Why are we guessing at hop utilization percentage?

Discussion in 'General Brewing Discussions' started by J A, Jun 6, 2018.

  1. J A

    J A Well-Known Member

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    It seems to me that it should be a matter of calculation, embedded in the calculator settings. If whirlpool hops are adding IBUs and perceived bitterness based on time and temperature (and whether the wort is in motion or still), then we shouldn't have to choose a hop utilization rate based on a best guess and informed by subjective observation. It's either determined by time temp and motion or it's not.
    Thoughts?
     
  2. Nosybear

    Nosybear Well-Known Member

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    Agreed, mostly. I was looking for information on late hop utilization last night and it's notably missing. The calculators almost all assume 0% utilization for hops added at flameout or later and, if you go with the strict definition of IBUs, it's likely close to true: Alpha acids don't isomerize below about 180 degrees F. Hop acids will isomerize above that temperature so if you don't cool your wort to 180 before adding late hops, you get some IBUs. The difficulty is that the perception of bitterness is subjective. And iso-alpha acids are not the only contribution to bitterness. If there's research out there - my Internet search turned up little useful information - I agree, we should incorporate it - it would make prediction of the outcome of our brewing quite a bit easier. Until then, it's empirical, read, trial and error.
     
  3. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Are you talking about the whirlpool additions? I have adjusted those, they default to 10% on Brewers Friend and when I whirlpool I back it down to 3%, but I'm guessing its's closer to 4%. I whirlpool between 160-170F and it's usually the main bittering addition. Despite all the talk that hops don't isomerize below 180F, I get a lot of bitterness, enough that I have made IPA's without any boil additions. Other brewers have found the same thing.

    So, if you want to calculate the amount of bitterness your going to get from the whirlpool, it's a guessing game. I found that 3-4% was about as close as I needed. Variations in stirring, temperature and time all change the hop utilization, I think temperature is the biggest influence. Raising the temperature of the whirlpool does affect the utilization, no doubt, but it doesn't magically stop at 180F. Time doesn't seem to make a big difference, at least 20 minutes compered to 40 minutes. Stirring, I'm assuming, helps to extract the hops oils associated with flavor/aroma.

    That's my two cents, although it may be worth less than even that.
     
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  4. J A

    J A Well-Known Member

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    Yes, whirlpool hops, though there's something to be discussed about flame-out additions left to whirlpool, which would be same as a no-chill period, I suppose.
    My question is a more fundamental one, though the notion of incorporating more of a predictor into the calculator is implicit. Yes, there are variables in literally the stirring or circulating motion of the wort and probably whether the hops are thrown in loose or in a bag, and as you point out, that's probably more of a flavor/aroma change. The big factors in isomerization (main contributor to actual bitterness) are time and temperature. It just seems like there should be a better idea based on scientific formulation. Surely big craft breweries don't have to make a WAG when they decide on a different hopping schedule to make a new recipe.
     
  5. Nosybear

    Nosybear Well-Known Member

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    They likely do something similar to us: They make a first approximation, then adjust. I went looking last night for a more scientific way of estimating and came up empty. Lots of chatter and rules of thumb, nothing I'd call science. So for now, I'll use the calculator here and adjust on a batch-by-batch basis.
     
  6. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    I guess that’s why brewing is an art that uses science, but it’s often treated like a science and it shouldn’t be. A great brewer uses intuition and experience, along with trial and error to produce great beer. I kind of like it that way, even with the screw ups. It’s like cooking, a good chef doesn’t always use precise recipes, they let their experience and intuition guide them.
     
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  7. J A

    J A Well-Known Member

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    I don't disagree with any of that^^^...but we're happily using a very scientific and formulaic approach to hop additions right up to the point that the flame gets turned off. And then it's anybody's guess as to what might happen?
    I firmly believe that it's more predictable than it seems to be but without the same sort of rigor that has obviously gone into predicting IBU contribution for boil addition hops, we're going to be stuck, apparently along with the entire brewing industry, just trying to figure it out on our own. ;)
     
  8. Nosybear

    Nosybear Well-Known Member

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    The formulas we apply to the boil are approximations, too. If we could test our beers - the equipment required is a bit out of my price range - we'd likely find out that we're missing the mark by quite a bit every brew. I think you're right that it might be possible to approximate whirlpool hops' contribution to bitterness more accurately and I'm sure if we went out to actual brewing chemistry journals someone has done so. But for now it looks like we'll have to live with the approximations we have. Part of the art.
     
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  9. Head First

    Head First Well-Known Member

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    From what I understand about hops we don't fully understand them:confused:. We cannot chemically replicate them, or duplicate them. So if there is stuff in hops we can't copy how can we design software to replicate what they do to beer? It is helpful to have a general idea of what you are building but I like the magic part of brewing. Some day we (or our great grandkids) will do it differentially.:(
    Professional brewers replicate what they brew, on a different level but still the same, replicate.
     
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  10. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    IBU is not all that scientific. It all about perception. Even with lab equipment it won’t be any different. Often the lab results do not correspond with the human tongue. I remember a well know DIPA brewer (his name escapes me) brewed a beer that he thought was about 90IBU’s, he spent the money to have it analyzed at White Labs and they measured the IBU’s at 30. What’s more important, what the human tastes or what the lab equipment says?

    Don’t get hung up on a lab result, trial and error leads to experience and consistency. The skill of the brewer is the most important part of that equation, and skill comes with time.
     
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  11. Head First

    Head First Well-Known Member

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    I will stick with magic. If we are using an ingredient that can't be replicated I'm good with that. Just one of the reasons homebrewers are on the front of brewing tech.
     
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  12. J A

    J A Well-Known Member

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    Fair enough, but I don't see a utilization percentage box to fill out in those parts of the calculator. Obviously there's enough of a formula to give a close approximation that we can take for granted, place some faith in and agree that results will be consistent across brews ...all without the guesswork involved in deciding where to set the percentage when attempting to "calculate" whirlpool contribution.
     
  13. Trialben

    Trialben Well-Known Member

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    Trial and Error. Brew one all whirlpool hops added at 80c after flame out whirlpooled for half an hour or whatever time. Taste beer see if it lines up with expected bitterness at 10% utilization. BREW 2 brew all whirlpooled beer again with adusted utilisation by perception of previous batch. Taste beer adjust utilisation from there. Eventually youll find your mean point then set this as your hop utilisation then within reason youve got a replicable dialed in tool for future hop bombs?
     
  14. Nosybear

    Nosybear Well-Known Member

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    If you select "whirlpool" as the hop type, you can adjust the utilization. You can also set your temperature at the start of the whirlpool - I think the calculator must make some adjustment about the cooling rate. Current default is 10%, since boiling here at 6,000' is about 200 degrees, I set it at 5%. We'll see how that works. I share your pain but find myself in a trial-and-error situation as well.
     
  15. J A

    J A Well-Known Member

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    Yes, we can choose hop utilization percentage...and that's my point. It's a total guess. While the factors involved in actually calculating the IBU contribution, percieved or otherwise, are undoubtedly connected with heat and time (and motion?) the only factor that makes a change in the IBU figure in the recipe calculator is the percentage. If I plug in 2 ounces of Centennial for a 20 minute whirlpool starting at 180 with the default 10% utilization setting, the contribution is a little over 27 IBUs. When I change the time to 10 minutes or 120 or 1, the IBUs remain constant. When I change the temp to anything higher or lower...same result. The only variable that has any bearing on the IBU estimate is percentage. The other settings are completely superfluous and we're just guessing without the benefit of any ability to calculate...so WAG and trial and error it is.
    The only way to get close to any real data would be to brew identical beers with one being bittered only with boil hops and being a baseline in terms of bitterness compared with calculated IBUs. Then brewing with the same hops in a whirlpool at 180 or so and monitoring the temp drop to know time spent above the threshold of isomerization. Comparing several batches and finding where the whirlpool hops seem to match up with the boil hops and finding the utilization setting that calculates the same IBUs would give an actual place to start.
     
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  16. The Brew Mentor

    The Brew Mentor Well-Known Member

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    Variables are what makes it interesting.
    Although we can use science to establish a baseline, the variables are endless and part of it will always experimental and learning.
    I do agree that there has to be a more precise way to set a baseline for the whirlpooling. And, who set the default to 10% and based on what data?
    Bitterness can be perceived on things other than IBU contribution as well.
    What about other bitter variables? CO2 levels, roasted malts, astringency, yeast, hop debris and others.
    It would be nice if we could get a lab involved to do some testing.
    If we could, and they did the testing for free, is there a way we could recognize them on BF?
    There's a lab in Columbus that I could ask, but I'd need some offering.
    Thought?
    Brian
     
  17. Ozarks Mountain Brew

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    water is also a huge issue you can have soft water or hard and the bitterness is different
     
  18. Nosybear

    Nosybear Well-Known Member

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    And everyone perceives the bitterness differently.... I don't think there's any way to factor subjectivity out of it! If there were, to hijack another thread, we wouldn't need judges - we could just run our beer through a gas chromatograph or some other instrument and voile! We have a winner. I remember when Wade and I brewed the common we won GABF silver with: I had used Brewer's Friend to estimate bitterness, his software gave a completely different result so we ended up tasting beers to find the IBU level we wanted, then calling an audible on the amount of hops to add. So there has to be some simplification to make the model useful, perhaps we have the right one in estimated utilization percentage, maybe not. Let's brew some beers and find out!
     
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  19. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    I prefer the way the calculator is setup, being able to adjust the whirlpool utilization is an awesome tool. For me dialing in my numbers in did take some time, but the variables are endless. I was able to use that tool to accurately predict my bitterness and replicate with other beers. Please don’t screw with a good tool.
     
  20. J A

    J A Well-Known Member

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    Here's a question...since you were able to dial in and predict IBU numbers as a result of arbitrary utilization settings, how did you go about deciding that X hop at Y time and temp yielded Z IBUs?
    Compare bitterness with other beers that were of a known IBU number?
    Compare with your own beers that didn't have whirlpool additions but had an IBU number generated from boil hops in the calculator?
     

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