If I boil 25g of hops with an AA of 10 in 5 litres of water for 60 minutes, would this be twice as bitter than if I had used 10 litres of water, or put another way, does a certain amount of hops boiled for 60 minutes half its bitterness every time you double the liquid content.
Bitterness
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Oneiroi
Well-Known Member
Yup, for water definitely, and this should be true for wort as well, as long as the OG is the same at both volumes.
Because OG affects how effectively IBUs are extracted from hops, if your two volumes have different OGs (say because the larger volume is made by topping off the smaller wort volume with water) then it won't be true. In the case of topping off with water, the bitterness will be less than half of what a full boil would produce because of the decrease in utilisation.
To use your example of 25g of 10%AA hops boiled for 60 minutes you would get the following theoretical IBUs at different end volumes:
10l water - 100 IBU
20l water - 50 IBU
10l 1.050 wort - 72 IBU
20l 1.050 wort- 36 IBU
As you said, double the volume = half the IBUs. But...
10l 1.100 wort - 52 IBU
So if you topped it off to 20l with pure water, you'd end up with 20l of 1.050 wort but it would only be at 26 IBU compared to the 36 if you boiled the full 20 litres at 1.050.
Hope that makes sense, I may have just gone and answered a question you weren't actually asking aunsure....
You can always have a play around with something like brewers friend recipe calculator to test out, but it's worth remembering that the formulas we use in home brewing aren't always particularly accurate...
Because OG affects how effectively IBUs are extracted from hops, if your two volumes have different OGs (say because the larger volume is made by topping off the smaller wort volume with water) then it won't be true. In the case of topping off with water, the bitterness will be less than half of what a full boil would produce because of the decrease in utilisation.
To use your example of 25g of 10%AA hops boiled for 60 minutes you would get the following theoretical IBUs at different end volumes:
10l water - 100 IBU
20l water - 50 IBU
10l 1.050 wort - 72 IBU
20l 1.050 wort- 36 IBU
As you said, double the volume = half the IBUs. But...
10l 1.100 wort - 52 IBU
So if you topped it off to 20l with pure water, you'd end up with 20l of 1.050 wort but it would only be at 26 IBU compared to the 36 if you boiled the full 20 litres at 1.050.
Hope that makes sense, I may have just gone and answered a question you weren't actually asking aunsure....
You can always have a play around with something like brewers friend recipe calculator to test out, but it's worth remembering that the formulas we use in home brewing aren't always particularly accurate...
