I disagree with the others posting that the yeast will clean up diacetyl once active fermentation has stopped. They may clean up some, but they won't be able to clean it all if the yeast have thrown a lot of diacetyl.
Try krausening, this usually clears the beer of diacetyl and is very traditional in German breweries using traditional lageirng techniques. Take a small amount of krausen from an actively fermenting beer (preferably a lager or a clean fermenting ale yeast) and pitch it in your beer. Alternatively make a small starter and pitch active in your beer (dry lager yeast would work fine for this).The active yeast should clean up the diacetyl.
To me, I have experienced diacetyl in 2 ways.
Case 1: When I sample the beer very early after fermentation has ended and there is a slight butter taste and slickness. This often occurs (in my experience) with yeasts that flocculate fast. In this case, patience is often enough to clean up the diacetyl.
Case 2: The beer has a ton of diacetyl from some brewing error on my part. In this case, adding a krausen beer at 10% of the total volume of the beer which needs rescuing has worked for me to clean up the diacetyl.
It's hard to know which case you have without lots of experience. But if you wait a week and still have artificial butter flavors, then don't package, take the time to krausen. Diacetyl gets worse in the keg/bottle.
PS. I can't stand the butter flavor in beer. At Universal Studios (theme park) in Florida they sell Butter Beer in the Harry Potter parts of the park. The idea disgusts me. I passed. I did get a Duff beer in the Simpson's part of park though. Not so good, but, fun.
Topic: Diacetyl rest left too late? (Read 9294 times)
