Canned beer has become fashionable amongst some of my fellow beer nerds, and lack of oxygen uptake in the container causing staling has been one of the attractions. This prompted Rob Lovatt from Thornbridge brewery to point out to that oxygen pick up after packaging is only part of the story and small scale canning lines have a real potential to introduce oxygen during filling.
This did still leave me wondering how much oxygen can get into bottled beer. So I asked the engineer who sits next to me and he said very little unless the capping goes wrong. But it would still be nice to have a figure. And then, as if by magic, an article by Peter Heumüller and Graham Jennings in Brewing and Beverage Industry International had exactly that:
"Oxygen permeation rates are detectable, although the metal of the crown cork and the glass bottle are perfect barriers. A detailed measurement showed values of typically 0.001cm3 / cap / day."
So there you have it.