Exposure to Oxygen, Potential for

Hello, while I was at work today, my son took out the bung to my Irish Red for a few minutes. My wife put it back as soon as she noticed which made me realize I really dont know much about the potential issues exposure to oxygen can cause (and how long is too long?).

I know contamination could happen from bacteria in the air and whatnot but what are the other bad things that could happen and is a couple of minute exposure long enough to cause a potential problem?


Stale or cardboard flavors is usually from oxygen post fermentation. Usually we are talking about splashing of the beer when transferring to a second vessel or bottling bucket/keg.

http://www.howtobrew.com/section4/chapter21-2.html http://www.howtobrew.com/section1/chapter6-9-3.html

Casual exposure from the air lock being off, you more apt to pick up an airborne containment IME.

If the beer is still actively fermenting, CO2 will drive the O2 out.

Thank you for the info and quick reply, appreciate it! Will have to wait 3 more weeks before I taste it… seems like 3 years!

C02 does not seem to float off readily, witness when you open a bottle and the mist stays there. Probably the same in your carboy.

I was at the Jack Daniels distillery, and walked a catwalk between open topped fermenting tanks of corn mash. Each is covered by a foggy layer of CO2. It actually dampens the smell. The tour guide allowed us to draw our hands up through the mist to our faces - and experience an explosion of mash laden co2 rocking our sinuses like horseradish! I’ll smell that forever!