Hop Utilisation in the Whirlpool

[micblair]

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%

 

[micblair]

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.

 

[technobabble66]

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.

 

[Kieren]

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%

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

 

[syl]

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?

 

[Yob]

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

 

[slash22000]

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.

 

[syl]

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.

 

[treefiddy]

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

 

[syl]

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...

 

[treefiddy]

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

 

[drsmurto]

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.

 

[DJ_L3ThAL]

/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

 

[slash22000]

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.

 

[micblair]

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.

 

[micblair]

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.

 

[micblair]

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.

 

[micblair]

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?

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.

 

[drsmurto]

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?

 

[syl]

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