Late extract addition

[Mavy]

Hello,

I created my first recipe with the recipe editor and I have a question regarding the IBU calculations for late extract addition. The total volume of the batch will be 14 litres and the boil volume will be 4 litres. I plan to steep some grains, add a part of the extract in the beginning of the boil, add the hops and the rest of the extracts at the end. If I get this right from the FAQ (http://www.brewersfriend.com/faq/#recipes10) for the IBU calculations to work when the late addition box is checked, I should be adding 50% of the extracts at the beginning of the boil (60-min) and the other 50% at the 10 min mark. Is this correct?

Thank you in advance!

 

[J A]

My understanding is that if the late addition box is checked, the total amount of that extract addition should be added at the 10 minute mark. You can add as much or as little extract as you want at the beginning.
When I want to add part of the extract in the full boil, I just split it and treat it as 2 different ingredients to reflect the amount that's held for late addition. As long as your pre-boil gravity closely matches what's predicted, the IBU's will be pretty accurate.

 

[Mavy]

Thank you, this makes more sense. The IBUs change dramatically when the 'late addition' is checked, so the calculator probably assumes that all the extract is added at 10 min (and counts only the sugars from the specialty grains for the boil). I will split the extracts in two parts and re-do the calculation. Cheers!

 

[J A]

It works really well to weigh and split the extract addition.The other thing that will change things is the efficiency percentage for the steeped grains. If you do a "mini-mash" with base malts you can extract a fair amount of fermentables from the grain. If you're only steeping specialty grains, probably a lot less. The default efficiency is around 35%.
The efficiency setting mostly has a slight impact on OG if you're adding part of your DME/LME to the boil, but if you have a 60 minute boil with just wort from the steeping grains, it can really move the IBU number quite a bit.