While browsing this interesting document online Table 1 immediately piqued my attention. According to the table O2 contamination from bottled CO2 is only dependent on O2 residual levels in the CO2 and how many volumes of CO2 you need to push into the beer to achieve desired carbonation.
As this seems to openly contradict Dalton's law I looked for an explanation in the accompaning text and found what to me seems to be a very convincing one. The author based the table on the assumption that we are force carbonating using a carbonation stone and that we are doing it right, that is to say the bubbles all get fully absorbed into the beer without ever rising to the surface. Since CO2's solubility is much higher then O2's the partial pressure and thus the solubility of O2 will steadily rise untill all contaminating gas is dissolved as well. On the other hand, if we apply a steady pressure on the headspace and wait for CO2 to slowly dissolve at the headspace/beer interface then the partial pressure of residual O2 combined with its lower solubility (one order of magnitude less than that of CO2) will cause a negligible amount of O2 to go into solution, provided the bottled CO2 doesn't have an abismally low purity grade.
As I never felt the need to rush carbonation I've always been using the slower method. As it turns out I was doing my beer a favor as far as oxidation is concerned.
As this seems to openly contradict Dalton's law I looked for an explanation in the accompaning text and found what to me seems to be a very convincing one. The author based the table on the assumption that we are force carbonating using a carbonation stone and that we are doing it right, that is to say the bubbles all get fully absorbed into the beer without ever rising to the surface. Since CO2's solubility is much higher then O2's the partial pressure and thus the solubility of O2 will steadily rise untill all contaminating gas is dissolved as well. On the other hand, if we apply a steady pressure on the headspace and wait for CO2 to slowly dissolve at the headspace/beer interface then the partial pressure of residual O2 combined with its lower solubility (one order of magnitude less than that of CO2) will cause a negligible amount of O2 to go into solution, provided the bottled CO2 doesn't have an abismally low purity grade.
As I never felt the need to rush carbonation I've always been using the slower method. As it turns out I was doing my beer a favor as far as oxidation is concerned.
