The majority of carbohydrate digestion occurs in the small intestine. It is here that disaccharides (sugars composed of two monosaccharides) like sucrose, maltose, and lactose are broken down into monosaccharides, which are then absorbed directly into the cells that form the intestinal lining.igestion of starch begins in the mouth with the chewing of food (mastication) and the production of amylases immediately breaking down certain starches.