Believe the calculators for extract? All in IPA recipe

[Matheos]

Hey again guys,

I am planning my fourth recipe atm, but I keep getting stuck on some details. I am new to brewing and therefore, I want to try to explore LME instead of DME this time. I am planning a simple recipe, but the IBU calculations are giving me headaches.

I want to use some X amount of LME (in KG). I only have access to a 10L pot, so I will add 8L of water to my boil. Because of this, I need to calculate how much LME I wanna boil to get a pasteurized wort for my hop additions, and then later on add the remaining LME at flameout.

I had the recipe all done and tidy, but now when I change a large part of my LME to late additions the IBUs go through the roof. Could someone explain this to me, and tell me what to believe?

My recipe (WIP):
19L batch
8L water in the pot
The manufacturer reports 80-82 brix for the LME. I don't understand this number as this translates into massive SG, which recipe calculators can't even take in as the yield is larger than 100%! So Instead, I calculate with 300PKL (36PPG) as some average number for LME.
This gives me the following calculations if I wish to have a pre-boil gravity of around 1.040
LME in boil = (40 points * 8L) / 300PKL = 1,07Kg so about 1Kg.
Fermentables:

1Kg	LME	Boil
2Kg	LME	Flameout/straight to fermentor

Hop additions (a bit unorthodox perhaps but it is all my left over pellets):

Chinook	12,8 AA	55g	Boil	@ 60
Cascade	5,5 AA	10g	Boil	@ 10
Chinook	12,8 AA	10g	Boil	@ 10
Enigma	18,6 AA	36g	Dry hop	3 days
Cascade	5,5 AA	66g	Dry hop	3 days
Chinook	12,8 AA	35g	Dry hop	3 days

Yeast: US-05

Brew father reports this as 114 IBU, Brew target some 90. Is this true? Considering I top of in fermentor to 19L? Or am I missing something. I am aiming for some 35-50 IBUs and perhaps just above 5% abv.

Also, feedback on the recipe overall? As mentioned, I got the hops and these are all I got. The LME is still to be purchased and so is the yeast. So nothing is final except the hops, though their schedule could be altered.

 

[VikeMan]

Here's what's happening. The Tinseth formula specifies a "Bigness" factor that considers the average boil gravity of the wort, because Glenn Tinseth found that higher gravity beers had less measured IBUs.

However, it's not actually the sugars in the wort during the boil that influences the bitterness, but (almost certainly) proteins, yeast (and possibly other compounds) in the wort, which tend to drag isomerized alpha acids out of solution. IMO, it doesn't matter (or doesn't matter much) when the extract containing the proteins is introduced.

Nevertheless, when people discovered late extract additions, they naturally assumed bitterness would be enhanced and made sure the IBU calculators assumed so too.

Personally, for IBU calculation purposes, I would put all the extract in at the beginning of the boil (in the calculator), regardless of when the extract is actually going to be added.

Brew father reports this as 114 IBU, Brew target some 90. Is this true?

No, for the reasons stated above. As an aside, you probably can't get 114 IBUs in a normally brewed finished beer, regardless of the wort gravity and the amount of hops. Also, beware of any IBU predictions above 65 IBUs. Real life utilization curves really start to flatten out above about 65, and standard formulae don't account for that.

Last thought: It isn't clear to me if you're inputting the total batch size (for water volume calculation purposes) into the calculator, but if not, you need to do that.

 

[Matheos]

Here's what's happening. The Tinseth formula specifies a "Bigness" factor that considers the average boil gravity of the wort, because Glenn Tinseth found that higher gravity beers had less measured IBUs.

However, it's not actually the sugars in the wort during the boil that influences the bitterness, but (almost certainly) proteins, yeast (and possibly other compounds) in the wort, which tend to drag isomerized alpha acids out of solution. IMO, it doesn't matter (or doesn't matter much) when the extract containing the proteins is introduced.

Nevertheless, when people discovered late extract additions, they naturally assumed bitterness would be enhanced and made sure the IBU calculators assumed so too.

Personally, for IBU calculation purposes, I would put all the extract in at the beginning of the boil (in the calculator), regardless of when the extract is actually going to be added.



No, for the reasons stated above. As an aside, you probably can't get 114 IBUs in a normally brewed finished beer, regardless of the wort gravity and the amount of hops. Also, beware of any IBU predictions above 65 IBUs. Real life utilization curves really start to flatten out above about 65, and standard formulae don't account for that.

Last thought: It isn't clear to me if you're inputting the total batch size (for water volume calculation purposes) into the calculator, but if not, you need to do that.

Thanks for the reply man. Interesting information! I will change my late additions to all be regular. In Brewtarget which is my main tool, it does not make any difference in terms of IBU though, just for Boil SG which I assume is pre-boil SG. Now Brew target reports 103 (LOL!) IBU with 3kg 82% yield LME. Brewfather makes more sense at 55 now.

Lastly, Whatever calculator I use, I always give 8L preboil volume and then "in fermentor" = batch size. Or in cases where it wants "fermenter top of", I give approximately how much water is needed to top of to 19L after the boil, taking into account boil off. Is this what you meant?