Ascorbic Acid

I noticed my LHBS sells ascorbic acid (vitamin C), supposedly to add acidity to wine, and it reminded me of an episode of Good Eats I saw a few years ago where Alton Brown used crushed up Vitamin C tablets (a strong anti-oxidant) to prevent oxidation in some sort of food going into the freezer.

With all the obsession in homebrewing and the lengths we go to in order to prevent oxidation in our beer, why does ascorbic acid seem to elude our homebrewing toolbelts? It seems that you could get pretty good protection against oxidation while keeping it below the taste threshold.

I don't consider myself to be stupid, but I KNOW this must have been thought of countless times before... so is there a good reason that the use of it hasn't really caught on? Is there a reason that I really SHOULDN'T do it? And I guess a bit tougher question is...if it can be used, must I use ascorbic acid base, or can I use a salt (eg. calcium ascorbate)?

Even if it's not ideal during fermentation (no idea if that's actually true... I doubt it though), I think it'd be great for those of us who bottle carb, not just for the oxidation encountered during racking, but largely in lieu of purging the bottle with CO2, since the lack of an airlock obviously means the CO2 is no longer forcing oxygen out of the heardspace.

If lower ph is what you're after, calcium ascorbate is buffered at about 7.0 so it won't work. Also, ascorbic acid can become an oxidant once reacted at low concentrations. I don't know at what concentration its would remain an antioxidant.

You occasionally catch blurbs about adding various antioxidants to the process--citric acid, ascorbic acid--Papa Charlie is supposedly an advocate of small amounts of cinnamon. It's all pretty vague, though.

The question is: Is oxidation really a problem in your beer in the first place?

If not, then why add something to address a problem that doesn't exist?