How to Categorize the Bitterness in Hops

Me too. The difference of course is that the FWH study conclusions were simply misinterpreted by American readers. The cohumulone study may have just been flawed.

 

The issue of cohumulone and the quality of bitterness is also addressed in the paper on p. 41 of this pdf file:

http://www.lfl.bayern.de/mam/cms07/ipz/dateien/issn_1814-2206__proceedings__kiew-2013.pdf

The paper contains a review of research on the topic.

Cheers!

 

Great stuff. Not what I would have guessed I'd be reading at 5AM, but great stuff. I think it is really interesting that cohumulone isomerizes more readily than the other alpha acids, so that high cohumulone hops should give higher ibus, all other things being equal. I don't suppose anyone is going to start tweaking the IBU calculators until the cohumulone percentage is published on hop packaging right along side of the alpha acids. Of course, the calculation still would only work as a coarse estimate due to all the other idiosyncracies of conversion related to process details. Too bad I didn't come across beer chemistry articles when I was an undergrad in the 1980s. I might have ended up studying something cool like the chemistry of beer (instead of the chemistry of other cool things).

 

“I don't suppose anyone is going to start tweaking the IBU calculators until the cohumulone percentage is published on hop packaging right along side of the alpha acids.”

During the Q&A session of the presentation by Mike Karnowski he mentioned that if you are using low cohumulone hops you need to utilize a ‘correction factor’ in terms of the amount of hops used. He made mention of using 50% more than what would be indicated by the hop utilization estimator.

Cheers!

 

It should be possible. Even without a cohumulone % on the package, a typical cohumulone proportion for the variety would be use useful. But I guess the question is would it potentially do more harm than good? We all know what a "12 IBU" hefeweizen tastes like and how to make it. I wouldn't want to adjust that and say "that's only 8 IBUs" and then increase the noble hops to get up to 12 true IBUs.

I think if a tweak is in order, we can do a lot better than a rule of thumb.

 

Certainly seems like you would want to put some bounds on high and low cohumulone, even for a rule if thumb. A formula for incorporating % cohumulone into ibus would be better, but typically we don't know it, and while we can find these percentages for different hops, how they vary with crop year, location, etc. may be poorly known.

 

I looked into incorporating cohumulone % into IBU calculations a while back, when I was thinking of writing up an article on the subject of utilization in the boil and in hop stands. I do not recall any specifics at this point, but my feeling (at this point in time) from that research is that the variation in utilization is not as great as 50% among hop varieties when cohumulone levels are accounted for.

That said, I do think that one could profitably account for differences in average cohumulone levels that, on average, would give more consistent (if not better) IBU estimations. This might be useful when one wants to substitute hops in a given recipe.