I revived this question in a thread that was in the beginner's forum, but I thought it would be more useful to post it here and elaborate on it.
Certain physical and temporal restraints led me to primary and secondary by brown ale for one week each before bottling. I tasted the beer before bottling and it was very nutty, with no detectable hint of diacetyl. I opened a bottle yesterday just to sample (10 days after bottling) and it had a noticeable buttery diacetyl flavor. I imagine that this will go away with a little more time, but it brought a few questions to my mind.
Is it normal for beer with little to no diacetyl at bottling to have significant levels 10 days later? I usually taste samples as the beer is conditioning, and after several dozen batches, this is the first time I've had that happen.
Under the constraints present during bottle conditioning (no oxygen, limited sugar, increasing pressure), what is the capacity of bottle conditioning yeast to reduce diacetyl levels?
How do these changes occur over time? Would most of this happen in the first couple of weeks? After a month? 6 months? I was always under the impression that after a couple of weeks in the bottle, any flavor changes that occur are not a direct result of any active processes from the yeast, as they are dormant by then.
If the yeast do process diacetyl during bottle conditioning, what is the byproduct(s) that results from this? I seem to recall reading that the resulting compounds are flavorless.