I have successfully brewed a partial mash recipe numerous times using a 2 U.S. gallon 'beverage cooler' to create my wort to which I then add 1.4kg of DME . I am now hoping to experiment with some adjustments to my hop bill but think it would make sense to know where I'm starting from in regard to the IBUs. My problem is that I don't know how to use a calculator if my boil is only 11ltrs (gravity about 1.033) but then I'm adding DME for the last 15min and then adding water to the fv to make a total volume of around 19ltrs. I'm assuming that the addition of DME will effect the bitterness but not as much as if it went in at the start of the boil. Advise gratefully received.
Partial Mash IBU confusion
- Thread starter Shepton
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For my partial mashses (I make British light ales, summer ales and bitters) I use 1.5 kg of crushed malt + the full quantity of hops needed for my 21 litre final volume in a 2 gallon stock pot.
DME should only add to the malty-ness. Dilution with water will change the hoppy-ness
I also used to add the DME into the boil, but now I mix the DME in to cold water in the fermenting vessel before adding the wort.
The reason for this is because I could never get a light enough colour when making summer ales. Extra light spray malt would always darken when boiled.
For my partial mashses (I make British light ales, summer ales and bitters) I use 1.5 kg of crushed malt + the full quantity of hops needed for my 21 litre final volume in a 2 gallon stock pot.
DME should only add to the malty-ness. Dilution with water will change the hoppy-ness
I also used to add the DME into the boil, but now I mix the DME in to cold water in the fermenting vessel before adding the wort.
The reason for this is because I could never get a light enough colour when making summer ales. Extra light spray malt would always darken when boiled.
An Ankoù
Landlord.
I think I'd put in the pre boil size at 11, the post boil at 19 and the target ibus for 19 litres. I'd disregard the late addition of DME as that won't affect the utilisation very much.
Generally, you'll need more hops than boiling full volume to hit the target bitterness. But as above, set your pre-boil size to 11L and your OG as the target OG after adding the DME.
I use a method like yourself and now add the DME at the start of the boil, purely for convenience, I haven't noticed any darkening by adding it this early.
I guess you're using something like this as a calculator? Which is what I use. IBU Calculator Beer Bitterness - Brewer's Friend
I use a method like yourself and now add the DME at the start of the boil, purely for convenience, I haven't noticed any darkening by adding it this early.
I guess you're using something like this as a calculator? Which is what I use. IBU Calculator Beer Bitterness - Brewer's Friend
PhilBrew
Landlord.
Hi @Shepton
Most of the time, you can just use brewing calculators and you'll (mostly) get out what the calculator predicts ... but then, every so often, you sort of need to understand how the calculator is coming up with those numbers, to get it to predict the outcome from your process
Some calculators support you doing smaller boils and adding water into the FV ... check your calculator, possibly in your "equipment profile", for ability to specify "post-boil additions" or "FV dilution", and it may well do the sums for you (if you say which calculator(s) you use, someone on here may well know more) ... alternatively, you could just use your calculator to get it to work out your hop additions (separately from calculating OG and colour) to get you 19/11ths of the IBUs that you want in your finished beer, in the boiled portion of your wort ... if you wanted a 35 IBU beer, you'd boil up 11 litres of (35*19/11=) 60.5 IBU wort, to dilute to your 19 lts brewlength ... and since you're only adding your DME for a short time, at the end of the boil, then calculate that bitterness boiling your hops in the wort with the fermentables from only the mashed portion of your wort
Cheers, PhilB
Most of the time, you can just use brewing calculators and you'll (mostly) get out what the calculator predicts ... but then, every so often, you sort of need to understand how the calculator is coming up with those numbers, to get it to predict the outcome from your process
... it helps (I find, and I hope this will help you) to remember that the IBU is defined such that 1 IBU is 1mg of isomerised alpha-acid per litre of wort/beer ... so if you were to make 5 lts of 60 IBU wort, say, and then diluted it down to 10 lts, the resultant wort/beer would have 30 IBU ... and the the other thing you need to understand is that the utilisation (rate of extraction) of the alpha-acids in the hops in the boil is (inversely) proportional to the gravity of the boil (the higher the gravity, the less alpha-acids would be extracted, isomerised and dissolved into the wort, from the same amount of hops).
Some calculators support you doing smaller boils and adding water into the FV ... check your calculator, possibly in your "equipment profile", for ability to specify "post-boil additions" or "FV dilution", and it may well do the sums for you (if you say which calculator(s) you use, someone on here may well know more) ... alternatively, you could just use your calculator to get it to work out your hop additions (separately from calculating OG and colour) to get you 19/11ths of the IBUs that you want in your finished beer, in the boiled portion of your wort ... if you wanted a 35 IBU beer, you'd boil up 11 litres of (35*19/11=) 60.5 IBU wort, to dilute to your 19 lts brewlength ... and since you're only adding your DME for a short time, at the end of the boil, then calculate that bitterness boiling your hops in the wort with the fermentables from only the mashed portion of your wort
Cheers, PhilB
Thanks all for taking the time to reply,
All really helpful info. - Using what PhilBrew has said, I should be able to get a good idea of what my current recipe is giving me in terms of bitterness and then make any tweaks with more of a sense of direction rather than random changes. Cheers!
All really helpful info. - Using what PhilBrew has said, I should be able to get a good idea of what my current recipe is giving me in terms of bitterness and then make any tweaks with more of a sense of direction rather than random changes. Cheers!
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