IBUs - Let's get this sorted out.

Discussion in 'Beer Talk' started by Hop-Droppen-Roll, Jul 1, 2014.

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  1. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    "calculated IBU's" are based upon hop utilization estimators. A hop utilization estimator that is often discussed is the one developed by Glenn Tinseth but there are others (e.g., Rager, Daniels, etc.).

    At the recent National Homebrewers Conference there was a presentation on the topic of Scaling Hops that involved beers brewed by Columbus Brewing Company and a homebrewer. In that ‘study’ it was found that Tinseth, Rager and Beersmith underestimated the IBUs as compared to the measured values.

    In this particular instance the hop utilization estimators provided a worse indication of IBUs. I have no idea whether this necessarily also means a worse indication of perceived bitterness since there is no means to quantify perceived bitterness.

    Cheers!
     
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  2. TongoRad

    TongoRad Poo-Bah (2,612) Jun 3, 2004 New Jersey
    Society Trader

    Interesting. Was that for both batches, or just the commercial one that had a higher utilization than calculated? Also- were there comperable results for when the IBUs get in the extremely high range (i.e. over 100) or if the beer was high-gravity?
     
  3. hopfenunmaltz

    hopfenunmaltz Meyvn (1,436) Jun 8, 2005 Michigan

    I need to go back and look at that one. I think they were all low for the commercial system, can't remember what Frank had.

    Tinseth did his work homebrewing on a half barrel system when he was a grad student at Oregon State. I had 3 beers measured from my half barrel system, and two were pretty darned close to Tinseth. The DIPA that was to be something like 101 IBU calculated came out at 65 or so measured.
     
  4. nc41

    nc41 Poo-Bah (1,809) Sep 25, 2008 North Carolina
    Trader

    I get bitter, sweet, sour, not sure what the 4th would be. Most IPAs lean towards bitter , most dipas lean towards more sweetish due to the increased malt , sour is sour. A good IPA /dipa is a thing of beauty, and is really difficult in a crowded market. The worst are merely mediocre and forgettable. A favorite IPA is Headhunter IPA, really we'll done, HDR is an IPA that drinks like a Dipa, Sue, Dipa favorites = Ht/ Abrasive/ Juju/bodhi
     
  5. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    Michael,

    The ‘calculated’ IBUs for the Commercial Batches (three 30 BBL batches of Columbus IPA) are:

    · Columbus Brewing Company (CBC) estimate: 54.85 IBUs

    · Tinseth: 44.3 IBUs

    · Rager: 47.2 IBUs

    · Beersmith: 51 IBUs

    The CBC & Beersmith estimates came closest since they provide a bitterness estimate for whirlpool hop additions.

    The homebrew batches were three 15 gallon batches. Estimates were provided for the three homebrew batches (I think he used Beersmith?):

    · HB1: 54 IBUs

    · HB2: 54 IBUs

    · HB3: 56 IBUs

    The measured values were:

    · C1: 65 IBUs

    · C2: 62.4 IBUs

    · C3: 64 IBUs

    · HB1: 64.9 IBUs

    · HB2:

    · HB3: 61.5 IBUs

    I can’t recall the issue with HB2 and why there was no measured data for this batch.

    As you can readily see from the figures above, all hop utilization estimators (including the CBC estimator) underestimated IBUs for the commercial batches and the homebrew batches.

    You asked: “Also- were there comperable results for when the IBUs get in the extremely high range (i.e. over 100) or if the beer was high-gravity?” The only beers addressed in this presentation were commercial batches of Columbus IPA and the homebrewed ‘clones’ of Columbus IPA.

    Cheers!
     
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  6. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    Jeff, when you review the presentation you will see that Tinseth was the least accurate estimator for the Columbus IPA. One reason was that Tinseth does not account for whirlpool bitterness but neither does Rager and Rager provided a 'better' estimate.

    Cheers!
     
  7. Peter_Wolfe

    Peter_Wolfe Initiate (90) Jul 5, 2013 Oregon

    "Calculated IBUs" are utter nonsense. Seriously. As a homebrewer, I think one should be purely concerned with estimating mg/L of iso-alpha and just forget that the IBU assay even exists. If a professional brewer is "calculating" IBUs and putting that on a label, they should be ashamed of themselves. That will never be anywhere close to correct. Even if they're taking the time to run (the very simple) assay, the IBU number still means next to nothing for most craft beers.

    As far as the various estimators out there, I've found that every brewhouse will deviate a little bit (it gets especially weird when you mix pellets and whole cone hops, which have very different utilizations). Brewers using a calandria versus steam jacket will also deviate from the estimated utilizations. Utilization also changes a significant amount based on the gravity of your wort.

    You really just have to dial in your brewhouse and figure out your own utilizations.
     
  8. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    "Calculated IBUs" are utter nonsense. Seriously.”

    Peter, I appreciate why you made the above statement. I personally do not use any hop utilization estimators in my homebrewing practice. When discussing the topic of hop utilization estimators with other homebrewers I always emphasize the “estimator” aspect. I have never posted that these estimators are “utter nonsense” but I can understand why you feel this way.

    Cheers!

    Jack
     
  9. Peter_Wolfe

    Peter_Wolfe Initiate (90) Jul 5, 2013 Oregon

    Except that you're conflating "utilization" with IBU. Utilization calculators are supposed to estimate how much alpha acid is turned into iso-alpha acid. That's fine. That's step two or three in recipe design, no problem. Deriving an IBU from that is where I start to have a huge problem with it. I've run hundreds of IBUs (the actual assay, not a calculator), and they have never, not a single time, correlated 1:1 with iso-alpha ppm.

    In other words, the utilization calculator should have one output: iso-alpha. Turning that into an IBU number is just misleading hand-waving.

    That being said, people can do whatever they like, and good beer will be good beer regardless of what the label says. Sorry if I sounded grouchy about it :slight_smile:
     
  10. hopfenunmaltz

    hopfenunmaltz Meyvn (1,436) Jun 8, 2005 Michigan

    Yeah, now i remember a little of that. Need to go back and review it.

    Know your system, procedures, and where those are different from the assumptions in the estimators. I did point out that my numbers on a half barrel system were close to Tinseth, but I was not doing a whirlpool addition back then. I know if I did and had the beer analyzed, it would come out higher than Tinseth. I have my own swags for whirlpool additions.
     
  11. TongoRad

    TongoRad Poo-Bah (2,612) Jun 3, 2004 New Jersey
    Society Trader

    I'm all for dialing it in and letting my palate be the guide, and even had experience doing something like that a while ago. We were scaling one of my homebrew recipes up to 10 Barrels, and just used the original IBU Calculation as a starting point. After the first batch we thought the end result was too bitter, so we reduced it by a certain percentage and were happy with it from that point on.
     
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  12. TongoRad

    TongoRad Poo-Bah (2,612) Jun 3, 2004 New Jersey
    Society Trader

    I am really surprised that they were off by that much, and by inference the utilization percentages should be much higher in the calculations. I guess that does explain my experience I posted about above, though, where the beer came out much more bitter than I wanted.

    Was there any mention of coming up with a revised calculation based on this experiment?
     
  13. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    “Except that you're conflating "utilization" with IBU.”

    In all fairness I am not the person who is doing the “conflating”, it is the folks that are developing the hop utilization estimators. Not to single out Glenn Tinseth but…. It is Glenn Tinseth who developed an estimator that provides the results of IBUs (vs. iso-alphas). In other words with his tool you enter amount of hops for additions (along with their AA%) and ‘out’ comes an estimate of IBU.

    When you state “Turning that into an IBU number is just misleading hand-waving” you are preaching to the choir.

    To repeat what I mentioned previously: “I personally do not use any hop utilization estimators in my homebrewing practice.”

    Please continue to ‘preach’ about the inexactitude of the various hop utilization estimators (that provide results of IBUs) because I thoroughly support you on this topic.

    Cheers!
     
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  14. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    “Was there any mention of coming up with a revised calculation based on this experiment?” No.

    I have listened to a number of podcasts of Basic Brewing Radio where the host (James Spencer) has strongly ‘advocated’ to Dr. Brad Sturgeon of Monmouth College (a Chemist who performs IBU measurements and a frequent guest on BBR) that “somebody has to come up with a ‘better’ hop utilization estimator!”. Dr. Brad Sturgeon just meekly states something along the lines of: "there are so many variables that coming up with an ‘accurate’ hop utilization estimator is a very difficult task”.

    So, until “somebody” steps up to the plate we are left with what we currently have on hand: tools from Tinseth, Rager, Beersmith, etc.

    In all fairness these tools can sometimes come up with reasonable estimates. Just re-read what Jeff posted about his brewing system being consistent with the Tinseth estimator for a number of his batches. The ‘issue’ is that no hop utilization estimator is broadly ‘accurate’.

    Cheers!
     
  15. herrburgess

    herrburgess Meyvn (1,089) Nov 4, 2009 South Carolina
    Industry

    I wonder why, then, you continually quote Conrad Seidl about the perceived "drop" in IBUs among German pilsners and conflate it with a sign of drop in quality?
     
  16. JackHorzempa

    JackHorzempa Poo-Bah (4,007) Dec 15, 2005 Pennsylvania
    Society

    There is a distinction between hop utilization estimators and measured IBUs.

    As @Peter_Wolfe posted previously: "The IBU assay was developed in the 1960s, before liquid chromatography had been fully developed. It was also developed in a period where German style and American style lagers completely dominated the market everywhere but the UK. Therefore, the assay was developed using wet chemistry and dry lager beers. In that style of beer, the IBU number correlates with the perceived bitterness with a very high correlation coefficient ..."

    So for the case of commercial German Pilsners, measured IBUs is a fairly accurate measure of iso-alpha acids (bitterness).

    Cheers!
     
  17. herrburgess

    herrburgess Meyvn (1,089) Nov 4, 2009 South Carolina
    Industry

    That doesn't explain the U.S. styles you compare the Germans to in terms of IBUs.
     
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