Will saliva break down starch if boiled?

Starch is not broken down by saliva itself, but by the enzyme amylase, which is secreted along with it.

Enzymes are special proteins that are biological catalysts. In this case, amylase breaks down a complex starch molecule into simpler oligosaccharides. One of the properties of oligosaccharides is a sweet taste, therefore, if you hold a piece of bread in your mouth for a long time, you can feel the sweetness – this amylase has broken down the starch.

Like all proteins, enzymes are susceptible to denaturation at high temperatures. When boiling, irreversible denaturation of the amylase occurs, that is, it will not recover and will lose its activity. Therefore, after boiling saliva, starch will not break down.