Spike Brewing 12.5 Conical Fermenter Giveaway - Enter Now!

Home Brew Forums > Home Brewing Beer > Beginners Beer Brewing Forum > Two Questions - IBU & Half-Boil

Reply
 
LinkBack Thread Tools
Old 12-27-2011, 04:30 PM   #11
Yooper
Ale's What Cures You!
HBT_ADMIN.png
Feedback Score: 0 reviews
 
Yooper's Avatar
Recipes 
 
Join Date: Jun 2006
Location: Upper Michigan
Posts: 60,707
Liked 4364 Times on 3173 Posts
Likes Given: 848

Default

One of the issues with a partial boil and IBUs isn't really related at all to the gravity of the wort and utilization.

BUT, remember that there is a maximum that isomerization can reach (only so much oil can isomerize). The thinking on this is that it's about 100 IBUs, more or less. That of course isn't an issue, as that's about the threshold for the human tongue anyway.

However, when you're doing a partial boil, that means the max IBUs you can get into any beer is limited by the amount of water you add. What I mean is this- say you've got a ton of bittering hops in a 2.5 gallon boil, for 100ish IBUs. When you add 2.5 gallons of water (0 IBUs), that means that your IBUs will be cut in half.

The "cure" to that is to boil as much volume as you can, and lower the amount you top off with.

This isn't usually an issue for most beers, but if you're only boiling 2.5 gallons you'll pretty much be limited to 50 IBUs or so just from dilution.

__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006
Yooper is offline
 
Reply With Quote Quick reply to this message
Old 12-27-2011, 09:15 PM   #12
Oddball
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2011
Location: Montreal, Quebec
Posts: 209
Liked 13 Times on 11 Posts
Likes Given: 2

Default

Quote:
Originally Posted by Brak23 View Post
iBrewMaster on iPad.
Thanks...
__________________
Oddball is offline
 
Reply With Quote Quick reply to this message
Old 12-29-2011, 02:42 PM   #13
Brak23
Feedback Score: 0 reviews
Recipes 
 
Join Date: Feb 2011
Location: Portland, OR
Posts: 174
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by Yooper
One of the issues with a partial boil and IBUs isn't really related at all to the gravity of the wort and utilization.

BUT, remember that there is a maximum that isomerization can reach (only so much oil can isomerize). The thinking on this is that it's about 100 IBUs, more or less. That of course isn't an issue, as that's about the threshold for the human tongue anyway.

However, when you're doing a partial boil, that means the max IBUs you can get into any beer is limited by the amount of water you add. What I mean is this- say you've got a ton of bittering hops in a 2.5 gallon boil, for 100ish IBUs. When you add 2.5 gallons of water (0 IBUs), that means that your IBUs will be cut in half.

The "cure" to that is to boil as much volume as you can, and lower the amount you top off with.

This isn't usually an issue for most beers, but if you're only boiling 2.5 gallons you'll pretty much be limited to 50 IBUs or so just from dilution.
So if I have an electric stove and a 20qt (5 gal) stockpot. What is the max boil I should go for? One beer I had it pretty full (let's say 5 gal). But it never truly boiled. Obviously my next step is to invest in some sort of propane burner. But for now... 3 gal maybe?
__________________
Brak23 is offline
 
Reply With Quote Quick reply to this message
Old 12-29-2011, 02:48 PM   #14
Yooper
Ale's What Cures You!
HBT_ADMIN.png
Feedback Score: 0 reviews
 
Yooper's Avatar
Recipes 
 
Join Date: Jun 2006
Location: Upper Michigan
Posts: 60,707
Liked 4364 Times on 3173 Posts
Likes Given: 848

Default

Quote:
Originally Posted by Brak23 View Post
So if I have an electric stove and a 20qt (5 gal) stockpot. What is the max boil I should go for? One beer I had it pretty full (let's say 5 gal). But it never truly boiled. Obviously my next step is to invest in some sort of propane burner. But for now... 3 gal maybe?
Well, I'd say boil as much as you can. It needs to boil, in a rolling boil, for the 60 minutes. You could add the bulk of the extract late so that you can boil more liquid volume. I'd try the stove with water and see. Start with 2.5 gallons, and bring it to a boil. Add .5 gallon and see if you can still maintain a boil. If you can, add a little more. Then you'll know the max your stove can boil.
__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006
Yooper is offline
 
Reply With Quote Quick reply to this message
Old 12-29-2011, 03:04 PM   #15
Brak23
Feedback Score: 0 reviews
Recipes 
 
Join Date: Feb 2011
Location: Portland, OR
Posts: 174
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by Yooper View Post
Well, I'd say boil as much as you can. It needs to boil, in a rolling boil, for the 60 minutes. You could add the bulk of the extract late so that you can boil more liquid volume. I'd try the stove with water and see. Start with 2.5 gallons, and bring it to a boil. Add .5 gallon and see if you can still maintain a boil. If you can, add a little more. Then you'll know the max your stove can boil.
Thank you! You have been super helpful! I'll give it a shot.
__________________
Brak23 is offline
 
Reply With Quote Quick reply to this message
Old 12-29-2011, 06:33 PM   #16
BrewMU
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2011
Location: Columbia, MO
Posts: 516
Liked 7 Times on 7 Posts
Likes Given: 1

Default

The idea that utilization is reduced in a higher gravity boil is based on the fact that soluble compounds will be less so in water that is already partly saturated. In general, this is unassailable and stone cold fact - there is a limit, for a given pressure/temperature state, to the quantity of solubles water can hold. When every polar water molecule is matched up to an oppositely polarized solute (sugar or hop compound) the water is saturated and, with all due respect to John Palmer, won't dissolve anything else. The questions are, how saturated is high gravity wort, and how does solubility drop with gravity? Clearly, given that there are barleywines with OG higher than 1.1, ordinary worts aren't fully saturated, but they will be partially saturated, and without a doubt there will be reduced solubility of hop compounds - the question is, will it be significant and how much added hops will compensate? I've been under the impression that utilization corrections, like the one in Beersmith for example, were based on scholarly research, but I confess I've never dug into the literature. I'd be willing to bet that it's out there.
You should keep in mind that IBUs ARE NOT a measure of perceived bitterness and ONLY take the solution chemistry into account (that's why a heavy, malty, sweet Imperial needs more IBUs to achieve the same perceived bitterness) - your taste buds are the ultimate judge.

__________________
BrewMU is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
An hour and a half to boil water? Grrr JetSmooth Beginners Beer Brewing Forum 13 03-17-2010 05:51 PM
Boil wort in one and a half pot Pascua Beginners Beer Brewing Forum 4 12-12-2009 07:20 PM
Half Batch vs. Full Boil HOP-HEAD Beginners Beer Brewing Forum 6 11-21-2008 02:23 PM
half boil? Fish-man Beginners Beer Brewing Forum 10 11-01-2008 08:32 PM
Why add half extract at boil, half at knockout? rcd Beginners Beer Brewing Forum 20 08-16-2006 09:17 PM