Re: I did a science project using a starch solution and iodine to test for the

Analysis of Ascorbic Acid or Vitamin C usually involves oxidation by a 
redox dye which in your method's case was iodine.  This method measures the 
 amount of Vitamin C that is avaliable to be reduced. This method only 
measures some forms of Vitamin C and not all of them so you will only get a 
measure of some of the Vitamin C in the food.  There are more complex 
methods used to day for research and by the food companies to tell the 
consumer exactly how much vitamin C is found in fruit juices.  I work with 
an HPLC  (High Performance Liquid Chromatography method).  This method 
measures all the forms of Vitamin C that are used by the body for this 
vitamin.  Usually, people don't realize that when we talk about vitamins we 
are talking about several chemicals that are used by the body for Vitamin 
C.   (The different forms are: Ascorbic Acid, Isoascorbic Acid, 
Dehydro-L-Ascorbic Acid, and Dehydro-D-Isoascorbic Acid) I am sure that 
your method only measured the AA form.  

The procedure that I am more familiar with is a reaction that appears to be 
the reverse of what happened in your reaction.  A dye 
(2,6-Dichloropenol-indopenol) which is blue is actuallyreduced by 
Ascorbic Acid (AA) to a colorless form with more Ascorbic Acid.