How about beer?
Jason wins the prize!
Well, there isn't really a prize other than
the satisfaction of knowing that you were the first
to figure it out. Jolly good.
I ran across
it while looking for some other chemical information.
It was the Molecule of the Week on Chemstry.org.
"Beer flavor is a complex balance of sweetness
from sugars and bitter from the humulones in hops
(Humulus lupulus) flowers. When wort (unfermented
beer) is boiled, humulone molecules rearrange to
form the more soluble isohumulones (one example
shown here). Isohumulones retard bacterial growth
and contribute to beer's bitter flavor."
- Kirt Blattenberger