Armchair Philosophy Re: Hop Utilization

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?

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

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!

Denny said:

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

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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

TAK said:

[...]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.[...]

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

Cheers!

day_trippr said:

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

Cheers!

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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.

TAK said:

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.

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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.

phenry said:

Throw in "rate of" and I think you'll get what I think he means.

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

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.[...]

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And the question at hand remains unanswered...

Cheers!