Just wondering if anyone knows the answer to this. I keg my beers and there is a definite change in hop character that occurs throughout the beers life, but does the actual IBU change from say first tapping the keg until the last pint?
Yes, the IBUs decrease wth time. Do a web search for the Delgleish curves on beer aging.
Or read this, found a graph.
I would have thought they might decrease, but after googling as suggested actually came up with this post from 2011
which discusses this research paper
For discussion here is the post linked above. Seems a bit aggressive on the decrease, but also notes the numbers are not precise. I’d credit the author of the post if I knew who mdma from Norway was.
Of course, other variables do come into play, so these figures can’t be taken as exact, But then, as we all know, that’s how it is with brewing. Our malt isn’t exactly the color on the label (usually a range of values), and hops aren’t the bitterness on the pack since they degrade from the get go. So, although not exact, these figures should offer a good estimate.
[/quote]
I have seen those references. There was also one somewhere that pointed out the ratio is less for short boils times, more trans than Cis, so late hop beers will have less bitterness stability.
Thanks for the info and links. Didn’t realize it would be that much decrease. As for “late hop beers will have less bitterness stability”, that sure makes conceptual sense to me because I feel that the hop flavor (which I know isn’t bitterness but is a function of hopping), from dry hopping seems to be the first to dissipate in my mind.
YEP
I tend to brew beers that get better with age. Stouts, Scotch, Quads.
I bitter them up figuring I’ll loose some.
As for American Pale Ales, the rule of thumb is drink em when you got em.
Nice chart mdixon. Thanks
Have Fun