Machinelf: I'm standing in my office, giving you a slow clap right now.
Genius!
Here I stand in my office, bowing with gratitude.
Regarding the point of the thread, I've always heard that the essential oils that are responsible for aroma/flavor are volatile, so I would assume that they simply break down over time.
Once hops are used in the brewing process, a whole different set of complex variables come into play. The bittering and aromatic characteristics of hops come from resins in the hop flower, which are made up of alpha and beta acids. Different hop varieties have different levels of each acid, making some more desirable for bittering as the alpha acids are isomerized in the brew kettle, and others better for lending a floral nose thanks to the beta acids left behind after boiling.
“From addition times in the kettle, dry hopping, loss of oils from different fermentation temperatures, and fermenter design, the list of variables impacting aroma and bitterness goes on and on,” said Grossman. “But in a nutshell fresh hops are better in our opinion, if you are looking for lots of clean robust aroma.”
Tom Nielsen, Sierra Nevada’s senior research analyst focused on hop degradation, says that their research has shown that after about two and a half to three months, hop aroma in a packaged beer, derived mainly from beta acids in the hop flower, has already started to diminish significantly.
...
Gerri Kustelski, director of quality assurance at Summit Brewing in St. Paul, agrees.
“Organoleptically, there may well be discernable changes,” Kustelski said. “Bitterness can be masked by oxidation and aging, and aroma even more so. You begin to slowly lose the aroma imparted by dry hopping fairly quickly, possibly within several weeks. Packaging and distribution processes including shipping and temperature control can affect the flavor stability of beer and, thus, affect the perception of hop aromas and bitterness.”
"The major mechanism for the loss of hop aroma compounds from beer appears to be chemical degradation . The most likely pathways for degradation of terpenoid and sesquiterpenoid compounds are reaction with oxygen in the headspace of the bottle and acid hydrolysis."
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On deck: Little Bo Pils, Bretta Off Dead (Brett pale)
Secondary: Oude Bruin, Red Sky at Morning (Sour brown ale)
On tap: Saison Duphunk (sour), Amarillo Slim (IPA), Earl White (ginger/bergamot wit)
Bottled: Number 8 (Belgian Strong Dark Ale), Eternale (Barleywine), Ancho Villa (Ancho/pasilla/chocolate/cinnamon RIS), Oak smoked porter (1/2 maple bourbon oaked, 1/2 apple brandy oaked)
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