How long does sugar stay in your blood? Digestion is the process of breaking down food into nutritive components that can be absorbed by the bloodstream and delivered to the cells. It begins with the mechanical breakdown of food in the mouth, where smaller food particles then enter the stomach through the esophagus. Chemical digestion through enzymatic action and acidic secretions further hydrolyzes the food in the stomach, which then enters the small intestine after 2 hours.