How can we test the presence of starch in food?

The presence of starch in food can be tested using the iodine test. Place a small amount of the food sample on a plate or in a test tube and add 2-3 drops of iodine solution.

If the food contains starch, the iodine solution changes from brown or yellow-brown to blue-black. If there is no starch, the iodine solution remains its original colour. This simple test is commonly performed in school science laboratories to identify starch in foods such as potatoes, rice, and bread.