Glass is a perfect O2 barrier, but most vacuum pumps do not create a perfect vacuum. I suspect that a FoodSaver is not even close to perfect.
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agreed, but is it any better or worse than a bag?
jeff - the lids are on tighter than when I have used the in actual canning. i don't think you will get O2 in via the lid, that is for sure.
One would think that O2 does not get into a beer bottle, but it does. The partial pressure of O2 is the driving potential. The cap material has permeability, so it gets in, as the bottle can have very low O2 levels, and the atmosphere has 21% O2. This is why Sierra Nevada went to the pry off caps, a new low permeability liner required high clamping loads than a twist off could provide.