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Old 10-03-2009, 03:01 AM   #1
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Default "Isomerization" in Hops???

Hey everyone, can you take a look into this thread and let me know what you think about the idea of the volume of water changing the isomerization of hop compounds. I don't see how the volume of water would be able to variably switch around isomers. Maybe someone can help clear this up.

http://www.homebrewtalk.com/f39/partial-boil-vs-full-boil-139704/

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Old 10-03-2009, 03:19 AM   #2
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It is not the volume of water that affects hop utilization, but the concentration of dissolved sugars in that water. Basically hop utilization in the boil (isomerization) is inversely proportional to the gravity of the boil. So a more diluted wort (full boil) increases hop utilization.. A more concentrated wort (partial boil) will require more hops for the same effect.

...or this is my understanding

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Old 10-03-2009, 03:20 AM   #3
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Quote:
Originally Posted by jbbeer View Post
It is not the volume of water that affects hop utilization, but the concentration of dissolved sugars in that water. Basically hop utilization in the boil (isomerization) is inversely proportional to the gravity of the boil. So a more diluted wort (full boil) increases hop utilization.. A more concentrated wort (partial boil) will require more hops for the same effect.

...or this is my understanding
what he said
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Old 10-03-2009, 06:42 PM   #4
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Cool, that makes sense...not to get caught up in the semantics of the issue, but im nearly positive that 'isomerization' does not have the same meaning as "utilization." Isomer refers to molecules with the same atomic contents but either with a different connectivity or structural layout (such as eclipsed or gause). So why are people throwing around the word? Not to be dogmatic about it or anything...

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Old 10-03-2009, 07:03 PM   #5
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The degree of hop acid utilization is proportional to how much of the total amount of acids are isomerized. So they are related, but not equivalent.

Also, on the original topic, I believe it is the concentration of proteins in the wort that affect isomerization/utilization rather than the sugars. I heard this on Brew Strong, and they explained that as the proteins coagulate and drop out of suspension, they take some of the hop acids with them, decreasing the total amount available for isomerization.

-Steve

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Old 10-03-2009, 08:10 PM   #6
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Quote:
Originally Posted by jbbeer View Post
It is not the volume of water that affects hop utilization, but the concentration of dissolved sugars in that water. Basically hop utilization in the boil (isomerization) is inversely proportional to the gravity of the boil. So a more diluted wort (full boil) increases hop utilization.. A more concentrated wort (partial boil) will require more hops for the same effect.
Actually this was disproven a while back. Hop utilization has no direct correlation to wort gravity, but utilization is impacted by break material which carries iso-apha acids out of suspension. John Palmer reported on this a couple years ago.
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Old 10-03-2009, 08:28 PM   #7
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Protein coagulation could trap some of the acid molecules contributing to the bitterness (and heat is a known source of coagulation), but my point is that 'isomerization' does not make sense. You don't "isomerize" a molecule like you "utilize" a molecule. Molecules exist as one isomer or another isomer, some molecules have the ability to have more than 2 isomers based on the general equation # of isomers = 4N+2where N is the number of chiral centers for the molecule. The amount of water or the sugar concentration will not start flipping isomers. I know how the amount of water changes hop utilization...but why is John Palmer making any regards to isomers?

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Old 10-03-2009, 08:37 PM   #8
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It's the isomerization that creates the bitterness-- converting one isomer of a hop acid into another. For a given amount of hop acids in the boil, the percentage that get isomerized is your utilization.

-Steve

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Old 10-03-2009, 09:42 PM   #9
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i just don't see how water and sugars are flipping isomers. Considering the compounds comprising alpha acids are naturally occurring in hops, chances are they are pretty stable. Water is obviously very stable, and sugars are typically very stable. So if we are dealing with 3 relatively low energy molecules without a tendency to be very reactive, even with the input of heat, why would we start changing around the isomers? Also, can anyone find an image of the molecular structure of an alpha acid? This would help solve the issue...if its not a chiral molecule this discussion will change pretty quickly.

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Old 10-03-2009, 09:48 PM   #10
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hmmm i question why i ask all these questions....i love hops :-)

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