Hops utilization question

OHIOSTEVE · 02-06-2010, 08:47 PM

I have been playing around trying to make my own recipe on beer calculus... when I use a larger boil volume the bitterness goes through the roof.. why do ou get so much more bitterness with the same batch size but a larger boil? Meaning if I boil 3 gallons then top up to 5 gallons I get like 32 IBU...same recipe but a 6.5 gallon boil is over twice the UBU's?

Netflyer · 02-06-2010, 10:43 PM

Quote:

Originally Posted by OHIOSTEVE

I have been playing around trying to make my own recipe on beer calculus... when I use a larger boil volume the bitterness goes through the roof.. why do ou get so much more bitterness with the same batch size but a larger boil? Meaning if I boil 3 gallons then top up to 5 gallons I get like 32 IBU...same recipe but a 6.5 gallon boil is over twice the UBU's?

More water gets greater hops utilization. The amount of water you used was all exposed to the hops during the boil... to get your volume up you added water that was not hopped so less IBU's. The cool thing is if you get a bigger kettle you can do full boils and spend less money on hops

**ajf** · 02-06-2010, 11:27 PM

Quote:

Originally Posted by Netflyer

The cool thing is if you get a bigger kettle you can do full boils and spend less money on hops

Less on hops, but more on boiling.

You could also save hops by starting the boil with only about 25% of the extract, and adding the other 75% with about 15 minutes left in the boil

-a.

dcp27 · 02-07-2010, 12:50 AM

a larger boil means lower wort OG, and hop utilization is mainly a factor of wort OG (not batch OG) and time.

edit: if you want to know more details, you can read this: http://www.howtobrew.com/section1/chapter5-5.html

wyzazz · 02-07-2010, 01:09 AM

Yep, full volume boils or late extract addition will greatly affect your hop utilization.

Netflyer · 02-07-2010, 11:05 AM

Quote:

Originally Posted by ajf

Less on hops, but more on boiling.

Brilliant! I forgot about the extra energy...

Arkador · 02-07-2010, 11:41 AM

it isn't really a matter of volume of water, but maltiness.
a 1.10 boil will get lower utilization than a 1.050 boil if all other factors are the same.
If you want to get more exact numbers, get a brew software like Brewsmith. It will calculate everything out to get you the exact number of IBUs you are looking for.

**jkarp** · 02-07-2010, 12:01 PM

Looks like lots of you are behind on your hop science. Wort gravity has no direct correlation with hop utilization. Isomerization happens just as well in a high-gravity wort as a low one. What does impact utilization is precipitates like hot break and yeast which can carry iso-alpha acids out of solution.

wyzazz · 02-07-2010, 12:07 PM

@jkarp, have any sources you could quote for that? You've piqued my interest...

**jkarp** · 02-07-2010, 01:14 PM

Do some searches here - there's been tons of discussion on it. First mention I'm aware of was from John Palmer on Basic Brewing's March 20th, 2008 episode. I believe someone here recently posted a link to the research paper from the same conference.