# Hop Utilisation in the Whirlpool



## micblair (15/10/13)

Recently purchased a Blichmann therminator, and I've been somewhat surprised by the amount of additional bitterness I was perceiving in my beers, compared with using an immersion chiller.
Measuring the bitterness using the ASBC International method with a UV-VIS spectrophotometer, on a beer brewed with a 20L Braumeister, with a calculated bitterness of 42 mg/L (42 IBU, OG = 13 degrees plato).
The measured bitterness was 57 mg/L, which is out by 15 BU's from the calculated. This isn't surprising as I used 80 g total of cascade and galaxy in equal proportions in a 15 minute whirlpool/hop stand (final temp. 95C) before sending the wort through a heat exchange. 
The bittereness resulting from a 15 minute whirlpool/hop stand is assumed to be 15 BU's, but what's more interesting is to calculate the utilisation during this period.
To do so, these were my assumptions:
1) All my hop additions up until whirlpool matched (Tinsenth) calculated values 
2) Since two different hop varieties were used, I had to average the alphas, i.e. cascade 8% + galaxy 15%/2 = 11.5% 
Rearranging the formula
Hops reqd, g = (BU, mg/L x brew length, L)/% utilisation x %aa in hops
% utilisation = (BU, mg/L x brew length, L)/ Hops reqd, g x %aa in hops
% utilisation = 15 mg/L x 20 L x 1g/ 80g x 0.115 x 1000 mg = 3.2%


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## micblair (15/10/13)

This number could in fact be higher, as bitterness in wort compared to the finished beer can vary substantially so I'm told. I think for future reference, 5% utilisation wouldn't seem entirely unreasonable, especially if you haven't been accounting for it at all.


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## technobabble66 (16/10/13)

Thanks!!

For a newbie, it's great to have a rough guide in determining IBU impact of whirlpool additions. I'd assume it's all somewhat recipe specific & equipment specific, but at least i've got an indication now as to what my flameout additions will really do to bitterness.


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## Kieren (16/10/13)

micblair said:


> Recently purchased a Blichmann therminator, and I've been somewhat surprised by the amount of additional bitterness I was perceiving in my beers, compared with using an immersion chiller.
> Measuring the bitterness using the ASBC International method with a UV-VIS spectrophotometer, on a beer brewed with a 20L Braumeister, with a calculated bitterness of 42 mg/L (42 IBU, OG = 13 degrees plato).
> The measured bitterness was 57 mg/L, which is out by 15 BU's from the calculated. This isn't surprising as I used 80 g total of cascade and galaxy in equal proportions in a 15 minute whirlpool/hop stand (final temp. 95C) before sending the wort through a heat exchange.
> The bittereness resulting from a 15 minute whirlpool/hop stand is assumed to be 15 BU's, but what's more interesting is to calculate the utilisation during this period.
> ...


Have you had the same beer minus the whirlpool hops tested for as well to see how it compares to the calculated target?


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## syl (16/10/13)

Utilisation is normally taken at 10-15% for a hop stand/whirlpool. But that is on pro equipment with a whirlpool tank.

I calculate at 10% utilisation and adjust my recipes according dependent on SG.

So in my recent Pacific Ale clone recipe I wanted 22 IBU from a hop stand - calc'd at 10% util (as I don't have a spectrometer) which is around a 12 minute addition. At 14% AA I needed 1.5g/L to reach the desired level (simply used beer smith and registered it as a 12m addition)

Since you have a spectrometer I would be very interested to see the utilisation of a hop stand only hopped beer or in lieu of that - at least the same beer sans hop stand.

EDIT: Also - where'd you get a Spectrometer? Expensive? Or do you have access to one for work or school?


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## Yob (16/10/13)

I can see a lot of us turning up at Mic's place with bottles in hand


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## slash22000 (16/10/13)

I do the same as Syl. I add +12 minutes boil to every calculated addition for a beer I'm hop standing (12 minutes boil for the hop stand, 42 minutes for a 30 minute addition, 72 minutes for a 60 minute addition etc). Seems to work out. I'm sure it's not exactly what I've calculated but it's close enough I can't really tell the difference, probably within 5 IBU or so.


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## syl (16/10/13)

slash22000 said:


> I do the same as Syl. I add +12 minutes boil to every calculated addition for a beer I'm hop standing (12 minutes boil for the hop stand, 42 minutes for a 30 minute addition, 72 minutes for a 60 minute addition etc). Seems to work out. I'm sure it's not exactly what I've calculated but it's close enough I can't really tell the difference, probably within 5 IBU or so.


I am want to know how micblair has the ability to test it!

If I could get a bit of kit under $300 I probably would.


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## treefiddy (16/10/13)

If you buy me some isooctane I can do it for you (I checked, we don't have any)


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## syl (16/10/13)

treefiddy said:


> If you buy me some isooctane I can do it for you (I checked, we don't have any)


I wouldn't even know where to begin...


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## treefiddy (16/10/13)

My bad, I thought I saw some on special at Aldi the other day


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## drsmurto (16/10/13)

Kieren said:


> Have you had the same beer minus the whirlpool hops tested for as well to see how it compares to the calculated target?


I'd also like to see that the OP has actually tested the same beer before whirlpool. Otherwise this is a single data point with nothing to compare to.


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## DJ_L3ThAL (16/10/13)

/flame suit on

Is a hop "stand" meaning you are not chilling straight after the boil and thus the hops will have extra time (whirlpool time) whilst hot? That is separate to the extra IBUs factored in for no chilling or is it a proportion of that?

/flame suit off


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## slash22000 (16/10/13)

DJ, yes, that's what it means. Instead of chilling ASAP after flame out you give the hops time to steep at sub-boiling temperatures for a period of time, normally around 20 - 30 minutes.


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## micblair (16/10/13)

DrSmurto said:


> I'd also like to see that the OP has actually tested the same beer before whirlpool. Otherwise this is a single data point with nothing to compare to.


It's probably best to think of this exercise as the utilisation error for calculated vs. observed, which would be 1- 42/57 x 100 = 26%, rather than the absolute utilisation on every 20L braumeister for a 15 minute hop stand. As I mentioned, utilisation can't necessarily be inferred from the measured bitterness of beer (cf. wort). So in this case, I agree with comments around measurements for a 60 minute bittering addition. The other thing worth pointing out is this is the utilisation for this recipe, on my system, and my water profile for a 15 minute hop stand at 95C.


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## micblair (16/10/13)

slash22000 said:


> DJ, yes, that's what it means. Instead of chilling ASAP after flame out you give the hops time to steep at sub-boiling temperatures for a period of time, normally around 20 - 30 minutes.


The hop stand is really out of necessity for preventing hot break/hop material entering the heat exchange, over any added flavour aroma -- which i get as a bonus (+ extra bitterness as a trade off). If I could get hop cones for every one of my flameout/whirlpool hop additions I would, and just use a hop back with a brief whirlpool period.


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## micblair (16/10/13)

treefiddy said:


> If you buy me some isooctane I can do it for you (I checked, we don't have any)


http://www.merckmillipore.com/australia/chemicals/isooctane/MDA_CHEM-104718/p_Wmub.s1L3dcAAAEW8eEfVhTl?WFSimpleSearch_NameOrID=isooctane&BackButtonText=search+results

Spectro grade is what you want, unless you want to distill or purify your extractive solvent. Also need a centrifuge as the phase split isn't clean between beer/isooctane.


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## micblair (16/10/13)

syl said:


> Utilisation is normally taken at 10-15% for a hop stand/whirlpool. But that is on pro equipment with a whirlpool tank.
> 
> I calculate at 10% utilisation and adjust my recipes according dependent on SG.
> 
> ...


Hey Syl, work has one. Ideally a uv-vis/NIR instrument (i.e Perkin Elmer) would be the ducks, as it would allow simultaneous measurement of bitterness, colour and %ABV. 
I think your suggestion regarding an all whirlpool hopping experiment is an excellent idea. But, since the isomerisation is a kinetic process, utilisation could in theory (and probably is) calculated from measuring a single hop addition (provided complete isomerisation had taken place), then applying the arrhenius equation for all other hop additions in lieu of conducting several single hop measurements at different times in the boil.


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## drsmurto (17/10/13)

It's probably best to think of this exercise as the utilisation error for calculated vs. observed, which would be 1- 42/57 x 100 = 26%, rather than the absolute utilisation on every 20L braumeister for a 15 minute hop stand. As I mentioned, utilisation can't necessarily be inferred from the measured bitterness of beer (cf. wort). So in this case, I agree with comments around measurements for a 60 minute bittering addition. The other thing worth pointing out is this is the utilisation for this recipe, on my system, and my water profile for a 15 minute hop stand at 95C.


You have no zero point. How do you know whether any other beer brewed by you agrees with Beersmith?


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## syl (17/10/13)

micblair said:


> Hey Syl, work has one. Ideally a uv-vis/NIR instrument (i.e Perkin Elmer) would be the ducks, as it would allow simultaneous measurement of bitterness, colour and %ABV.
> I think your suggestion regarding an all whirlpool hopping experiment is an excellent idea. But, since the isomerisation is a kinetic process, utilisation could in theory (and probably is) calculated from measuring a single hop addition (provided complete isomerisation had taken place), then applying the arrhenius equation for all other hop additions in lieu of conducting several single hop measurements at different times in the boil.



Indeed. But do one and come back to me with your utilisation of Galaxy (or any new world high AA% hop) in the Whirlpool anyway! You will get good beer regardless


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## micblair (17/10/13)

This is ongoing project, will report back once I've got pre-whirlpool and post-whirlpool bitter wort analysed. I am glad some of you guys found this information useful, and others with PhD's (or at least I assume you have one Smurto?) recognise the limitations due to the size of the data set, n=1 but also the assumptions I've had to make to arrive at this figure (which I acknowledged upfront). Perhaps this post should have read: "calculated 42 BU's; found 57... go f*cken figure?" and let members draw their own conclusions around utilisation etc. :beerbang:


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## drsmurto (17/10/13)

I'm interested in the results which is why I asked about the amount of data you have. Yes, PhD in chemistry (synthetic) which is why I find discussions related to hop utilisation, specifically when it comes to no chill adjustments and whirlpool additions, intriguing. Any calculations need to take in to account the decreasing thermal energy (required for the isomerisation to occur) but more importantly, the poor solubility of alpha acids in wort which will only decrease as the temperature drops. I'm yet to see any calculation take these two factors in to account adequately.

Genuinely interested in the results. Like any good scientist, my view can be changed with evidence.

I use a UV-Vis spectrophotometer regularly at work (actually battling with it today), if I find some spare time I will add this to my list of brewing related experiments.


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## Mardoo (17/10/13)

DrSmurto said:


> ...but more importantly, the poor solubility of alpha acids in wort which will only decrease as the temperature drops. I'm yet to see any calculation take these two factors in to account adequately.



Good Doctor, have you a reference of any sort regarding the topic of alpha acid solubility decreasing as wort temperature drops? I would be very curious to engage in further reading on this subject in particular.


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## micblair (18/10/13)

Just tested another 2 batches of beer (and hope to test another this arvo).

Pils, calculated: 32; found 34 (25 g of Riwaka, 5.7% aa and 25g of Nelson, 12.5% aa in the whirlpool).
English Ordinary: calculated 22; found 19 (15 g of EKG, 5.5% aa and 15 g of Riwaka, 5.7% aa in the whirlpool).

_Note_: Calculated (Tinsenth) values are ignoring bitterness contribution from a whirlpool bittering addition. 

Will be interested in seeing just how much bitterness is lost post fermentation for future batches, to get a proper sense of utilisation.


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## NewtownClown (18/10/13)

Mardoo said:


> Good Doctor, have you a reference of any sort regarding the topic of alpha acid solubility decreasing as wort temperature drops? I would be very curious to engage in further reading on this subject in particular.


 solubility also decreases with less agitation....

Some light reading


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## drsmurto (18/10/13)

Mardoo said:


> Good Doctor, have you a reference of any sort regarding the topic of alpha acid solubility decreasing as wort temperature drops? I would be very curious to engage in further reading on this subject in particular.


Malting and Brewing Science by D. E. Briggs, R. Stevens, J.S. Hough and T.W. Young. A bit chewy but has a lot of very good science in it.

Alpha acids are close to insoluble in water. It is the main reason that even after boiling for 60 mins, the amount of isomerisation you achieve is a long way short of 100%. Most calculations rely on numbers between 30 and 40% utilisation. It is what synthetic chemists like me might refer to as the yield of the reaction. 30-40% is a poor yield indicating the reaction is not overly favourable due to the poor solubility of the reactants (alpha acids). If you did the reaction in an organic solvent (which is what a lot of the papers in this area do) then the utilisation increases. Like most chemical reactions it is also affected by temperature. In this case, decrease the temperature and decease the reaction rate.





micblair said:


> Just tested another 2 batches of beer (and hope to test another this arvo).
> 
> Pils, calculated: 32; found 34 (25 g of Riwaka, 5.7% aa and 25g of Nelson, 12.5% aa in the whirlpool).
> English Ordinary: calculated 22; found 19 (15 g of EKG, 5.5% aa and 15 g of Riwaka, 5.7% aa in the whirlpool).
> ...


Interesting to see an increase (slight) in 1 beer and a decrease in another.

Testing wort pre-fermentation and then the resulting beer would also be useful data. Nice work!


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## manticle (18/10/13)

DrSmurto said:


> Malting and Brewing Science by D. E. Briggs, R. Stevens, J.S. Hough and T.W. Young. A bit chewy but has a lot of very good science in it.


And bloody expensive. I have a file of it somewhere (completely legally obtained of course) but would love to get my hands on a hard copy one day.

I'm very interested in your results micblair, particularly as a filthy no chiller who makes no adjustments.


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## drsmurto (18/10/13)

manticle said:


> And bloody expensive. I have a file of it somewhere (completely legally obtained of course) but would love to get my hands on a hard copy one day.
> 
> I'm very interested in your results micblair, particularly as a filthy no chiller who makes no adjustments.


I have the book on my bedside table for when I have trouble sleeping. The library at work has quite a lot of brewing texts.


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## manticle (18/10/13)

That's a good one to have. The Good Mr Butters put me onto it, bless his departed AHB soul.


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## Mardoo (18/10/13)

DrSmurto said:


> Malting and Brewing Science by D. E. Briggs, R. Stevens, J.S. Hough and T.W. Young. A bit chewy but has a lot of very good science in it.


Thanks for your response. I made my way through Briggs' Malts and Malting and unfortunately am waiting on the dosh for M&BS. Eagerly waiting though!


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## slash22000 (18/10/13)

Is there absolutely any moral justification for charging $600+ for a book?


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## DJ_L3ThAL (18/10/13)

slash22000 said:


> Is there absolutely any moral justification for charging $600+ for a book?


Yes. If it has *LOTS *of tits in it. :icon_drool2:


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## krausenhaus (18/10/13)

Would any of you lot with access to spectrophotometers be interested in buying some isooctane and splitting it up so we can all join in?


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## Mardoo (18/10/13)

DJ_L3ThAL said:


> Yes. If it has *LOTS *of tits in it. :icon_drool2:


No tits. Diagrams.


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## Mardoo (18/10/13)

krausenhaus said:


> Would any of you lot with access to spectrophotometers be interested in buying some isooctane and splitting it up so we can all join in?


Shouldn't we be the ones buying it since they're doing the work?

Which brings to mind the brew club I've toyed with trying to round up - BrewLab. Folks dedicated to doing exactly this sort of stuff properly. However Im not sure I need to geek THAT hard at this point in my learning.

Sorry for off topic.


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## micblair (18/10/13)

Ok guys final test is in, and we're getting further away from a triplicate result.

APA, calculated 27, found 52! (30g Nelson 11.1% aa, and 30g Galaxy 12.6% aa in the whirlpool). Yep, utilisation error is around 50%. 

I'm not particularly worried about errors in the range of (+/-) 10% , as the reliability of quantification by UV/VIS compared with HPLC is pretty well documented (and is precisely why commercial breweries don't use it ), but 50% INCREASE is contrary to the losses you would expect to trub and yeast. 

It appears on the face of it, that beers brewed with high aa hops, in particular galaxy, seem to have unexpectedly higher utilisations which is in contradiction with all the publications that I've seen for the kinetic data for isomerisation of the constituents from the family of alpha acids.

Have a good weekend.


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## krausenhaus (18/10/13)

Mardoo said:


> Shouldn't we be the ones buying it since they're doing the work?
> 
> Which brings to mind the brew club I've toyed with trying to round up - BrewLab. Folks dedicated to doing exactly this sort of stuff properly. However Im not sure I need to geek THAT hard at this point in my learning.
> 
> Sorry for off topic.


No, I have access to a spectrophotometer also and was putting the call-out to others with access to a spectro to split some isooctane with me so we can test our beers. I wasn't suggesting that other people go and blow some money on chemicals for the pleasure of analysing my beer samples.


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## micblair (18/10/13)

krausenhaus said:


> Would any of you lot with access to spectrophotometers be interested in buying some isooctane and splitting it up so we can all join in?


Each sample requires 20 mL isooctane and about an equivalent amount for a blank (which you could store and use multiple times in a day). You also need access to a centrifuge, a shaker and various consumables such as disposable pipettes and PPE etc. which add to the cost. The actual labour is 30-40 minutes of an analysts time (I'm a slow and clunky PhD level organic chemist doing this in my spare time), but for this amount of work/testing you could expect to pay around $130-150 commercially.


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## treefiddy (18/10/13)

micblair said:


> Each sample requires 20 mL isooctane and about an equivalent amount for a blank (which you cold store and use multiple times in a day).


So spec/HPLC grade solvent is about $100 a litre, which is $2 per sample. Why do you need to cold store your blank and redo it each time? Just record a baseline and be done with it.


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## micblair (18/10/13)

oops, should say "could". The blank would stay in the instrument reference cell holder for the whole days analysis and prepared fresh each day in a proper analytical lab.


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## krausenhaus (18/10/13)

treefiddy said:


> So spec/HPLC grade solvent is about $100 a litre, which is $2 per sample. Why do you need to cold store your blank and redo it each time? Just record a baseline and be done with it.


I generally blank before reading each sample because the spectro I use is an unreliable piece of shit.




micblair said:


> Each sample requires 20 mL isooctane and about an equivalent amount for a blank (which you could store and use multiple times in a day). You also need access to a centrifuge, a shaker and various consumables such as disposable pipettes and PPE etc. which add to the cost. The actual labour is 30-40 minutes of an analysts time (I'm a slow and clunky PhD level organic chemist doing this in my spare time), but for this amount of work/testing you could expect to pay around $130-150 commercially.


So mix 50/50 wort/isooctane, on shaker for a while, spin down, remove organic fraction and read in spectro?

Is isooctane a commonly used organic solvent? As in, would the chemical stores at your average uni keep it in stock?


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## treefiddy (18/10/13)

That makes more sense. Although ideally you should take the measurement in the same cuvette, unless you're using matched cuvettes. Have you had a go at a commercial beer that you know the IBUs of?

Edit: still learning tapatalk so can't quote, but no it's not a commonly stocked solvent.


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## micblair (19/10/13)

Matched in the sense they are both quartz rectangular cells, with equal transmittance above 200 nm, and with a 1 cm path length (which is all Beer's law cares about). The blank is placed in the reference cell holder and is comprised of an isooctane-octanol solution which I leave in the instrument over the course of the day. Some people just leave the reference cell empty though.


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## treefiddy (24/10/13)

I had a bottle of Pilsner Urquell sitting around that was 3 months past its used by, so I decided to calculate its IBU with an analogous solvent that was in the lab (don't have isooctane).
My prep methods were fairly half arsed, but I calculated an IBU of 37 which is pretty close to the IBU of Pilsner Urquell (~40).

I'll buy a fresh bottle of beer with a known IBU in the next few weeks and give it another go.


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