Hop utilization

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z987k

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Uh... this old thing dies really freaking hard.

From the BJCP exam guide:

BJCP said:
The relationship between the quantity of hops used and the IBU level depends on many factors: length of the boil, wort gravity, vigor of the boil, wort pH, age/condition of hops, hop form (whole, plugs, or pellets), hopping rate, plus several other less important elements.
Come on! Wort gravity has no direct relationship with hop utilization! It works out a lot of the time(so does guessing it won't rain tomorrow without looking at a weather map), but shows a complete lack of understanding of what is going on.
 

david_42

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Interesting that they don't mention this factor: the more hops you toss in the boil, the poorer the utilization.

 

Zamial

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I would try to argue that wort gravity DOES affect the hop utilization...just not very much...

Simply by the fact that water can only absorb so much of the hops qualities. We know this because boiling 3 gallons of water for 60 min. with Hop X then top it off with 2.5 gallons = IBU of X. Now boil the same hops for the same amount of time in 5.5 gallons of water and the IBU will be different and should be higher in contrast.

Being that wort has "things already in the water" the utilization would be lower. It may be able to be measured but probably not much as for taste. The difference would be minor but still present.

Remember, 100% water still has a hydro reading...

or am I waaaaaay off here?
 

Bmorebrew

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Zamial just beat me to it I see - but here WAS my interpretation. Chemically speaking, wort gravity does have a direct impact on the hop utilization. Here is why:

As we know, the specific gravity of wort is higher than that of water because it has sugars dissolved in it. Most things dissolve in water - even things that "don't" dissolve in water, like oil, or methylene chloride, still dissolve in water to some very small degree. This is the nature of water. Everything has a different level of solubility. Think of it this way: there is 'space' in the water for certain things to dissolve, like sugar for example.

So dissolving sugar into water leaves less room for other things to dissolve, like alpha acids for example. So the higher gravity the wort, the less able it is to further dissolve things, especially larger or nonpolar molecules like those found in hops.

Check this guy's work out:
http://www.realbeer.com/hops/research.html

Again, this is all speaking technically, I don't imagine that the homebrewer will ever find this particular factor too noticeable - but I do imagine the big guys like SAB do - same as efficiency. A 1.3% difference in efficiency is meaningless to you or me, but can translate to thousands of dollars for the megabrewers.
 

Yooper

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According to John Palmer's new research, the wort gravity does NOT have a significant impact on hops utilization.

However, break matterial DOES. In a nutshell, all of the break material in the wort can "hold" some of the isomerized hops oils and reduce the utilization.

So, it's not the SG of the wort at all. He said that he was wrong when he wrote the it did. He was correct that the hops utilization suffered, but not for the reasons he first stated.

As Z mentioned, though, the calculators in Beersmith and other programs that figure it by wort gravity are close enough most of the time.
 

Ouroboros

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According to John Palmer's new research, the wort gravity does NOT have a significant impact on hops utilization.

However, break matterial DOES. In a nutshell, all of the break material in the wort can "hold" some of the isomerized hops oils and reduce the utilization.
Makes sense. Are certain grains known for generating more break material than others?
 

Ouroboros

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Interesting that they don't mention this factor: the more hops you toss in the boil, the poorer the utilization.

It looks like the overall decline in cohumulone utilization wouldn't be significant, but I bet the humulone+adhumulone group is. Just wondering, why are those two combined? And where did that graphic originally come from?
 

Bmorebrew

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I would like to see the source of the graph as well - if I read it clearly, the greater the concentration of alpha acids the less utilization you will get from further additions. If this interpretation is correct it makes sense chemically, but I'm not sure why the concentrations are so low.

What I mean is at a concentration of about 55 parts per million of cohumulone we have a 35% utilization. This is only one compound, but how many are there? For bittering hops we are talking about alpha acids at least in the 5% ballpark, which is 50,000 parts per million. If there were five different alpha acids, each at about 1%, or 10,000 ppm, would that not put us at 0.55% utilization? Anybody have distribution coefficient data for hop acids and oils?

Is it like brewhouse efficiency where we measure according to a maximum theoretical yield?

I see that somewhere my brewing science is terribly lacking.
 

Scimmia

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I would like to see the source of the graph as well - if I read it clearly, the greater the concentration of alpha acids the less utilization you will get from further additions. If this interpretation is correct it makes sense chemically, but I'm not sure why the concentrations are so low.

What I mean is at a concentration of about 55 parts per million of cohumulone we have a 35% utilization. This is only one compound, but how many are there? For bittering hops we are talking about alpha acids at least in the 5% ballpark, which is 50,000 parts per million. If there were five different alpha acids, each at about 1%, or 10,000 ppm, would that not put us at 0.55% utilization? Anybody have distribution coefficient data for hop acids and oils?

Is it like brewhouse efficiency where we measure according to a maximum theoretical yield?

I see that somewhere my brewing science is terribly lacking.
You're confusing percent alpha acids in the hops with alpha acids in the kettle, which is what that graph is showing. 1 IBU is roughly 1 PPM of alpha acids in solution.
 

Bmorebrew

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So then only a very small amount of the available alpha acids are actually extracted into the wort? (Wow that was a lot of a's)
 

homebrewer_99

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So, what you're saying is those of us who believe wort gravity DOES affect hop utilization should just stay out of these debates???? :D;)

All I know is I am going to continue all the practices what work for me...:ban::mug:



Scimmia: When are we going to get together and share some brews? I'm still working at the arsenal for 2 more weeks. I have a nice amber ready to drink.
 

Ouroboros

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So, what you're saying is those of us who believe wort gravity DOES affect hop utilization should just stay out of these debates????
Why exactly is there a debate? From what I've read here and elsewhere, it seems like both sides are "right" so to speak. Iso-alpha acids adsorb to break material, and more break material is generated in higher gravity wort. So there is a correlation between wort gravity and hop utilization, but increased gravity is not directly causing a decrease in hop utilization...
 

Scimmia

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So then only a very small amount of the available alpha acids are actually extracted into the wort? (Wow that was a lot of a's)
I wouldn't say very small, that's what the percentages on the Y axis of the graph are. The graph says that as the concentration of alpha acids in the wort go up, the percentage of alpha acids extracted goes down. It is interesting that the utilization of cohumulone is higher than the other alpha acids, I've never heard that before.

homebrewer_99, my pipeline is rather weak right now, but I do have an oatmeal stout that I like. The others that I have were experiments that didn't turn out. What were you thinking?
 

david_42

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The graph is from a paper for OSU's Fermentation Sciences Dept.

Interesting that Glenn's data fit shows utilization dropping faster with OG than Palmer's data from the 2nd edition. Hardly supports the idea that gravity doesn't matter.
 

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jkarp

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James over at Basic Brewing (in conjunction with Chris at BYO) recently did some extract beer experiments where they compared partial and full boil worts and had the resultant beers lab tested. No difference at all in hop utilization, just as the new science Palmer reported said.

Thing is, brewers are a superstitious lot and it will take years for them to come around, just like it did on the aluminum pot myths.
 

Scimmia

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My retirement luncheon is next Thursday at the 11th St. Precinct in the village if you're interested in joining...
I'll have to see what I can do. I actually work up in DeWitt, so getting down there may or may not be possible.
 

SumnerH

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James over at Basic Brewing (in conjunction with Chris at BYO) recently did some extract beer experiments where they compared partial and full boil worts and had the resultant beers lab tested. No difference at all in hop utilization, just as the new science Palmer reported said.

Thing is, brewers are a superstitious lot and it will take years for them to come around, just like it did on the aluminum pot myths.
The thing is, it's not actually new science--it may be new to home brewers. But in one of his interviews since attending the symposium, Palmer talked about the reaction of commercial brewers as being kind of confused and surprised that anyone would think that gravity would have an effect on hops utilization.

The commercial brewing literature is apparently littered with this information, going back decades. e.g. the American Society of Brewing Chemists in 1989:
http://www.asbcnet.org/journal/abstracts/backissues/47-14.htm says
"In the range 10.5-13.5° P, no relationship between hop utilization and original gravity was found. "
 
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z987k

z987k

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Why exactly is there a debate? From what I've read here and elsewhere, it seems like both sides are "right" so to speak. Iso-alpha acids adsorb to break material, and more break material is generated in higher gravity wort. So there is a correlation between wort gravity and hop utilization, but increased gravity is not directly causing a decrease in hop utilization...
This.

This is exactly it.

Gravity itself doesn't matter. A wheat or rye beer with slightly lower OG should show a lower hop utilization than a all barley beer of slightly higher gravity.

Gravity is just mostly required to have a large amount of precipitants. So there is a correlation between Gravity and break material, but the cause of loss of utilization is from the break material not the sugar.
The Gravity and utilization are correlated, but it is not gravity that causes it. Correlation != causation.
 

jkarp

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The Gravity and utilization are correlated, but it is not gravity that causes it. Correlation != causation.
Except in the case of extract brewing where there isn't even correlation, as they found on BB.
 
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z987k

z987k

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Right, which magnifies the issue I think. The old thought that "full boils" with extract would get better hop utilization is incorrect.
 

Ouroboros

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Right, which magnifies the issue I think. The old thought that "full boils" with extract would get better hop utilization is incorrect.
It may not impact utilization, but a partial boil might limit the maximum IBU's you can achieve in your brew. I think I read somewhere that the iso-alpha acid content of some of the stronger IIPA's approaches the solubility limit. If that's true, you might not be able to brew very bitter beers with a partial boil.

If you're only boiling (and hopping) half of your final volume, your final brew can be no more than half-saturated with iso-alpha acids. Unless you do some sort of workaround like adding hops when you boil the water that you're going to be adding the wort to.

As an anecdote, I did soomething along those lines with an IPA before I got myself a stainless 30 qt brew kettle and had good results as far as bitterness goes. Just bottled it and I drank a glass green and flat :cross: I was pretty good on Franziskaner by that point... it seemed like a great idea at the time. I swear my farts smelled like Citra hops today.
 

davesrose

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It may not impact utilization, but a partial boil might limit the maximum IBU's you can achieve in your brew.
This is also what I was thinking. It isn't just wort gravity persay, but wort volume utilzation......I haven't done any tests myself (as I went from extract to AG directly), but from what I've read/ determined, boil volume does have an impact on hop utilization.
 

jkarp

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It may not impact utilization, but a partial boil might limit the maximum IBU's you can achieve in your brew. I think I read somewhere that the iso-alpha acid content of some of the stronger IIPA's approaches the solubility limit. If that's true, you might not be able to brew very bitter beers with a partial boil.

The BYO / BB experiments proved this untrue, or at very least that the max solubility of AA in wort is much higher than everyone thinks. Their experiment beer was a high-IBU IPA. Partial boil made no difference at all.
 

AnOldUR

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James over at Basic Brewing (in conjunction with Chris at BYO) recently did some extract beer experiments where they compared partial and full boil worts and had the resultant beers lab tested. No difference at all in hop utilization, just as the new science Palmer reported said.
This experiment being done with extract is not valid for AG brewers and can be misleading. The same effects of break material are not present when using extract.

Gravities effect on hop utilization (for AG brewers) is similar to its effect on ABV. Higher ABV comes from attenuation not the actual gravity, but few would argue that higher gravity beers generally produce more alcohol.
 

jkarp

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This experiment being done with extract is not valid for AG brewers and can be misleading. The same effects of break material are not present when using extract.
Yes. This has already been said several times in the thread.

Gravities effect on hop utilization (for AG brewers) is similar to its effect on ABV. Higher ABV comes from attenuation not the actual gravity, but few would argue that higher gravity beers generally produce more alcohol.
I'm not sure what you're trying to say here.
 

AnOldUR

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Yes. This has already been said several times in the thread.
Thank-you for pointing out my failure to read every entry (in a thread containing posters making lunch dates) before I made a comment. So sorry. :eek:


And also sorry if my metaphor became mixed. Double :eek:
 
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z987k

z987k

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It may not impact utilization, but a partial boil might limit the maximum IBU's you can achieve in your brew. I think I read somewhere that the iso-alpha acid content of some of the stronger IIPA's approaches the solubility limit. If that's true, you might not be able to brew very bitter beers with a partial boil.

If you're only boiling (and hopping) half of your final volume, your final brew can be no more than half-saturated with iso-alpha acids. Unless you do some sort of workaround like adding hops when you boil the water that you're going to be adding the wort to.

As an anecdote, I did soomething along those lines with an IPA before I got myself a stainless 30 qt brew kettle and had good results as far as bitterness goes. Just bottled it and I drank a glass green and flat :cross: I was pretty good on Franziskaner by that point... it seemed like a great idea at the time. I swear my farts smelled like Citra hops today.
You're right, you'd have saturation point issues on IIPAs...(1 beer style) I would think, but I can't, off the top of my head, think of any factual evidence to back this up but an assumption.
 

Ouroboros

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The BYO / BB experiments proved this untrue, or at very least that the max solubility of AA in wort is much higher than everyone thinks. Their experiment beer was a high-IBU IPA. Partial boil made no difference at all.
Cool... like I said... I just read it somewhere that very bitter IIPA's were nearly saturated. Nice to see people addressing these questions experimentally.
 

SumnerH

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Cool... like I said... I just read it somewhere that very bitter IIPA's were nearly saturated. Nice to see people addressing these questions experimentally.
Their experiments were on a 66 IBU beer (or close to that--definitely in the 60-70 range). Dealing with higher levels was one of the things they discussed and were planning on addressing with future tests. I'm not aware of anyone else addressing it with controlled tests, but would love any links.
 
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