Fest Lager...8 weeks later!

I posted earlier (https://www.seasonsofthebrew.com/post/to-err-is-human) about a fest beer that I was fermenting and thought I had messed up somehow. Check out the post above to hear the details.

Anyway, to check on the beer at that time, I had to open the fermentation vessel (I ferment in the same keg used for serving - will post on that separately). At this point the beer was 2 weeks into fermentation. I was thrilled that everything seemed great; while a bit "yeasty" it still tasted very good with no diacetyl or other off-flavors of any kind. I purged the keg, cold crashed, and left it alone to lager for a few weeks.

After 3 weeks of cold conditioning, I though I would give it a taste. Ugh...diacetyl butter bomb! I was so upset I thought about dumping it and giving up brewing altogether! After calming down (with the help of a couple of genuine Munich fest beers!), I recalled an article I had read on causes of diacetyl formation in beer and how to prevent and/or remove it (https://www.morebeer.com/articles/Diacetyl_formation). Given that it tasted great before exposing it to oxygen, this excerpt from the article was especially interesting to me:

Acetolactic acid is oxidized to diacetyl, and other constituents (for example, various aldehydes as well as wort-derived melanoidins and tannins) are reduced. In all of the mechanisms described so far in this article, this is done enzymatically by microbes, culture yeast, and, in adverse cases, by other guests in our worts. The reaction can occur nonenzymatically, however, in the presence of an appropriate oxidizing agent. Indeed, a widely observed but little discussed phenomenon occurs when diacetyl appears spontaneously in a beer that seemed to have normal flavors.

Ok, so here is where it gets interesting. As noted above, I serve in the same keg in which I ferment - i.e., I let the yeast settle to the bottom and use a floating dip tube to pull the clear beer from the top. This made me think that maybe if I brought the keg up to room temp and swirled it a bit to rouse the yeast, it might be possible for the yeast to wake up and reduce the diacetyl. After a full week at room temp, I threw it back in the fridge and let it sit for another 2 weeks.

I'm now a full 8 weeks since brewing this one and...lo and behold, the beer looks and tastes fantastic! No trace of diacetyl whatsoever and a nice, malty and smooth fest beer! So I guess giving the yeast a chance to clean up the diacetyl (even after cold crashing!) plus weeks of patience and time really worked!

So happy to have this one to enjoy during the last days of Oktoberfest. Prost!