Digestion of food in vitro
Illustrate the action of amylase on starch.
What you need to know:
- Bread contains starch (a complex carbohydrate);
- Iodine solution is a chemical reagent which only changes colour when starch is present;
- Amylase is an enzyme (present in saliva) which transforms starch into glucose.
Prepare two test tubes with the following mixtures:
- tube 1: bread + iodine solution + water
- tube 2: bread + iodine solution + amylase
Leave for 20 minutes and then observe what has happened:
- The iodine solution in tube 1 has turned blue, showing that it contains starch and that water alone does not transform starch.
- The iodine solution in tube 2 remains yellow, showing that it does not contain any starch and that the amylase has transformed the starch into glucose.