Question

What experiment should you perform to understand action of saliva on flour? Explain it's procedure and opparatus that you followed.

Answer 1

To test the action of saliva on flour, Amylase test is conducted.

Procedure:

• Add a pinch of flour to a test tube half filled with water, mix it properly.
• Add a few drops of iodine solution to the mixture.
• If the solution turns blue, then the presence of starch in the flour is confirmed.
• Again add a pinch of flour to a test tube filled half with water, mix it properly and divide the mixture into two parts by transferring it to another test tube.
• Two one of the test tube, add a few drops of saliva and leave it for 30 to 45 minutes.
• Add iodine solution into both the test tubes.
• It is observed that the solution with saliva in it does not turn blue, whereas the solution without saliva turns blue.

The starch present in the flour traps the iodine inside its structure and hence blue colour is observed. Saliva has amylase enzyme in it which dissolves starch to simpler sugars and hence the solution with saliva in it could not show blue colour due to lack of starch.