A few weeks ago, I pulled some of an IPA I was making and force carbonated it so my friend and I could try some. While it was not the bitterest I have tasted, it was definitely an IPA. I bottled the next day. I tried a bottle last night after it's been in for about two weeks. I couldn't taste any hops at all. It was still a delicious beer, but it tasted a lot more like an amber than an IPA. What process could happen inside the bottle that could cause practically all the hop flavor in a beer to dissipate, and how could this be prevented in the future?
Hm. Hop flavor will degrade over time but usually it takes a few months or more, not a couple of weeks. Hop bitterness will degrade as well, but it takes much longer, with about 75% of bitterness intact after a year. That being said, I'm guessing there are other factors at play here, not just degradation.
What temperature did you try these beers at? Temp can greatly influence taste, and if the beer you pulled off was warm while the bottled beer was cold, it could seem like the bottled beer had less flavor. This is the only thing I can think of offhand, it might also be good to post you recipe so we can troubleshoot it better.
I've found that with hoppy beers, that "flavor" is really an aroma most of the time. The only way I've had any luck getting any sort of hoppy aroma is by dry hopping. Add an ounce for the last week before bottling and you'll be surprised how much the flavor profile changes.
Here is a potential answer to your question:
My question is what temperature did you store the bottles? Isomerization of the alphas (the source of the hop bittering) is definitely the most likely culprit in this case. Hoppy beers in general need to be kept cold (well under 70F) to maintain the bite.
-1 since isomerization of alpha acids is exactly what gives beer a hoppy flavor. Isomerization occurs in the boil and only isomerized alpha acids are really present in the final wort, unisomerized alpha acids are not water-soluble and don't have much taste. Did you maybe mean oxidation?– pjreddieSep 18, 2011 at 21:41
did you check the link? Was just trying to point BC to what would be a helpful link. BTW- all alpha acids can dissolve in a water-based solutions (simple solubility rules indicate that this is possible, all corboxylic acids being polar to some extent and alpha acids are relatively low MW) whether isomerized or not. The real question is the nature of the isomerization and at what temperature, as higher temps yield different isomers than lower temps. Basic organic chemistry. Is it not true that hoppy beers should be stored at lower temperatures? The literature indicates that this is the case.– drjSep 19, 2011 at 1:32
Oxidation would not occur in an anaerobic environment such as a bottle. Unless you are talking about reduction/oxidation and that may indeed occur, but the result would be different isomers of the alpha acids forming, including the breakdown of some that formed during the high temperature stage of the brewing. And a subsequent loss of desirable flavonoids.– drjSep 19, 2011 at 1:44