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Message |
    
Jack Horzempa
Member
Username: Jack_horzempa
Post Number: 115
Registered: 02-2007
Posted From: 68.82.57.55
| | Posted on Tuesday, October 11, 2011 - 03:16 pm: | 
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I listened to a podcast discussion by John Palmer and Jamil Zainasheff on the topic of Hop Utilization and Water. A link to the podcast is below:
http://thebrewingnetwork.com/shows/719
About a third of the way through the discussion it was stated that recent scientific studies “…measured the amount of alpha (acids) going into solution and it does not depend on wort gravity.”
Does anybody have any papers or other documentation on these scientific studies? Could you provide a link to that documentation (e.g., an article in a trade journal)?
The conventional wisdom was that wort gravity would impact hop utilization (e.g., a partial boil would result is less hop utilization than a full boil for a given bittering hop addition). These scientific studies contradict that conventional wisdom and I would like to read more about this.
Cheers! |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 13286
Registered: 01-2002
Posted From: 24.150.49.181
| | Posted on Tuesday, October 11, 2011 - 03:50 pm: |
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I would welcome more information about this, too. It seems counterintuitive to me that hop utilization is independent of wort gravity. |
Jeff Rankert
Intermediate Member
Username: Hopfenundmalz
Post Number: 345
Registered: 06-2008
Posted From: 76.122.179.76
| | Posted on Tuesday, October 11, 2011 - 04:41 pm: |
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It is not the sugar concentration, but the break material that limits utilization, it you listen. The amount of break material goes up with the gravity. The curves still hold, but the mechanism is different that what was thought.
There was a small mention of this in one of the magazines withing the last year, this old guy can't remember which. |
Denny Conn
Senior Member
Username: Denny
Post Number: 7619
Registered: 01-2001
Posted From: 140.211.82.4
| | Posted on Tuesday, October 11, 2011 - 04:59 pm: |
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Very interesting, Jeff, and intuitively it makes sense. |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 13287
Registered: 01-2002
Posted From: 24.150.49.181
| | Posted on Tuesday, October 11, 2011 - 05:21 pm: |
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Hmmm, that's interesting. It still seems to me that the amount of sugar already in solution would also limit hop utilization somewhat. Perhaps the other factors in iso-alpha acid solubility are so much more important that the sugar really doesn't come into play.
(Message edited by BillPierce on October 11, 2011) |
Jack Horzempa
Member
Username: Jack_horzempa
Post Number: 116
Registered: 02-2007
Posted From: 68.82.57.55
| | Posted on Tuesday, October 11, 2011 - 07:17 pm: |
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As Jeff stated there was a bit of discussion about what might cause lower hop utilization. The statement on the podcast was “The theory at the moment …” and then John and Jamil made mention of hot break (and also so other potential mechanisms). I do not think there are scientific studies which corroborate the theory of ‘more’ hot break being the cause of lower hop utilization. If there are scientific studies in that regard I would be interested in reading those papers as well.
I am hopeful that somebody on the HBD will have references to papers which discuss these matters. |
ChriSto
Advanced Member
Username: Christo
Post Number: 837
Registered: 02-2006
Posted From: 216.176.226.154
| | Posted on Wednesday, October 12, 2011 - 02:32 pm: |
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Weren't the original hop utilization formulae developed based on trial-and-error empirical testing by Rager, et. al. using wort concentration and time of boil as the two primary factors? Based on these two factors (possibly others IDK), resultant IBUs were measured and a corresponding formula was developed (with updated formulae by Tinseth and others that refined the process a bit).
This would suggest that Rager was measuring the wrong thing, but because, I'm assuming, the amount of hot break and the wort concentration are close in proportion, that his findings ended up a close approximation in the end. Interesting indeed. I would like to see the updated testing as well. |
Rob Farrell
Advanced Member
Username: Robf
Post Number: 616
Registered: 02-2003
Posted From: 216.27.76.200
| | Posted on Thursday, October 13, 2011 - 07:27 pm: |
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So foam skimming would improve hop utilization? |
Denny Conn
Senior Member
Username: Denny
Post Number: 7623
Registered: 01-2001
Posted From: 208.85.238.144
| | Posted on Thursday, October 13, 2011 - 09:51 pm: |
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Theoretically, yes. I prefer to do the pragmatic version if it, though, and just wait til the hot break is over before adding hops. Much easier. |
Vance Barnes
Senior Member
Username: Vancebarnes
Post Number: 4219
Registered: 03-2003
Posted From: 76.122.104.54
| | Posted on Saturday, October 15, 2011 - 02:09 am: |
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My typical boil is 90 min but I never add hops until 60 min. Get the hot break out of the way so you get good hop utilization.
But when you consider how things move from higher concentrations to lower it just seems to make sense that hop AA% might be slowed down with higher suger levels. The liquid solvent can only hold so much depending on equilibriams (sp? ha)
(Message edited by vancebarnes on October 15, 2011) |
Jack Horzempa
Member
Username: Jack_horzempa
Post Number: 120
Registered: 02-2007
Posted From: 68.82.57.55
| | Posted on Saturday, October 15, 2011 - 03:43 pm: |
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Vance,
Other folks have also posted that they intuitively think that wort gravity impacts hop utilization. Scientific studies indicate that is not the case. I was sure that somebody that participates on HBD would have references to those scientific study results. I guess I was wrong about that ‘hunch’?
Jack |
Brews and Views Archive 2011 
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