The Role of Oxygen in Beer

After sanitizing the keg with star sand, I'm left with a ton of foam. Could that layer of foam protect from cold side oxidation until you purge the keg to carbonate or is there too much oxygen in the bubbles of the foam for it to be a viable theory? "I spent the better part of my kegging life up until about three years ago, not transferring beer into purged kegs and keeping the lid off," he says.