We are testing a sample of a bake-stable ascorbic acid. How do we successfully measure vitamin C after baking to know whether this product worked?
Measurement of the total reducing equivalents of a liquid extract of the baked sample both before and after addition of ascorbic acid oxidase (to oxidize and remove the ascorbic acid; available from Genzyme) should be a usable procedure to determine the free ascorbic acid in baked bread. I presume that any assay procedure for ascorbate when combined with AAO (to remove background interference), maybe even the dipsticks from Sigma, when combined with appropriate standards should work and avoid the more complex spectrophotometric procedures and calculations outlined.