2007, 04:36 PM   #7
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use two extra hop pellets
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Old 09-27-2007, 11:14 PM   #8
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1 oz of any hop at a AA rating is the AAU of that hop.

For instance 1 oz of 7.1 AA cascade would be 7.1 AAU's
1 oz of 6.3 AA cascade would be 6.3 AAU's

If you needed 7.1% AAU's of cascade and had 6.3% then you divide 7.1 by 6.3 to get 1.13 oz.

And if you had 7.1 and needed 6.3 then divide 6.3 by 7.1 to get .89 oz.
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Old 09-28-2007, 01:30 AM   #9
RotorHead6
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Thanks for all of the help. I successfully hopped da brew.
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