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Amt of IBUs from bittering addition--for IPAs

When you all are making recipes, just wondering about what % of the total IBUs you like to get out of the 60min bittering addition vs late hops?

I configure my recipes in reverse. I first determine the calculated IBU’s from my late additions, then add enough at 60 min to achieve my target overall IBU level. I don’t worry about a target percentage from the bittering addition.

Personally, I consider the late hop additions to be pretty much negligible as far as IBUs are concerned. I only calculate my 60-minute and 30-minute additions, and I generally shoot for about two-thirds of the IBUs from the 60-minute additions.

Can you clarify what you base this on? I don’t see how that could work as a rule of thumb. If you’re only using .5 ounce of a low alpha hop at 5 minutes, sure that would be negligible. If you’re loading up with high alpha hops, you get a meaningful level of isomerization.

Here’s an example of an APA I brewed yesterday. Total predicted IBU’s: 42.6.

0.40 oz Columbus (Tomahawk) [15.00 %] - Boil 60 min 18.3 IBUs
1.00 oz Centennial [10.50 %] - Boil 10.0 min 11.6 IBUs
0.25 oz Columbus (Tomahawk) [15.00 %] - Boil 10min 4.1 IBUs
1.00 oz Centennial [10.50 %] - Boil 5.0 min 6.4 IBUs
0.25 oz Columbus (Tomahawk) [15.00 %] - Boil 5.0 2.3 IBUs
1.00 oz Centennial [10.50 %] - Boil 0.0 min 0.0 IBUs
0.50 oz Columbus (Tomahawk) [15.00 %] - Boil 0.0 min 0.0 IBUs

IBU calculations are not an exact science and this is especially true for IPAs. Late hopping such as whirlpooling, provides more IBU than you would suspect. I aim for 1/3 for FWH and 2/3 from late hopping or whirlpooling. I estimate the IBU contribution of whirlpool hops as half the whirlpool time. IE for a 1/2 hour whirlpool, 15 minutes.

+1 exactly

About 1/3 of IBUs from FWH, 1/2 from 60-min addition, and then the rest late works best for my tastes in an IPA. I’ve made a couple beers recently with only FWH and late additions and find that the bitterness fades very fast with a 30-40% reduction in perceived bitterness after only a month of aging.

Can you clarify what you base this on? I don’t see how that could work as a rule of thumb. If you’re only using .5 ounce of a low alpha hop at 5 minutes, sure that would be negligible. If you’re loading up with high alpha hops, you get a meaningful level of isomerization.

Here’s an example of an APA I brewed yesterday. Total predicted IBU’s: 42.6.

0.40 oz Columbus (Tomahawk) [15.00 %] - Boil 60 min 18.3 IBUs
1.00 oz Centennial [10.50 %] - Boil 10.0 min 11.6 IBUs
0.25 oz Columbus (Tomahawk) [15.00 %] - Boil 10min 4.1 IBUs
1.00 oz Centennial [10.50 %] - Boil 5.0 min 6.4 IBUs
0.25 oz Columbus (Tomahawk) [15.00 %] - Boil 5.0 2.3 IBUs
1.00 oz Centennial [10.50 %] - Boil 0.0 min 0.0 IBUs
0.50 oz Columbus (Tomahawk) [15.00 %] - Boil 0.0 min 0.0 IBUs[/quote]
No, I can’t really provide any scientific argument for ignoring the IBUs contributed by late hop additions. I guess I’ve just always stuck with what Ray Daniels said in his book “Designing Great Beers”, which is basically that late hop additions can be safely ignored as far as IBU calculations are concerned. In my experience, I’d have to say that this has turned out to be true.

[quote=“deliusism1”]Personally, I consider the late hop additions to be pret
No, I can’t really provide any scientific argument for ignoring the IBUs contributed by late hop additions. I guess I’ve just always stuck with what Ray Daniels said in his book “Designing Great Beers”, which is basically that late hop additions can be safely ignored as far as IBU calculations are concerned. In my experience, I’d have to say that this has turned out to be true.[/quote]
I’ll take your word for it that he said something like that somewhere. On page 82 (second edition) he recommends using the same process stated in my first post above–including formulas to calculate IBU contribution for early and bittering additions.

The reason I started the post is that I recently made an IPA with IBU of 76 (Calc by beersmith) with only 20 IBU from 60 min magnum bittering. 14 IBUs from centennial FWH, and the rest from centennial/columbus 15,10 and 5 min. It was bitter, but very smooth and pleasing if I do say so myself. I tested it against several commertial IPAs and most found it more pleasing with better hop flavor (which is of course personal preference). I was just wondering if it was that most of the IBUs were late?

Centennial/Columbus is a great hop combo!

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