I haven't gone through all the replies on this thread, but I was wondering if anyone else has experienced noticeable diacetyl in this brew.
I used this recipe as a base, and added the zest of 8 blood oranges to the boil at 10 minutes, and the flesh of the oranges (after steeping in 190 degree water for 10 min) into the primary. On a side-note, unfortunately, all that work zesting oranges didn't really pay off. It has a slight orange aroma, but no orange flavor whatsoever.
I also used WLP029, instead of wyeast, fermented at 62 degrees for 12 days, and cold crashed for about a week then kegged.
My wife was the first to point out that the beer tasted like popcorn, and while I didn't notice it at first, when my palate is clean (first sip or after food), I can detect it too. Based on what I can find Kolsch yeasts aren't supposed to be big diacetyl producers, but now I'm wondering if I should have kicked this one up to 68 for a couple days, prior to the cold crash.