Amylase

In the mouth, chewing breaks food into smaller pieces, while saliva from the salivary glands contains amylase, which starts digesting starch. Food passes down the oesophagus to the stomach. The stomach produces hydrochloric acid, which kills bacteria and provides acidic conditions for a stomach protease to work.

Amylase is an enzyme that breaks starch down into smaller sugars. The aim of this core practical is to find out how pH affects that breakdown. You cannot easily watch starch molecules disappearing, but you can test samples with iodine: iodine turns blue-black when starch is present and stays yellow-brown when starch is no longer detected.