Chemical digestion is the process through which the body of a mammal reduces food to a size where the nutrients that it contains can be absorbed into the bloodstream. The process begins in the mouth, continues in the stomach and ends when the digested particles move through the small intestine for absorption.Proteins in the mouth, stomach and intestine called enzymes are the primary facilitators of chemical digestion.he process begins in the mouth, continues in the stomach and ends when the digested particles move through the small intestine for absorption. Proteins in the mouth, stomach and intestine called enzymes are the primary facilitators of chemical digestion.