How about test for starch

Here's what happens:

1. Reagent: A few drops of iodine solution (which is typically yellowish-brown or orange-brown) are added directly to the food sample.
2. Reaction: If starch is present, the iodine molecules get trapped within the coiled structure of the starch polysaccharide. This interaction causes a change in the way light is absorbed and reflected.
3. Observation: A distinct blue-black or dark purple color indicates the presence of starch. If no starch is present, the iodine solution will remain its original yellowish-brown color.