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.
Interesting that they don't mention this factor: the more hops you toss in the boil, the poorer the utilization.
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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?
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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.
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.
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.
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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?
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Pondering: Roggenwein, Irish Red, Another Single-Hop IPA, Roggenbier w/ local wild yeast Primary: Hefeweizen, Nugget Single-Hop IPA, Chamomile Wheat Secondary: Saffron Metheglin Bottled: Belgian Strong Dark, Saffron Wheat, UK Barleywine, Tripel, IIPA
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?
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"I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth."
Pondering: Roggenwein, Irish Red, Another Single-Hop IPA, Roggenbier w/ local wild yeast Primary: Hefeweizen, Nugget Single-Hop IPA, Chamomile Wheat Secondary: Saffron Metheglin Bottled: Belgian Strong Dark, Saffron Wheat, UK Barleywine, Tripel, IIPA
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.
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Hop utilization
Linear Mode
