That is really bloody awesome that you have gone to the effort of doing the research and experimentation and summaried your findings. It seems it has been a big unknown - until maybe now!RelaxedBrewer said:OK, I have done a second draft of the article.
I have included an example brew I did and some example utilisations from different chilling techniques. I also cleaned a few things up.
I understand that this article may go over some peoples heads (most people are not going to understand the maths, I know it took me a little while to get my head around at first). So if you don't want to read the article I will summarise it.
In summary;
1) I have derived an equation that can be used to estimate alpha acid utilisation and therefore IBUs with changing temperatures.
2) This can be used for estimating IBUs from whirlpool/hop stand and no chill additions.
3) This work was an extension of some other peoples work published in per reviewed scientific journals.
4) I have given examples of my no chill technique and the utilisations I expect on my system for different hop additions after flame out.
5) I applied this technique to a big hoppy West Coast IPA style recipe and showed the IBUs I expected from each hop addition.
6) I also have given some examples of utilisations from a few other techniques/systems.
7) I don't have access to equipment to test for alpha acids and there can not get actual IBU values. I am probably going to try to contact a university and see if anyone is interested in this work and try to check with real world values. If this happens we would most likely produce a proper scientific paper.
In the situation you are proposing we are holding the temperature constant and you do not even need most of the work I have done. I have made equations that will work with changing temperatures something that other have not done yet (as far as I am aware).danestead said:@ 90c for 15min I estimate 11.25 IBU's
@ 75c for 15min I estimate 2.25-3.375 IBU's
How does your equation compare and can you show your working so I can later do it myself. Lets assume the temp is kept constant at 90 and 75 deg.
I've been playing around with this and I think you may have made a mistake.RelaxedBrewer said:In the situation you are proposing we are holding the temperature constant and you do not even need most of the work I have done. I have made equations that will work with changing temperatures something that other have not done yet (as far as I am aware).
So for your case we can use existing formula.
To get utilisation we use
U = 1- e^(-kt) (equation 2 in my article).
and k is temperature dependent
k = Ae^(-E/RT) (equation 2 in my article).
The constants A and E/R were solved by experimentation in the second paper I listed (JASKULA, B. KAFARSKI, P AERTS,G. COOMAN, L. A Kinetic Study on the Isomerization of Hop r-Acids J. Agric. Food Chem. 2008, 56, 6408–6415)
and were found to be A=3.13*109 and E/R=11661.
So for your situation all you need to do is plug in the temperature (T), A and E/R into the equation for k.(note: T is in Kelvin)
Then once you have k plug that into the utilisation equation with the time and find U (note t is in seconds).
So for 15 min @ 90C we get U = 7.2%
This equates to an IBU of 8.
and for 15 min @ 75C we get U = 0.8%
This equates to an IBU of 0.8
So your estimates are higher than mine.
I have never used promash, does it give utilisations for hop additions as well as IBUs? The brewing software I have gives 13 IBUs and a 12 U for a 15 min boil (100C) addition of 10AA Citra in 50 OG wort. This is a lot different from what you say Promash is giving you (22.5 IBU). What batch size are you doing and what boil size? (The number I quoted above are for 19L with a 23L pre boil volume)
(The interesting thing that I have done is modify this above method to work with a changing temperature by using some calculus and time series estimations)
Might need to check this Kris. I think for 90mins, U = 3.1%RelaxedBrewer said:...
So for 15 min @ 90C we get U = 7.2%
This equates to an IBU of 8.
and for 15 min @ 75C we get U = 0.8%
This equates to an IBU of 0.8
So your estimates are higher than mine.
I have never used promash, does it give utilisations for hop additions as well as IBUs? The brewing software I have gives 13 IBUs and a 12 U for a 15 min boil (100C) addition of 10AA Citra in 50 OG wort. This is a lot different from what you say Promash is giving you (22.5 IBU). What batch size are you doing and what boil size? (The number I quoted above are for 19L with a 23L pre boil volume)
(The interesting thing that I have done is modify this above method to work with a changing temperature by using some calculus and time series estimations)
After much experimentation with no chill I have basically ended up in this exact scenario. On some lighter beers I only do a whirlpool addition. It feels weird to not boil any hops but it works./// said: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.
Try PM relaxedbrewer. He originally had some small typos to the formulas he wrote up however will be able to help you out via PM to sort out your problem.tateg said:Hi Guys
I am just trying to work the above equations out of curiosity but cant seem to get it going.
for the below scenario can someone tell me the actual equation using the data
So for 15 min @ 90C we get U = 7.2%
This equates to an IBU of 8.
U = 1- e^(-kt) (equation 2 in my article).
and k is temperature dependent
k = Ae^(-E/RT) (equation 2 in my article).
I understand what the values mean just not sure about how to enter them
thanks
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