Back in March of 2007, my wife Jennifer and I brewed a batch of beer at the house of some friends of ours. (See my blog entry at the time for more.) The beer was a Flander's red -- a sour beer -- and it had been sitting in a bucket for over a year now. A few months ago, I poked my head in the room where the bucket was sitting and saw that the airlock was completely dry. I filled it, but had no idea how long the beer was exposed to air. Last weekend, I finally got around to racking it to a keg and . . . it tasted awesome! It had a very "clean" sour aroma (as opposed to a sour aroma with lots of acetic, "barnyard" or other off characters) and was tart, but not over-the-top puckering sour.

How could this be? Any normal beer would be awful after sitting that long, in a bucket, on the yeast and trub from primary and exposed to air (both from the diffusion of oxygen through the plastic and from letting the airlock dry out).

First off, sour beers actually do better with a little exposure to oxygen while they condition. Buckets "breathe" more than actual barrels do but, obviously, not so much that a sour beer will be ruined. Also, the yeast and trub from primary fermentation can help slowly feed the souring microorganisms as the beer conditions. In a "regular" beer, the gunk at the bottom of the fermenter eventually starts tainting the beer with "nutty" and other off flavors.

Still, given that the airlock dried out, I was expecting the beer to be overly acetic. Exposure to air allows aerobic microorganisms, such asAcetobacter, to grow on the surface of the beer, giving it a vinegar-like flavor and aroma. (I honestly expected the keg to be a temporary holding vessel until I poured the beer down the drain.) The only thing I can think of is that the thick pellicle protected the beer from oxygen. That and the amount of time the airlock was dried out must have been short.

So basically, I was very lucky and turned some shameful neglect into a great sour beer.

I also racked over a Vienna lager that had been sitting in my conical "forever." Long story short; not all beers benefit from long periods of inattention. It's drinkable, but not good by any stretch of the imagination.