bolus (digestion) bolus (digestion) in digestion, a bolus (from latin bolus, "ball") is a ball-like mixture of food and saliva that forms in the mouth during the process of chewing (which is largely an adaptation for plant-eating mammals). it has the same color as the food being eaten, and the saliva gives it an alkaline ph. this bolus from an albatross has several ingested flotsam items, including monofilament from fishing nets and a discarded toothbrush. tern island, french frigate shoals under normal circumstances, the bolus is swallowed, and travels down the esophagus to the stomach for digestion.