TAK

Recipes 

I'm brewing an IPA today and was thinking...

i) Hop utilization is positively correlated with the vigor of the boil.
ii) Hop utilization is positively correlated with the volume of the boil.
iii) Boil-off is positively correlated with the vigor of the boil.

Thus, increasing the vigor of the boil will increase the hop utilization, but at the same time as the boil-off continues the hop utilization drops. Since I don't hold full boils I'm wondering, in theory, is it better to keep as vigorous of a boil as possible, or is it better to drop the vigor of the boil and maintain the maximum boil volume?

Denny

Recipes 

I go for vigor for a lot of reasons besides hop utilization. Drive off DMS, increase protein coagulation....

__________________
Life begins at 60....1.060, that is!

www.dennybrew.com

http://www.experimentalbrew.com - the website for the book

TAK

Recipes 

Hmmm, I haven't been brewing very long and have never heard of DMS. Just looked up the wiki, I learn something new every day!

duboman

Recipes 

I agree with Denny, but in reading your post it sounds like you brew extract as you said no full boils? If so and using extract DMS is not a concern and really neither is a very vigorous boil

__________________
Nothing Left to do but smile and drink beer.....

The Commune Brewing Company-Perfecting the "art" of beer since 2010

day_trippr

Recipes 

That implies isomerization is reversed as volume drops. I'm not sure that happens...

Cheers!

phenry

Recipes 

Throw in "rate of" and I think you'll get what I think he means. So in a higher gravity wort, like we're all told, you get a lower rate of utilization. Decreasing your volume faster with a vigorous boil nets you a higher gravity, so in theory less IBUs? I dunno. I don't like to make additions much farther outside 1/4 oz increments, so whatever negligible effects either boil... err, velocity? has on my beer I'm okay with.

__________________
Primary: Singel 2 ; Saison 9
Aging: empty
Lagering: empty
Bottled: RIS ; RIS 2 ; BDSA ; American Stout 3 ; Tripel 3 ; Session IPA 1 ; English IPA 1 ; Session IPA 2
Kegged: Witbier 3

JefeTheVol

Recipes 

i) is correct, but not at a 1:1 ratio

ii) is not necessarily correct. "Positively correlated" means that one variable increases then the other variable increases. I think what you mean is that for any given mass of solute, hop utilization will increase as you dilute the solute. ie increase your water. Having more volume in your boil wont effect hop utilization, utilization is a function of SG not necessarily volume.

iii)Boil-off volume will decrease your utilization more and more through the boil as your volume decreases but only because your gravity increases; and it is not a linear relationship.

Utilization is calculated by 3 functions.
1. Gravity
2. Time
3. Vigor- this one doesnt effect the utilization as much as the other two but it does have an effect. Some people calculate their IBUs without accounting for the vigor of the boil and thats fine; and some people do.

__________________
-Sometimes I feel like I'm up beer creek without a pint glass-

-May the IBU's be with you-

day_trippr

Recipes 

Not really. There's a fundamental issue at play.

And the question at hand remains unanswered...

Cheers!