Concentrated boil vs. Full boil

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Ddogsleezy

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Can anybody tell me what the benefits are to doing a full boil rather than just a partial boil. I'm a new brewer and have only done partial boils where I boil 2 gallons and then add water after the boil to reach the 5 gallon mark. Theoretically, this seems like it shouldn't matter to the flavor of the beer but it seems like most serious brewers use the full boil technique. Just curious as to why this is? Thanks.
 

Walker

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I thought about responding to this, but then didn't because it'll probably stir up a ****-storm, but I was listening to a podcast from the brewing network... can't remember who they were talking to... but they said that they had conducted numerous laboratory experiments and had dispelled the myth that higher gravity (like in a partial boil) had an impact on hop utilization.
 

Yooper

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I thought about responding to this, but then didn't because it'll probably stir up a ****-storm, but I was listening to a podcast from the brewing network... can't remember who they were talking to... but they said that they had conducted numerous laboratory experiments and had dispelled the myth that higher gravity (like in a partial boil) had an impact on hop utilization.
Yes, I've even heard John Palmer say he was wrong about that in the past but that he thinks that there is still a difference in utilization, but due to break material in the wort not the SG of the wort like he previously thought.

I will say this- I prefer a full boil. It seems to be less carmell-y, extract-y tasting. Not only that, but for hoppy beers it makes a difference. Not because of the SG of the wort, but because the most IBUs you can get in a wort is right around 100 IBUs, no matter what. They just aren't soluble more than that. So, if you're hoping to make a 75 IBU beer with a 2.5 gallon boil, well you just can't. Because even if you got the max IBUs (100 ish) in a 2.5 gallon boil, once you add 2.5 gallons of water, you've cut them in half. So for an IPA, you really have to do a full boil to get enough IBUs. For most beers, though, that wouldn't be an issue.

Another thing I like is adding the bulk of the extract late in the boil- like near flame out. It seems like the beer tastes less extract-y and more like it should taste. I assume it's because of less maillard reactions, but I don't know that for a fact. I just think boiling extract in a small amount of water tastes a bit carmelly and "thick" to me.
 

Bobby_M

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Right, as far as I can tell, the major impact is dilution of the 100 IBU concentration limit. In other words, as Yooper pointed out, at a 200% concentrated boil, the highest end bitterness at normal dilution is 50 IBU.
 

Walker

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Yes, I've even heard John Palmer say he was wrong about that in the past but that he thinks that there is still a difference in utilization, but due to break material in the wort not the SG of the wort like he previously thought.
Yes, thank you. It was Palmer they were talking to ont he BN. I couldn't remember if it was him or a hop farmer they had on a podcast I also listened to around the same time (would be odd for a hop farmer to tell you to buy less hops, though, eh?)
 

Walker

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the most IBUs you can get in a wort is right around 100 IBUs, no matter what. They just aren't soluble more than that.
Got a link to something here? I've read that the human ability to perceive bitterness maxes out around 100IBU, but I've never heard that you can't get more than that into wort.

I can't wrap my head around it, actually.

What happens if you made 7 gallons of wort at 100IBU and then boil it down to 3 gallons? What happens to the other acids? Where do they go?
 

Yooper

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Got a link to something here? I've read that the human ability to perceive bitterness maxes out around 100IBU, but I've never heard that you can't get more than that into wort.

I can't wrap my head around it, actually.

What happens if you made 7 gallons of wort at 100IBU and then boil it down to 3 gallons? What happens to the other acids? Where do they go?
I can search for a link. I can't remember where I heard it, but I assume it was Palmer- maybe at a NHC.

I'm no scientist, but it has to do with the isomerization of the oils, that only so much can get into the wort before it's saturated. I still do the Pliny clones with 250 IBUs calculated! because there is still tremendous flavor there. But only so much of the hops oils can be isomerized in a certain amount of liquid.

Like I said, I'll search for a link or through some of my notes from NHC.
 
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