The enzyme that breaks down starch is amylase. Starch is a type of complex carbohydrate made by plants and consists of glucose subunits. Amylase breaks starch into constituent sugar molecules.
Depending on the type of amylase, the starch can be broken down into either compound sugars, such as maltose, or simple sugars, such as glucose and fructose.
The first amylase starch encounters is the salivary amylase. The teeth break food up into smaller pieces. The act of chewing stimulates the release of amylase from the salivary glands in the mouth, as amylase is present in human saliva. This form of amylase does not break starch down completely but rather breaks it down into the disaccharide maltose. The pancreas also contains amylase that changes starch to maltose. In the small intestine, maltase then breaks down maltose into two glucose molecules.