Jump to content



Photo
- - - - -

IBU calcs when doing partial mash, & adding extract late.


  • Please log in to reply
6 replies to this topic

#1 RisRah

RisRah

    Kit Master

  • Members
  • PipPip
  • 22 posts
  • Joined 11-April 10

Posted 04 May 2017 - 08:30 PM

Hi guys,
Long term lurker and knowledge vacuum, first real post.

I am a partial mash brewer, who boils hops, uses some grains and some Dry Malt extract, and im trying to keep my IBUs in check for a NEIPA.
I was using brewers friend online calc to compute my IBUs and found that the IBUs change depending on my boil size.

I get that the translation of hop alpha acid to IBUs depends on the gravity of the wort, however i tend to add my dme in the last few minutes of my hop boil to keep the finished colour light.

A convoluted preamble but, The question is:
Should I remove the dme from the calcs to get a more accurate IBU level?

#2 RisRah

RisRah

    Kit Master

  • Members
  • PipPip
  • 22 posts
  • Joined 11-April 10

Posted 04 May 2017 - 08:32 PM

Some quick stats

2kg pilsner grain
0.5kg golden baked oats
2kg light dme

13g warrior hops @60min

12L boil but DME added at very end of boil
23L final vol into fermenter

#3 RisRah

RisRah

    Kit Master

  • Members
  • PipPip
  • 22 posts
  • Joined 11-April 10

Posted 04 May 2017 - 08:32 PM

Some quick stats

2kg pilsner grain
0.5kg golden baked oats
2kg light dme

13g warrior hops @60min

12L boil but DME added at very end of boil
23L final vol into fermenter

#4 Canumbler

Canumbler

    Kit Master

  • Members
  • PipPip
  • 39 posts
  • Joined 18-December 07

Posted 05 May 2017 - 05:12 AM

The brewersfriend calculator has a tick box for your fermentables, "Late addition" that takes this into account. If you tick it and untick it you'll see your IBU result change.



#5 RdeVjun

RdeVjun

    Beer God

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 2,313 posts
  • Joined 19-January 09
  • Location:Toorbul, QLD

Posted 05 May 2017 - 08:29 AM

Are you finding the actual bitterness as brewed is not to your liking?
Always recommend becoming familiar with your recipator application, understand it's usefulness with your particular equipment and method, but be careful though of falling into the trap of tweaking your recipe to suit your application's stats, not your own perceptions and preferences. I've seen many folk cut themselves to pieces fiddling with a recipe before actually brewing it, when its far more informative and helpful to simply brew it and see how it comes out, then adapt.

#6 Rocker1986

Rocker1986

    Beer God

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 2,000 posts
  • Joined 28-April 12
  • Location:Brisbane, QLD

Posted 05 May 2017 - 12:06 PM

I'd agree with the above. I don't brew partials, I brew AG but I no-chill my batches, and there's all this talk about how the hop additions need to be moved to compensate for the longer time the wort stays hot and blah blah blah...

 

I've brewed a couple of recipes that weren't mine without changing them and they've come out perfectly fine. With my own recipes I've just worked out hop schedules that give me the results I want; I've probably inadvertently compensated for no-chill with them, but it's not something I think about or ever did think about when designing the recipes. I just tried different things until I hit the sweet spot.



#7 klangers

klangers

    Beer God

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 659 posts
  • Joined 10-September 14
  • Location:Sydney

Posted 05 May 2017 - 12:45 PM

The accuracy of your weighing equipment as well as the accuracy of the stated alpha acid %age of the hops is likely to be the weakest link in attaining precision of BU rather than fiddling with calculations.

 

Hops of same breed can vary substantially in their AA%, and is likely to be different than what's on the label if you've had them a while.

 

Which is why I agree with the try-it-out method.