Saliva contains the enzyme amylase, which is capable of breaking down starch into simpler sugars such as maltose and dextrin that can be further broken down in the small intestine. It also moistens the food for easy swallowing.
Saliva is been secreted by the salivary glands present in the mouth. This is very much slippery and it is an enzyme.
When we take in the food the food must enter into oesophagus so this enzyme helps in this process
the taste and smell of food activates three paur of salivary gland which secerete saliva,saliva contain enzyme salivary amylase(ptylin) which convert starch into maltose i.e sugar.hence digestion itself starts in mouth