The primary enzymes found in saliva are amylase, lysozyme, lingual lipase, and kallikrein. There are several others found in smaller amounts, but these enzymes highlight the main digestive and antibacterial functions of saliva.
Amylase initiates the digestion of long chains of sugars found in bread and crackers known as starches into smaller maltose sugar molecules. Because amylase functions best in slightly basic to neutral pH environments, it cannot work in the acidic stomach and must act in the mouth and esophagus. Lingual lipase is one of the lipase enzymes that break down fats and is specifically associated with triacylglycerols such as the ones found in milk. It is more commonly found in infants and is less common as humans age.
Kallikrein is found in trace amounts in saliva and is responsible for breaking down specific high molecular weight proteins into bradykinin. Although it is found in trace amounts in the saliva, changes in kallikrein levels have been linked to illness, including certain cancers. Lysozyme doesn't aid in digestion. Instead, it protects against illness by breaking down the polysaccharide sugars found in the cell walls of harmful bacteria. This breakdown causes the bacterium to swell and burst in a process known as lysis.