Mastication or chewing's the process by which food's crushed and ground by teeth. It's the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food's positioned between the teeth for grinding by the cheek and tongue. As chewing continues, the food's made softer and warmer, and the enzymes in saliva begin to break down carbohydrates in the food. After chewing, the food (now called a bolus)'s swallow… (More on Chewing)