Hop utilization

[Terry Zwart]

Jay was telling me about this and sent the write up.

I had no idea there was that much of a difference in hop utilization based on elevation.

Good read if you have never dug into it.

https://beersmith.com/blog/2019/12/08/high-altitude-beer-brewing-and-hop-utilization/

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Terry Zwart

6804 Lakota Ct

Loveland, CO. 80534

720-346-1464

[Blake]

Great article.  Thanks for sharing.

 

Blake

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[Ham Fon]

I think that the BeerSmith adjustments are too aggressive and would over-bitter the beer.  I base that statement on subjective personal experience, which may be meaningless (at least to anyone other than me).   Note that the discussion here is ONLY about the bitterness (and hop bittering utilization) - so the 20-minute, 5-minute, whirlpool, and any other hot-side hop additions would have less of an effect on the bottom line bittering (although they still account for some).

My recipe calculator (I wrote it 20-ish years ago, and it still does what I need) uses the Garetz formula (from his book "Using Hops" - 1994, I think) for calculating an altitude factor for bittering.  At 5280 feet (which is the altitude on the water tower for our community), BeerSmith says around 65% (I don't have BeerSmith, but looking at the table from Terry's BeerSmith link, that's close) utilization, indicating the need to add additional hops to cover the other 35%.  The Garetz formula gives me 83.89% utilization.  So, I compare the 0-altitude IBUs and the 5280-altitude IBUs and bump up the bittering hops at 5280 to match the 0-altitude IBUs (or I just set the altitude in my recipe calculator and shoot for the right IBU number).  That's generally about 20% more.  Also, note that making up from 83.89% to 100% takes more than the difference (16.11%) because those additional hops are also being under-utilized.

One other thought - if you don't have traditional (60-minute/90/120/etc.) bittering hops, and you are hop-bursting and getting your main bittering charge from a 20-minute colossal hop addition, it seems like a recipe calculator that does the altitude adjustment should still give you reasonable estimates.

Of course, this is all subjective because if you can't compare the identical beer brewed at 0 and 5280 feet, you won't really know that your at-altitude adjustment is "correct".  And it also begs the question of whether the IBU number gives you an accurate reading on bitterness (it doesn't - but it kinda gives you a ballpark indication).  What's important is perceived bitterness, not actual measured bitterness or measured IBUs.  Hey, wait - how did I get off on this tangent?  :).

Then again, if you're testing the two beers - do you drink them on the beach or at the base of the mountains?  That's a completely unrelated argument, and has more to do with carbonation :)

Nelson

Nelson Crowle, Principal Engineer

727-534-6944 (cell/text)

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[M B Boesen]

Lots of good stuff in this thread.  

1. from a 1997 Zymurgy article by Michael Hall:

"The overall utilization rate is the product of the boil time utilization rate (or uncorrected utilization rate) and all of the correction factors:
U% = U%bt x Fbg x Fhf x Fhr x Fbp x Fst x Fhbx  Fyf x Ffil ,
where the Fs stand for correction factors for boil gravity, hop form, hopping rate, boiling point temperature, storage losses, hop bags, yeast flocculation rate and filtration, respectively.
All of the F variables are nominally equal to unity, so you may omit any that don’t seem necessary to you."

2. from https://alchemyoverlord.wordpress.com/2016/03/06/an-analysis-of-sub-boiling-hop-utilization/ 

empirically derives a formula { U (T) = 0.11245 e0.01031T (where T is temperature in °F) } to indicate 91% at 203°F.

Personally I allow 10% for altitude (boil at 203°F), another 10% for putting my hops in bags, and a wild swag at allowing for the age of my hops.

3. Another is the article:  Tracking IBU Through the Brewing Process: The Quest for Consistency byAaron Justus Director of R&D and Specialty Brewing, Ballast Point Brewing

This one made me question whether IBU indicated in a recipe is for the wort, or the finished beer.

I will be glad to share pdf files for 1. or 2. above.