Hop Utilisation in the Whirlpool

[micblair]

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:

 

[drsmurto]

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.

 

[Mardoo]

...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.

 

[micblair]

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.

 

[NewtownClown]

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

 

[drsmurto]

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.

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.

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!

 

[manticle]

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.

 

[drsmurto]

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.

 

[manticle]

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

 

[Mardoo]

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!

 

[slash22000]

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

 

[DJ_L3ThAL]

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

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

 

[krausenhaus]

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?

 

[Mardoo]

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

No tits. Diagrams.

 

[Mardoo]

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.

 

[micblair]

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.

 

[krausenhaus]

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.

 

[micblair]

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.

 

[treefiddy]

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.

 

[micblair]

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.