Hop utilization

Discussion in 'General Brewing Discussions' started by EvanAltman36, Mar 1, 2013.

  1. EvanAltman36

    EvanAltman36 New Member

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    Man, you guys are probably getting really tired of my questions, but I just came up with another one. The boil size doesn't appear to impact OG or anything related to the content of the wort, but it does greatly impact IBU's. I can understand the former because it's just a matter of the amount of fermentables in the water, so the end result is the same whether you had a full boil or a small boil with top-off. But why does the hop utilization change with the boil size? I would assume that the bitterness and aroma would diffuse through the wort in the same manner as the fermentables, no?
     
  2. LarryBrewer

    LarryBrewer Active Member

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    We use Tinseth and Rager equations - developed by scientists.

    Their research found the relationship between hop utilization and boil gravity is non linear. Think about the density of sugar in solution and all the molecules banging around in the wort. The more sugar molecules there are, the less room there is for the hop acids to convert. A super sweet solution would inhibit alpha acid conversion, while a fairly dilute sugar solution would allow more conversion. The sugar is literally getting in the way of the acid conversion reaction in the wort. At least, as the theory, the data, and the equations suggest.

    In forums like HBT, there have been mentions that this is not the actual case, but no one has stepped up and provided solid research on the matter.
     
  3. EvanAltman36

    EvanAltman36 New Member

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    In the online research I've done, it seems like there are differing points of view on the subject, all of which reference materials and research to back up their point. I read one interesting post in which someone claims to have done 2 separate boils with different gravity but the same hop schedule, and that they yielded identical results in aroma a bitterness. I find this hard to believe, as all the calculators out there point to this not being the case in standard practice. I hadn't really concerned myself with it before, but then realized that I had built my recipes based on a smaller boil size and then had to tinker with my hop additions when I changed the boil size. In the end, I decreased the hop amounts, as I'd rather go with what the calculator says than to end up with a Hopslam that I can't share with anyone. It's an interesting topic, but after reading more, it does seem to make sense that a higher-gravity wort would make for poorer AA extraction. However, much of what I've read seems to indicate that it's not actually the gravity that impacts the extraction. In the end, I suppose I'll look at it like actual gravity: it's still a theory and does not actually have a proof, but it works, so why question it. I'll let those who are smarter than me create the tools and I'll use them without worrying about the "why" and I'll just enjoy the end result.
     
  4. LarryBrewer

    LarryBrewer Active Member

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    Yeah, some one needs to step up and do additional studies. We can easily add in a new IBU calculator equation down the road. An anecdotal experiment with an n of 2 in an online forum means very little. There is bitterness as raw IBU, but what really matters is perceived bitterness because that is how it tastes. That's what I wish the calculator could tell us eventually.
     
  5. EvanAltman36

    EvanAltman36 New Member

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    I have the solution: everyone can brew two separate batches of differing wort gravity and identical hops schedules and must then present a bottle of each to me for a perceived bitterness test. I will then report the results. Problem solved.
     
  6. LarryBrewer

    LarryBrewer Active Member

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    The Altman equation! Mail and wait 4-6 weeks for results. :lol:
     
  7. EvanAltman36

    EvanAltman36 New Member

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    I am working on patent and copyright immediately!
     

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