Calculation of IBU additions after flame out (no chill/whirlpool)

[RelaxedBrewer]

After a fair bit of reading and playing around I have done some work on how to calculate IBUs after flame out.

Attached is an article outlining what I have done.

Hopefully some of you actually read it and can offer some thoughts.

If anyone has any questions I am happy to answer them.

View attachment nochillwhirlpoolIBUutilizationcalculation1.pdf

 

[RelaxedBrewer]

I forgot to point out that the article is just first draft.

 

[Not For Horses]

I had a read through it. Seems like the maths is pretty solid although it has been a few years since I studied differential calculus.
The numbers seem to follow accepted wisdom which, from what I can gather, is based on empirical evidence.

 

[Alex.Tas]

Thats awesome. Great work, love the application of science and maths! the difference between the lid on and lid off method was far grater than i expected. I reckon the extraction fan was the main culprit, drawing air over the top of your cooling wort.
Thanks heaps for doing this investigation. taking 5 minute readings for 2 hours must have been a pain!

 

[AndrewQLD]

Very interesting read, I would worry about cubing when the temp drops down to 80 c as you will get a further drop in temp on transfer and could run the risk of infection.

 

[RelaxedBrewer]

Very interesting read, I would worry about cubing when the temp drops down to 80 c as you will get a further drop in temp on transfer and could run the risk of infection.

Yeah, I actually brewed yesterday and began the transfer from the kettle to the cube after 22 min of cooling with the lid off. The temperature was still 85C (According to my equation it should have been 86C, so pretty close). I would not recommend transferring at 80C either. I will make my article clearer.

Thats awesome. Great work, love the application of science and maths! the difference between the lid on and lid off method was far grater than i expected. I reckon the extraction fan was the main culprit, drawing air over the top of your cooling wort.
Thanks heaps for doing this investigation. taking 5 minute readings for 2 hours must have been a pain!

Thanks mate, much appreciated. I reckon you are right about the extractor fan.
The 5 min readings were a pain in the ass, but I had a few brews to help and managed to write a fair chunk of the article during it.

 

[///]

The usual software programs used to pretty much ignore the BU's gained from the whirlpool step, so the no-chill isomerisation rates would be out of the picture.

i know what i usually get for the whirlpool step thru testing with a photospectrometer via a pentance absorbance test, it can be up to 80% depending on the amount of BU needed, the gravity and the amount of whirlpool hop added. In our lager we use no bittering hop, and just about to drop out the bittering hop for the ligher golden ale.

My advise to no chill brewers is to remove any 'mid' additions, ie. hops at 15, 10, 5 minutes, and just utilise the whirlpool with a standard amount taken from the step.

Not sure if I would drop the temp and then fill the no-chill container, i would go as hot as possible to maximise the pasteurization units particularly if you are reusing the container.

 

[RelaxedBrewer]

The usual software programs used to pretty much ignore the BU's gained from the whirlpool step, so the no-chill isomerisation rates would be out of the picture.

i know what i usually get for the whirlpool step thru testing with a photospectrometer via a pentance absorbance test, it can be up to 80% depending on the amount of BU needed, the gravity and the amount of whirlpool hop added. In our lager we use no bittering hop, and just about to drop out the bittering hop for the ligher golden ale.

My advise to no chill brewers is to remove any 'mid' additions, ie. hops at 15, 10, 5 minutes, and just utilise the whirlpool with a standard amount taken from the step.

Not sure if I would drop the temp and then fill the no-chill container, i would go as hot as possible to maximise the pasteurization units particularly if you are reusing the container.

You get a utilization of 80%? Or 80% of your IBUs are coming form the whirlpool (I think you must mean the latter).

If you have some actual numbers on IBUs you get from whirlpool with time and temp I would love to see them.

 

[///]

Sorry, i get 80% of the BU's from the whirlpool.

I'll do more testing in a few weeks, but i know from practice;

* Pale ale with 3 grams a litre of whirlpool gives 50% of total BU from whirlpool (mix of mid - low alpha hops)
* IPA with 5 gms a litre whirlpool gives 50% of total BU (using a mix of mid to medium high alpha US hops)
* Golden Ale with 2.5 gms a litre whirlpool gives 80% (using high alpha Aussie hops)

Some of the Aussie hops have alphas into the medium to high teens, so this has a massive impact, as does your gravity. And it is approxmiates as well ... as I said, need to test again.

 

[Online Brewing Supplies]

How long are you w/pooling for before reaching ferment temps and what temp is the initial w/pool ?
Nev

 

[RelaxedBrewer]

Sorry, i get 80% of the BU's from the whirlpool.

I'll do more testing in a few weeks, but i know from practice;

* Pale ale with 3 grams a litre of whirlpool gives 50% of total BU from whirlpool (mix of mid - low alpha hops)
* IPA with 5 gms a litre whirlpool gives 50% of total BU (using a mix of mid to medium high alpha US hops)
* Golden Ale with 2.5 gms a litre whirlpool gives 80% (using high alpha Aussie hops)

Some of the Aussie hops have alphas into the medium to high teens, so this has a massive impact, as does your gravity. And it is approxmiates as well ... as I said, need to test again.

I think you might have missed the point of my article.

I have derived an equation that will let you estimate how many IBUs you will get from your hop additions after flameout (if you know how your system cools) by giving a utilisation for the hop addition. (utilisation is how much of the alpha acids we add to the beer/wort actually ends up as iso-alpha acids for the addition)


If you had understood this, my apologies.

 

[Lord Raja Goomba I]

I've been thinking about whether transferring at high temps into cube but waiting until the cube has cooled to 90 (or 80 or whatever) degrees to cube hop, in order to replicate a shorter isomerisation time (say of a 5 minute chilled addition).

This might help figure that out.

 

[technobabble66]

Hey RB, Great work - totally agree with the hand wavy thing.
Great to see a little science/math to back-up the various suggested estimates. Also good to see the important differentiation of lid on & off!

One minor detail wrt the Area under the Curve graph near the end, and the subsequent U values from it (page 7): i assume the t on the x-axis is for time in minutes, or is it still in seconds (100's)?
And the values for U for Lid On/Off are calculated for what value of t? 25mins?

FWIW, i did a fair bit of reading ~12mo's ago to get a handle on this whirlpool IBU stuff.
Got similarly annoyed by the vagueness of something that seemed vitally important (cf the extremes people went to to justify the whole rehydration debate <_< ).
I eventually found the repeated statements (from some respected/experienced brewers) around the idea of a 20min whirlpool equating to an extra 12mins of boil time, and cubing was the equivalent of an extra 20mins boil time. (so i guess if you whirlpool & cube, the extra 30-35mins calculated gets you a fair way to the 60min equivalent your calculation indicate). As III above stated, it was suggested this varied a fair bit for the higher %AA hops. Sorry, no links to the threads/papers i read to back this hand wavy opinion, though.

PS: the brew i did on the weekend (for the Swap) was a small 20min addition with a rather large Flameout addition (cascade + Nelson), followed by 45mins stand with the lid off and a fan blowing on it to drop the temp. (coincidently i think i checked the temp when i started draining & it was something like 72°C ?). I estimated this as a ~24mins boil equivalent (2x 12mins for a 20min stand + a 20min whirlpool). So it'll be interesting to see how the IBU's appear when it comes to drinking time.

 

[TheWiggman]

Posting in epic thread.

Top work relaxedbrewer, I take it you're not a forkilft driver? And if you are, more credit to you.

What would be unreal is if this simulation could be tested in real life to see how closely the measured bitterness lines up with the calculated bitterness. If the two are close then you could put that calculator on a web page and be guaranteed lots of hits from home brewers around the world. It's certainly making me think about my next approach as a no-chiller with limited batches.

One question I have surrounds the utilisation as a figure in the document. What do the actual utilisation percentages mean in terms of IBU? For example, if I'm targeting 30 IBU and I have a calulated 60 min addition and 5 mins that ends up being 30 for a chilled batch, what do I do to adjust this so that I can acheive the same thing when no-chilling?

ED: More clearly I suppose what I'm trying to say is how would I correlate utilisation with IBU? 5% AA hops x 30% calculated utilisation = ????
ED again - http://www.howtobrew.com/section1/chapter5-5.html should tide me over to the above query. Though it would be nice to include it in your next version of the doc
Also please say 'maths' and not 'math', 'cause I'm 'Strayan.

 

[RelaxedBrewer]

I have done a little more work and a test brew.
Since there seems to be some interest generating I will probably post a 2nd draft in a couple of days that will include some examples of what to expect for different systems as well as my own and a bit of a tidy up.

One minor detail wrt the Area under the Curve graph near the end, and the subsequent U values from it (page 7): i assume the t on the x-axis is for time in minutes, or is it still in seconds (100's)?
And the values for U for Lid On/Off are calculated for what value of t? 25mins?

I am at work at the moment and all my data is at home so will have to check to be 100% sure.
The time is in minutes on the Area under the curve graph. It also looks like the heading should have been for lid off.
U was calculated over 2.5 hrs form memory but would have to check.

What would be unreal is if this simulation could be tested in real life to see how closely the measured bitterness lines up with the calculated bitterness. If the two are close then you could put that calculator on a web page and be guaranteed lots of hits from home brewers around the world. It's certainly making me think about my next approach as a no-chiller with limited batches.

I would love to do this. If /// gets back to me with some details it might be possible.
I have also been considering contacting someone from one of the Universities that does food science related research and seeing if they are interested.

One question I have surrounds the utilisation as a figure in the document. What do the actual utilisation percentages mean in terms of IBU? For example, if I'm targeting 30 IBU and I have a calulated 60 min addition and 5 mins that ends up being 30 for a chilled batch, what do I do to adjust this so that I can acheive the same thing when no-chilling?

ED: More clearly I suppose what I'm trying to say is how would I correlate utilisation with IBU? 5% AA hops x 30% calculated utilisation = ????
ED again - http://www.howtobrew.com/section1/chapter5-5.html should tide me over to the above query. Though it would be nice to include it in your next version of the doc
Also please say 'maths' and not 'math', 'cause I'm 'Strayan.

The brewing software I use lets me add whirlpool hop additions (I assume most do). These whirlpool additions require a utilisation to be entered. The utilisation calculated can be entered into this to give the IBUs.
eg Using my method a flame out whirlpool addition on my system has a U = 13.6%. If we used some high AA hops like 14% AA Galaxy, to get and IBU of 30 from the addition we would need to add ~38g of hops. Does that make sense?
PS. I will correct math to maths for you

 

[RelaxedBrewer]

I've been thinking about whether transferring at high temps into cube but waiting until the cube has cooled to 90 (or 80 or whatever) degrees to cube hop, in order to replicate a shorter isomerisation time (say of a 5 minute chilled addition).

This might help figure that out.

I have been doing something similar and is what triggered this bit of work for me. This should be prefect for what you are doing.

 

[Lord Raja Goomba I]

I have been doing something similar and is what triggered this bit of work for me. This should be prefect for what you are doing.

I suppose you assume the 'lid on' calculations to be about right for cube hopping and immediately transferring and then waiting?

 

[RelaxedBrewer]

I suppose you assume the 'lid on' calculations to be about right for cube hopping and immediately transferring and then waiting?

I did a brew the other day and did.
However, I found that my cube was cooling slightly faster than the 'lid on' did. I think it is because after fill and seal the cube I put it on the concrete floor of my garage. This probably draws a fair bit of the heat out to the floor. I had planned on adding an addition at 75C but it was down to 66C. I am going to have to redo the cooling experiment with my cube and update the article.

I plan on doing something like lid off cooling to 90C (~15min), then fill the cube and cube chill. With this I can have a hop addition at flameout and at 90C easily (and others in between).
There is always the possibility of opening the cube for more additions later but this adds the risk of infection and I only do it if pitching the next day (others will say don't do it at all).

 

[Trevandjo]

After a fair bit of reading and playing around I have done some work on how to calculate IBUs after flame out.

Attached is an article outlining what I have done.

Hopefully some of you actually read it and can offer some thoughts.

If anyone has any questions I am happy to answer them.

I took the option of skipping the maths sections. I did get a bit overwhelmed with some of it.

Great work with the research. I'm soon to begin no chilling so would certainly find a calculator useful.

Thanks
Trev

 

[///]

If you had understood this, my apologies.

Hi - I got that. More so my point is that you can get a heap of utilisation, perhaps more with the difference in cooling times.

This is good stuff to look at, particularly as it relates directly to the brewers here