[Zach Grinnell]

Anyone done this before? Did it have a negative effect on the beer? Will the yeast consume the oxygen before it alters the flavor?

Thanks.

[HighVoltageMan!]

Probably not a big deal. Ideally it should be aerated at pitch, but some brewers will aerate high gravity at pitch and another aeration 12-24 hours later. I doubt it will hurt your beer much.

[dls5492]

IMVHO,I try to have enough healthy yeast so I don't have to worry about oxygenating.

[ravenwater]

I should think you don't need to worry here. Where there is cause for concern is introducing oxygen AFTER yeast have been pitched and become active, though as HighVoltageMan states some folks make an exception for high gravity beers where they oxygenate a 2nd time shortly into the fermentation which provides a benefit presumably (I've done it) rather than ill effect. For your question, if you oxygenate a bit prior to pitching that oxygen is dissolved in the wort, doing no harm, and waiting patiently to be used by the yeast when they arrive at which point they will process and eliminate it.

[jeffy]

I think it depends on whom you ask.  Some people may say that oxygen will stale the wort if added that long before pitching.  This may turn into a good experiment to see if it has an immediate or delayed effect or no effect at all.  Keep us posted on flavor and color changes.

[Kevin]

Probably no. Especially if the vessel was sealed. Look up No Chill homebrewing.

[majorvices]

You'll be absolutely fine.

[ynotbrusum]

I suspect that you will be ok, but I don’t want oxygen added until I have yeast present to take it all up.  Look into low oxygen brewing to get more information.  There are different camps on this issue....

[Bilsch]

The flavor components that make beer taste fresh are antioxidants. Any oxygen that gets into the beer, that is not scavenged by the yeast, will stale the beer. This is why brewers strive to protect the beer from oxygen. The fact is you did do damage, how much is open for debate.

[majorvices]

the question was "are you in trouble"? and the answer is - no. While oxygenating 12 hours before pitching yeast may not be the best practice it isn't going to ruin your beer. Will you win silver as opposed to gold if you did everything else right? Possibly. In other words, not something to overly stress over.

[joe_meadmaker]

Not directly related to your question, but I'm curious what style of beer you're making.  Oxygen exposure will affect certain styles and flavors more so than others.

I think it depends on whom you ask.  Some people may say that oxygen will stale the wort if added that long before pitching.  This may turn into a good experiment to see if it has an immediate or delayed effect or no effect at all.  Keep us posted on flavor and color changes.

And +1 to this.

[Saccharomyces]

The flavor components that make beer taste fresh are antioxidants. Any oxygen that gets into the beer, that is not scavenged by the yeast, will stale the beer. This is why brewers strive to protect the beer from oxygen. The fact is you did do damage, how much is open for debate.

Part of what brewers perceive as staling in finished beer is that it lacks a viable carbon source other than ethanol.  When finished beer that still contains viable yeast cells is exposed to O₂, the cells consume the O₂ and under go a diauxic shift where they start to consume ethanol as their carbon source aerobically, reducing ethanol back into its precursors.  That does not produce the flavors we associate with truly oxidized beer, which is the result of filtered beer being exposed to O₂ during packaging.   The reason why brewers still bottle-condition beer is that the addition of priming sugar gives the yeast cells something other than ethanol to consume after they take up the O₂.  The modern process involves filtering and then adding back a small amount of yeast with the priming sugar.

Wort is not finished beer.  It is rich with sources of carbon.  The main threat that arises from waiting to pitch a yeast culture in wort that has been aerated comes not from staling, but from microbiological competitors, especially aerobic microbiological competitors, mainly wild yeast.  Remember, a brewery is sanitized, not sterilized.  There is always a small amount of house microflora in every fermentation.  That is big part of why breweries tend to have a house flavor.

[Bilsch]

Part of what brewers perceive as staling in finished beer is that it lacks a viable carbon source other than ethanol.  When finished beer that still contains viable yeast cells is exposed to O<sub>2
[/quote/]

I believe you are referring to stage B and C staling and I am talking about A. You will oxidize polyphenols very quickly.</sub>

[goose]

To build on Mark's comment concerning microflora in the wort in every brewery I always remember the statement I learned long ago,
"Fermentation is a race between the yeast and bacteria.  You always want the yeast to win."  Although you are probably be OK, pitching right after aeration is always the best practice to make sure that the bacteria doesn't gain a foothold in your fermenter.

[RC]

I wouldn't worry about staling. The main reason oxygenating the wort should be done right at pitching is so that the dissolved O2 doesn't off-gas into the headspace before pitching. Contrary to popular belief, oxygen is not very soluble in water (or wort). The 12-hour delay means that the yeast probably didn't get the full benefit of that added oxygen because much of it off-gassed into the headspace. Whether or not you are "in trouble" because of this depends on how healthy the yeast were to begin with and how concentrated the wort was.