Saliva vs. starch
Learn how saliva helps our bodies digest food!
Warning! Only under adult supervision
- cold water;
- warm water;
- hot water;
- glasses (200 mL / ½ pint);
- 2 teaspoons of saliva;
- iodine solution (antiseptic);
Mix small amounts of starch and cold water, then add hot water to get a volume of about 200 mL / ½ pint. Pour 2 tablespoons of the prepared solution into two glasses and dilute with warm water to 200 mL / ½ pint. Add 2 teaspoons of saliva to one of the glasses, stir, and leave for 1 hour. Then drip some iodine solution (antiseptic) into each glass and observe that the solution in the glass without saliva turns blue.
Saliva is a clear liquid that is slightly more viscous than water. It is secreted by the salivary glands in the mouth. Saliva moistens food and starts the process of its digestion due to the enzymes contained in it, such as amylase. Amylase is an enzyme that breaks down long starch chains into smaller ones. This process can be demonstrated simply and clearly by adding some saliva to a starch solution in water. After a while (about 1 hour), the amylase contained in the saliva will destroy all of the starch, and adding an iodine solution will not turn the solution blue: the blue complex compound of starch with iodine will not form.
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