Shelf Life For Hoppy Beers?

[Shepherd5]

My last double IPA was dry hopped for ten days, tasted fantastic for about two weeks in the keg. By the end of the third week, it was very bitter, sour, and acidic tasting. I must tell you that this batch was really incredible! I have never tasted anything so good. By the end of the third week, it tasted borderline crappy.

So my question is this: Is this typical for the hoppiness to diminish so quickly in the keg with beers that use alot of hops?

I considered the possibility that it was infected, but it was still drinkable at this point, just not nearly as good. I also considered the possibility that it had been overcarbed, but adjusting that down did not make any difference.

Your thoughts?

 

[33rdstreet]

Aha! You have over carbonated it! I've done exactly the same thing. With hoppy beers, I find the taste profile is better at lower pressures (20-25 psi). Anything above 25 might acidify the beer too much (lower it's pH).

This is what happens: the bittering chemicals in hops are grouped into two categories called alpha and beta acids. Alpha acids provide most of the hops flavor; cascade, centennial etc. all have a lot of alpha acid and little beta acid. However, as you condition beers for awhile, the alpha acids deteriorate and beta acids (albiet a very small amount typically) tend to take over by means of oxidation. This reaction imparts a very unpleasant astringent taste. Oxidation, in this form, is common at a lower pH (tieing back to the carbonation issue). So, careful carbonation is very important for beers with IBUs above 40.

I don't know if there is a fix for this. You could try uncarbonating and recarbonating the beer. I have not tried this, however.

Hope this helps!