I always wondered when the dirty secret would get out. But I think it’s even worse: The author explains the ~100IBU solubility limit in WORT. But of course ~75% of bitter substances are lost in chilling, fermentation and ageing. So I was always under the impression that the IBU limit in BEER is around 75. If Pliny is really testing at 65, that sounds about right.
I’ve had that Malowicki paper for a decade. Its very illuminating. As I recall, the solubility limit for iso-alpha acids in wort is around 80 to 85 ppm (aka: 80 to 85 IBU).
The thing that has me intrigued is the existence of another bittering compound. I can’t recall its name, but its something like Humuline. Denny corrected me the last time, time for his input again. That compound is readily extracted during dry hopping and its not reflected in IBU measurement.
Vinnie used to say it was 95 IBU measured in the lab, a few have said it is 65 now. Last January I was in Pasadena, and Drew recommended a top at Lucky Baldwin’s, stoped and they had just tapped a keg a Pliny, it was not as bitter as I remember years back in Santa Rosa. I have talked to one guy from a large MI brewer that their DIPA was 113 IBU in the lab, and I would trust him as that was a tongue bruiser.
I presume those beers are using extracts? I recall Pliny was one of the first to do so. I was thinking ~75 is about tops for a beer made in the traditional way, relying on boiling hops for all the bitterness, which is probably what most of the small operations claiming insane IBU are doing.
Vinnie used to say 95 IBU and admitted to using extracts. The one I referenced didn’t, but it was a 10+ ABV beer, and I have read that the IBUs can go up with higher ABV. Often residual sugars hide the higher ABV.
I’ve been saying this for years, but once you hit about 60 IBU’s the other factors that affect bitterness play more of a role in differentiating two beers. The actual lab-measured IBU level means far less for extremely hoppy beers than something like a blonde ale or a malty lager.
FWIW, I’ve had an IPA lab-measured at 98 IBU. Its only hop addition was a large (~4oz/gallon) 90-minute flameout addition at flameout. To my palate, the bitterness was far less than a typical West Coast-style IPA despite the large measured IBU value.