General Category > Kegging and Bottling

kegging and oxidaiton

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andyi:
Howdy,

New to kegging and Just kegged a pale ale two weeks ago and I getting oxidation off flavors.   I transferred from the fermenter to the keg (did not put down a blanket of CO2). Check for leaks, add 5 psi co2 to seal and burp to remove o2, disconnect let sit overnight in fridge, connect set to approx. 12 psi till carbonated. Where in the packaging process could the oxidation  happen?

Cheers

klickitat jim:
Yes. Could come from other things too.

HoosierBrew:
Oxidation can come from excessive splashing from primary into secondary (if you used one), or from splashing into your keg. And purging your keg with CO2 before filling is a good protective step to get in the habit of. Also, it's good to be sure your racking tubing is long enough to reach the bottom of the keg, to minimize the splashing. Did you use a secondary?

EDIT - Also, it looks like you purged the filled keg (which is good), but sealed with only 5 psi, disconnected and left it overnight before reconnecting? If so, that small amount of CO2 was likely not enough to actually seal the keg as some was probably absorbed by the beer, and may have allowed some outside air in past the seal to oxidize.
Constant pressure is best. I seat the lid with ~ 30 psi for a minute after purging and then reduce the pressure to my desired carbonation pressure (often 12 psi) and leave it there.

S. cerevisiae:
I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor).  Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes.    In essence, 2-nonenal is a hot-side, not a cold-side phenomenon.  Formation of this compound in finished beer occurs in the absence of oxygen.

troybinso:

--- Quote from: S. cerevisiae on July 08, 2014, 08:21:06 PM ---I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor).  Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes.    In essence, 2-nonenal is a hot-side, not a cold-side phenomenon.  Formation of this compound in finished beer occurs in the absence of oxygen.

--- End quote ---

Wow, I had no idea that there were hot-side factors to staling. It has been "accepted knowledge" that oxidation post-fermentation and at packaging is a cause of cardboard off-flavors described as staling. Is this not the case? What can we do to avoid staling on the hot side? And what are the staling effects that we can expect on the cold side?

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