The enzyme in saliva that breaks down starch is called amylase, specifically salivary amylase.

When salivary amylase acts on starch, it produces maltose. Maltose is a disaccharide, meaning it's made up of two sugar molecules, in this case, two glucose molecules.

So, the breakdown of starch by salivary amylase can be summarized as:

Starch + Water → Maltose