The small pieces of food get mixed with saliva by chewing is called a bolus.
When food enters the digestive system by the mouth, it encounters a breakdown by the dental apertures and is then subjected to mixing with saliva which contains the amylase enzyme.
The food along with amylase from the saliva is called the bolus. the bolus is swallowed and travels down the esophagus to the stomach for digestion. This bolus enters the esophagus and from there to the stomach and the intestines. When you chew your food, it gets broken down into smaller pieces that are easier to digest.