My brewing society has been talking about Diacetyl for some time now. This is what we have posted that is straight out of "How To Brew"
Diacetyl is not actually produced by the yeast. The vicinal diketones diacetyl and pentanedione are created chemically by oxidative decarboxylation, (i.e...
As far as I know, the two main ways to get Diacetyl is if your wort cooled too slowly, say overnight, and the other way is if the beer was racked into secondary carboy too soon which means the yeast did not have enough time to absorb the Diacetyl. It looks as though you allowed enough time in...