I found this by searching old threads:
http://www.quiltingboard.com/main-f1...s-t226002.html
However, before using hydrogen peroxide on fabric, be sure to read this thread on the QB:
http://www.quiltingboard.com/main-f1...g-t257130.html
and read what happened to Leah Day's quilt.
Personally, I don't think there is anything you can do to remove a scorch mark. Think about it. The scorch mark consists of burned fabric. Burned fabric is damaged fabric. Anything you do to try to remove the color of the burn will simply weaken the fabric even more. Using scorched fabric in a quilt will mean that years down the line there will be a hole in the quilt where the scorched fabric used to be. I wouldn't use the fabric or would at least find a way to cover up the scorched area -- say, with a piece made out of the same fabric hand appliqued over the damaged spot.