Bitterness in beer is important, as is the way that bitterness is perceived. Certain types of hops are said to impart a more harsh bitterness, while others apparently produce a smoother bitterness, which many believe to be a function of different levels of cohumulone. Interested in the impact hops with different levels of this compound have, we performed an xBmt to test it out. Results are in!
Have you read this?
http://www.barthhaasgroup.com/johbarth/images/pdfs/2009_BWI_Cohumulon.pdf
There was also a talk at NHC a couple years back where the IBUs were equal, I didn’t attend that one. You might have to listen to the audio fill.
Great article! If I didn’t link to it in my xBmt article, I meant to, it’s one of the many I referred to while writing.
After doing a dive into this subject, I concluded I would worry about it as much as I worry about HSA.
Fantastic xBmt. I think it’s good to know that not every single piece of conventional wisdom out there is false – we actually heard one thing right for a change. Cohumulone does make a difference. I’ll bet I personally would prefer the smoother low CoH type, but I can just see homebrewers everywhere now who will start bittering everything with Chinook to take their IIIIIIPAs to the next level. So, congrats(?). ;D
I have long preferred Chinook for bittering APA/AIPA. When people tell me they use Magnum for those, I kinda wonder why.
I definitely like Chinook to bitter AIPA. It has a nice IPA bitterness.
This doesn’t surprise me, either. I have long preferred to go in the middle by adding a small amount of Chinook (on the order of .25-.5 oz in 5 gallons) along side a larger dose of low cohumulone hops to give a bit of an edge to the bitterness without getting harsh. To me, that’s the best of both worlds.
Thanks for another great xBmt, Marshall! When I do batches of single-hop trials, I definitely notice a difference in the quality of bitterness between the different hops. It would be interesting to go back to some of my tasting notes and see if the CoH levels line up with my experience.
I wonder if this has any bearing on why beers with no bittering addition (i.e., all IBU’s from the whirlpool) seem to have a smoother bitterness than those with a traditional 60-minute addition. It could be just hop choice coming into play, but maybe less iso-CoH is produced by that technique. Every time I see one of these experiments it makes me wish I had a GC/MS in my garage to help answer the myriad of other questions it seems to lead to.
Given the narrow margin of significance on this one, I’d say this would be a good candidate for an IGOR followup, to see if a bigger sample size will result in a clearer conclusion.
It’s a purely subjective, eye of the beholder thing. So that’s never gonna be resolved across an entire hobby or industry, that’s for sure.
I was just posting on another forum that I use Hallertau for much of my bittering. Two reasons: 1) I grow my own so I always have some, and 2) because I think Hallertau tastes awesome when used for bittering. I pick up a lot of flavor from it, and the LONGER it’s boiled, not the shorter. Right wrong indifferent, that’s been my experience. And, hey, I’ve got several ounces of homegrowns sitting here and it’s been like a constant 4.8-5.0% alpha for the past 6 years (or at least it tastes that way to me), so why not. I’ve never been impressed when reserving them as late additions, but they’re great for all my bittering.
I also am a huge fan of Chinook. One of the first IPAs I ever made was an all Chinook Rye IPA, so that’s probably why I like it so much.
I so hope D&D have their IGORs redo this one! I definitely plan to continue playing with it. I only wish there was a better way to get differing CoH levels without using different hops. Hmm.
Yeah… guess you’ve got to seek out that tincture of pure CoH. Good luck with that!! I hear you can get THC though.
When you said D&D, my mind drifted for a second… almost makes sense, too. 
Maybe all 3 of us should put our heads together and see if there’s a better way to do this.
I sense an inevitable establishment of either a merger or a mutual respect society of some sort.
Another part of me wishes James Spencer and/or Chris Colby would also jump on board somewheres. It would be like a non-holy non-trinity at that point… mega nerdy pragmatic awesomeness… jolly good and which no one could deny.
I wish I could find it, but someone a couple weeks ago emailed me a link to purchase actual CoH… or something like that. I feel like that’s really the best way to get where we want to go. Heads together, indeed!
We’ve already got the mutual respect society. That’s why we ask Marshall to come on the podcasts to comment on our experiments.
I’ll drink to that. 
My thought is that repeat testing should use a variety of hops that have high and low cohumulone levels, this way a trend would tend to point towards cohumulone as the likely difference. If you use the same two hops repeatedly, then the results could be from some other difference between the two.
I think you’d want enough bitterness to be able to detect a difference if there is one, but otherwise as small of a hop addition as possible to minimize other flavor contributions. In other words, high alpha but low oil content would be the ideal hop selection for this.
The Rigby paper referenced in the Brulosophy article says cohumulone is isomerized at a faster rate than humulone, so the difference might simply be that high cohumulone hops end up giving a higher final IBU level, even if AA levels start the same.