Priming, Bottling

[Bobsers]

I know that we aerate the wort to ferment. I've read that when priming and bottling, we should avoid the introduction of air as much as possible into the bottling bucket. Where does the oxygen come from that the yeast requires to carbonate the bottles? I would expect that when fermenting with an air lock that there would be little, if any entrained oxygen left in the beer at the end of fermentation. What am I missing? I'm about to bottle my first 12 gallon batch.

 

[foolsbrew]

Oxygen gets in whenever you are pouring your beer into anything, or the bottle, and when you are capping the bottle there is some oxygen there too. These amounts aren't enough to cause too many off flavors though. In commercial settings, this is usually entirely avoided. They scrub the oxygen, pour the beer, and force carb. Neat machinery.

More importantly though, oxygen isn't needed for fermentation/carbonation. Yeast uses oxygen to (mostly)multiply. That goes on until they run out of oxygen. The remaining sugar gets turned into alcohol and co2. Bottle carbonation is just more of the latter process.

 

[Coohang]

You are correct in the idea of not introducing any additional oxygen post fermentation. The best way I have heard it explained is to “avoid splashing” when racking to your bottling bucket or stirring in priming sugar. Place the capped bottles in a warm location (at fermentation temps or just above) and let them do their thing.