Does beer foam contain a significant amount of oxygen?

[Toastkid]

I often fill plastic mixer bottles with my homebrew, to take camping etc. It comes from a pressurised keg and I always make sure the foam comes right to the very top before I put the lid on. My thinking was that the foam must be made solely of beer and CO2, and won't have any oxygen (well not more than a trace anyway), so when it clears, i'm left with only beer and CO2 in the bottle, and it won't go bad due to oxygen spoilage. But, is that actually the case?

 

[peebee]

It's fine.

If you splashed the beer in, then perhaps you'll drag some air in. But then the beer would foam so much, you'll spend all day filling the bottle. If you are worried, stick a bit of flexible tubing on the tap to fill the bottle from the base ... in fact, do that anyway (you probably do?) or you'll still spend all day filling bottles.

 

[Toastkid]

ah, tubing! Of which I have lots. Good call, I do always spend a lot of time filling bottles because of all the foam. If i'm in a hurry I suck out the foam then keep going :) But yes, I will definitely do that. I can probably use the standard 10 mil pushfit connecters on the taps, they're the plastic picnic tap variety. Nice one, cheers.

 

[Hazelwood Brewery]

You could also use 2-litre fizzy drinks bottles, add a little priming sugar (dissolved in boiled water), and squeeze the bottle to push out that last bit of foam. The secondary fermentation from the priming sugar will fill the head space and re-pressurise the bottles. You can have lots of nice beer for weeks if you fill enough bottles!

Alternatively, take an empty pressure barrel and some CO2 bulbs and get a local brewery to fill it for you. I do this.