« on: February 10, 2011, 07:44:49 AM »
Trying to pinpoint the cause of my recent bout of acetaldehyde in my Czech Pils. In six years and thousands of gallons of beer, I've never experienced this flaw before, so it really has me awestruck, especially since I make a pils or dortmunder about every 4-5 batches.
Granted, this beer is just shy of 6 weeks since brewdate and the green apple appears to be working its way out based on samplings...but I'm wondering if cold crashing my pils prior to kegging is the culprit???
I primaried for 3 weeks+ 5 days before kegging, but the last during the last 4 days, I brought the temp down from drest at 60-62 down to 40, dropping 5df each morning before work. But crashing before kegging is not a regular practice for me - I usually don't get around to it and just keg at drest temp and then throw the kegs in the lager fridge.
Anyhow, I ferment in a 14.5 gal conical, and when I crash, I put sanitized foil with rubberband around the stopper so as not to suck back in the liquid in the airlock, but I got to thinking - did doing this with the pils cause the beer to suck in so much air that it caused oxidation which led to acetaldehyde, or am I fretting over 'green' beer that will lager away fine over the next month?