I typically use high quality flour from a mill directly for baking which have no additives. However I would prefer to refresh my starter with a cheaper organic flour from the supermarket, which is almost half the price but has Absorbic Acid added. Would the absorbic acid additive affect the starter in any way?
ascorbic acid as an additive is simply a vitamin c additive. i wouldn't think this would interfere with your starter since the quantity added is usually very small and acts as a natural flour preservative.
check out this link on tfl.
http://www.thefreshloaf.com/node/7416/ascorbic-acid
hope this helps, claudia