Hi,
Well after doing some research I can see that the reference I used may have been out of date. I found several references to more recent research at the University of Texas.
Ascorbic acid is a good antioxident, but needs low Ph and sulfur dioxide to work well and can in some cases result in off tastes when used in beer.
I will update the description and post it as a data update in the next few days.
I will leave it on the MISC list - as you can still use it for wine recipes as well as as a preservative for home-made soda.
Thanks for catching this!
Brad