Originally Posted by bondolon
Corn sugar is fairly neutral, and adds next to nothing to the beer, save carbonation. LME and DME can change the flavor of the beer slightly if the type of extract differs from the sugars in the recipe. Saving off some wort to add the sugars back in can prove to be a pretty good idea, if you're going for having only the appropriate sugars in the beer, but it does take some calculation.
Thread back from the dead!
I doubt very much that malt extract is going to change the flavor of
the beer unless it's dark malt extract and you used pilsner malt or extract
as the base.
DME which is mostly maltose is not fermentable by zymomanas and corn sugar
is, so its extra insurance against infection.