I brewed my first real lager about 5 weeks ago using SafLager W-34/70 German Lager Dry Yeast. I had consistent temp control of 13 degrees. When it had reached ~ 1.018 I raised the temperature to 15 degrees and let it finish fermenting another week to 1.007. It was almost 4 weeks in the fermenter before I put it in the keg. It is now carbonated and I am planning on letting it condition in the keg, but I had to give it a taste. It has a mild green apple taste and maybe a little in the smell. I assume this is acetaldehyde. I had the same thing happen with my very first beer and in less than a week it was gone, but I can’t remember if I had stored it cold or warm. Should I leave the keg in the fridge or should I put it somewhere warmer? How long should I expect it to take before the green apple taste is gone?
I would recommend leaving it in the fridge. Reduction of acetaldehyde typically happens during the lagering phase so just give the yeast some more time to do this and unless the levels are extremely high this should go away.
I left it another month in the fridge and the green apple taste is gone.