According to ScienceDaily.com, saliva is the watery and usually somewhat frothy substance produced in the mouths of some animals, including humans. Produced in salivary glands, saliva is 98% water, but it contains many important substances including electrolytes, mucus, antibacterial compounds and various enzymes.

The digestive functions of saliva include moistening food and helping to create a food bolus, so it can be swallowed easily.

Saliva contains the enzyme amylase that breaks some starches down into maltose and dextrin.

Thus, digestion of food occurs within the mouth, even before food reaches the stomach.