Bolus is the food that is mashed up in your mouth. After it is digested in the stomach, the food is called chyme. 
Bolus is more alkaline than chyme because it is exposed to alkaline saliva. Teeth and saliva turn food into bolus. It is then swallowed and passes through the esophagus into the stomach. 

Chyme has a higher acidity content than bolus because it was exposed to hydrochloric acid in the stomach. Chyme enters the small intestine after digestion in the stomach.
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