Why is the IBU coming out higher than expected?

Discussion in 'Recipes for Feedback' started by Brewer #88351, Apr 23, 2017.

  1. Brewer #88351

    Brewer #88351 New Member

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  2. jmcnamara

    jmcnamara Well-Known Member

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    Permission error. Trying resharing it
     
  3. J A

    J A Well-Known Member

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    There are several settings/specs that will change your IBU calculation. Addition time, AA numbers, late addition extracts, batch size/boil gravity. etc. That's a huge difference, so something is way off. As soon as you get the recipe searchable, you'll get some answers.
     
  4. Brewer #88351

    Brewer #88351 New Member

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    Hi Guys,

    Learnt how to share my recipes! :)

    The link is: https://www.brewersfriend.com/homebrew/recipe/view/460471/brewdog-punk-ipa-current-v1

    Cheers,
    JT

     
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  5. J A

    J A Well-Known Member

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    Checking the recipe, all I can see is that you have a butt-load of hops. The way that you have everything entered looks right. That can't be the hop schedule that the brewer is specifying for a 5 gallon batch to get 40 IBUs. The Chinook at 60 alone is giving you over 35.

    If those are the exact amounts and same AA that the brewer suggests then the only place there can be a significant difference is in the hop utilization of the whirlpool hops. And are they really specifying 60 minutes? And 199 degrees? Hop stand is usually a lower temp - 160-180F.
    I don't know if there's a way to really accurately compute utilization from whirlpool hops but if there's zero contribution at flameout (even though those hops are presumably left in during cooling) I don't think you can really get high utilization from whirlpool hops at the usual temps. Just by changing the hop utilzation to 2% the IBU changes to 43.76.

    I say double check the specs from the recipe because the answer is somewhere in you late hop calculations.

    BTW...you say you brewed it. Is it finished so that you can taste it? Or taste a gravity sample? Over 100 IBUs in a beer of that gravity would be pretty unmistakable and bitterness would be pretty harsh.

    Maybe post the source of the recipe you used to formulate your brew.
     
  6. Ozarks Mountain Brew

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    its the 10% whirlpool times, they add up,are you really whirlpooling for a hour starting at 200 with 4 hops, if so thats the added IBU
     
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  7. Brewer #88351

    Brewer #88351 New Member

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  8. Ozarks Mountain Brew

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    yes its the % of high alpha hops in the whirlpool, take that 10% out and it lowers
     
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  9. J A

    J A Well-Known Member

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    I don't find anything in that recipe that notes Whirlpool hops at all, much less for 1 hour at 199 - just flameout and dry hop. Is there something I missed that would give reason to approach it in any other way? If you just put all those hops in at 15min, flameout and dryhop for 5 days in secondary, you're going to get a ton of aroma.
     
  10. Mark D Pirate

    Mark D Pirate Well-Known Member

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    Do Brewdog state bitterness in Tinseth or Rager ?
     
  11. Nosybear

    Nosybear Well-Known Member

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    That was where I was going.... Different calculation methodologies yield different results. Absolutely, if you could measure it, IBUs measure the amount of isohumulone in parts per million (mg/l). Since most of us don't have a spectrophotometer in our basements, we calculate. There are several variables that affect how much humulone goes into the beer and how much gets isomerized, hence different calculations. It gets worse: Other compounds affect the perception of bitterness, even other alpha acids. Oxidized beta acid contributes bitterness. Some tannins can be perceived as bitter. Those 100+ IBU hop bombs, estimation is we can't taste that much bitter... Long and short of it, IBUs are approximations at best, misleading at worst. Don't worry too much about it except as a predictor, then adjust based on your actual outcome. And good luck with the beer!
     
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  12. Mark D Pirate

    Mark D Pirate Well-Known Member

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    Those of us that also no chill have extra variables , depending on weather my wort can cool in hours or overnight or even longer
     
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