Digestion of foods in the small intestine. The small intestine continues the process of digestion and various enzymes are present there to break starches down further. These enzymes are called disaccharidases. The best known is lactase, which is the enzyme necessary to digest milk sugar. This enzyme is normally present in all young mammals who need this to digest mother's breast milk. With age and as breast feeding finishes, production of this enzyme ceases for life.