hop utilization and wort gravity

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Noob_Brewer

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OK, I posted a question in a different thread but thought this would apply to all different kinds of beers, but is the current consensus that hop utilization is NOT affected by wort gravity? Ive read in HBT and other places that while Palmer originally stated that hop utilization goes down with higher wort gravities but that contention doesn't seem to still be supported now.

Fast forward to my situation: Im currently trying my hand at my first double NEIPA and Im trying to determine if I need to increase my overall hop amounts IF hop utilization does indeed go down with higher gravity beers. Also, in beersmith, Ive noticed that a 60minute buttering charge with Columbus has a higher IBU estimation with a previous beer (1.065) compared to the current double I am working on (1.075). The grain bill is the same with the exception that the malts are increased a little bit. So while Im not sure exactly how beer smith is calculating the IBU contribution, it would seem to suggest (in my brain) that beer smith is lowering hop utilization with higher gravities but I could be dead wrong with this idea.

Any thoughts on your experiences on whether hop utilization is affected by wort gravity would be helpful. Trying to determine if I need to up my total hop rates or not for this double I am working on.

Thanks
 

VikeMan

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OK, I posted a question in a different thread but thought this would apply to all different kinds of beers, but is the current consensus that hop utilization is NOT affected by wort gravity?

Hop utilization (IBUs) is definitely affected by wort gravity, or (more precisely) there is a definite correlation between the two. IMO the only thing up for debate is "why?" It's possible (probable IMO) that it's not the actual sugar/dextrin content (i.e. the major gravity drivers), but maybe something else in the wort (protein concentration?) that also correlates with gravity.
 
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Noob_Brewer

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@isomerization thanks for providing this! Ive had a day now to read through it but to be honest, with regards to the relationship between hop utilization and wort gravity, this article is not convincing any more than anecdotal reports in my humble opinion. While I am not a statistician, I am a researcher that is used to writing and reading manuscripts associated with scientific experiments, so here are my two cents - or however much you think it is worth :) - on this issue specific to this article. The article specifically wanted to ask a question related to IBUs through the brewing process and this really wasn't an experiment specifically designed to test the relationship between gravity and utilization. If you look at the gravity vs utilization graph on figure 4 (whirlpool results), there are a bunch of beers with gravities between ~12 and 15 Plato and only 2 beers at around 20 plato. Those two beers greatly influenced this regression line. Without them, when you just look at the scatter of beers between 12 and 15 plato - one would come to the conclusion that there is no relationship. The authors even acknowledged this:

"The scatter plots from Figure 4 show that hop rate and wort gravity both have a large impact on utilization, although the correlation of gravity and utilization was weaker at lower gravities. This is consistent with a previous study that showed no correlation with original gravities between 10.5 and 13.5°P (5)."

I do think because of these two beers influencing this regression line greatly - the "large impact" the authors state is grossly misleading. Why? If there is a statistical "large" impact or "strong relationship" the points would be a lot closer to the regression line (minimizing the standard error of the estimate) and the actual relationship, denoted as r (correlation) or Rsquared would be large. Unfortunately the r values were not even reported most likely because those statistics weren't even run. So to make a "large impact" statement simply by qualitatively viewing the scatterplot - is misleading and very subjective.

So this is obviously a retrospective and more of a qualitative type of research report based on beers ballast point had already brewed. I wish that they had beers included in this analysis between gravities of ~15.5 - 19 Plato - (which is specifically the range of gravities most NEIPAs live in). Looking at that gravity vs utilization graph on figure 4 - having data points along a full continuum of gravities would've definitely helped to substantiate or refute this relationship. Lastly - even if one were to accept the relationship as statistically significant - the relationship appears nonlinear - so simply saying as gravity goes up, utilization goes down wouldn't be telling the whole story. I would actually imagine that there may be a threshold of gravity where utilization may drop off like a cliff - but thats just my speculation.

So - while I applaud this author for reporting this - I will look for other sources of research which have specifically designed a study to look at this relationship. Until then - I think these data are no more informative in regards to this relationship than someones anecdotal experience.

Cheers - sorry for long post! :)
 

isomerization

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Looks like @VikeMan was on the right track. Isn’t a research article, but according to Palmer:

“Instead, the reason that higher wort gravity affects hop utilization is because higher wort gravity means more protein, therefore more hot and cold break, and higher yeast mass to be pitched, and these are the factors that carry isomerized alpha acid (and plain alpha before it can be isomerized) out of solution. In other words, wort gravity does not affect hop isomerization, but it does effect alpha acid and iso-alpha loss at various points in the brewing process."

http://beersmith.com/blog/2012/02/2...-beers-with-john-palmer-beersmith-podcast-33/
 
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Noob_Brewer

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Looks like @VikeMan was on the right track. Isn’t a research article, but according to Palmer:

“Instead, the reason that higher wort gravity affects hop utilization is because higher wort gravity means more protein, therefore more hot and cold break, and higher yeast mass to be pitched, and these are the factors that carry isomerized alpha acid (and plain alpha before it can be isomerized) out of solution. In other words, wort gravity does not affect hop isomerization, but it does effect alpha acid and iso-alpha loss at various points in the brewing process."

http://beersmith.com/blog/2012/02/2...-beers-with-john-palmer-beersmith-podcast-33/
This makes sense to me. So ANY grist high in proteins (extra grist OR one with lots of oats?) could do this. Not necessarily higher gravity. Soooo many variables!
 
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MBAA podcast 123 may also be of interest. Link to podcast is on this page: https://www.masterbrewerspodcast.com/guests/aaron-justus

Hop utilization (IBUs) is definitely affected by wort gravity, or (more precisely) there is a definite correlation between the two.

http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2018:

November 1, 2018 - IBUs vs Wort Gravity and Hop Stand Temps

Dr. Chris Hamilton of Hillsdale College in Michigan shares results of his experiments testing the effects of increased wort gravity and different hop stand temperatures on IBU measurements. He also updates us on his research with Clarity Ferm on gluten in beer.

If one follows people, not just forums, there's some additional information over in /r/homebrewing.
 

VikeMan

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This makes sense to me. So ANY grist high in proteins (extra grist OR one with lots of oats?) could do this. Not necessarily higher gravity. Soooo many variables!

But note that oats are not high in proteins, compared with barley.
 

2_gal_brewer

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They should try the experiment with just sugars and no proteins first over gravity range, then repeat for several known amounts of protein. Otherwise they have too many variables to figure what is happening. It does not seem complicated if you really want to find out if this suggestion about proteins is true.
I am not going to do it though :).
I se the chart in the linked source below and see that efficiency improves with reduced gravity. So for best effect then, I think why not just use pure water before adding sugars. I suppose boiling also has some effect on the grain extracted compounds, so maybe this is needed for the resulting beer too. But if brewing with extract, I do not see that this should be needed, as beer can be made with extract without boiling it.
So I would think that boiling hops in water then adding extract would be a good way to go. I have not tried it, as I use hopped extracts to make life simpler, then add more hops (aroma, flavor and incremental boiled bitterness) and grain steeps for custom results. For me that works fine.

Has anyone else tried just boiling hops in water then adding extract?

This might be helpful
 
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As a follow up to #11: Since my post in #8 (May 2020), the alchemyoverlord web site has added a couple of articles that may be relevant. Some recent discussion on those articles can be found here (link).
 
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