Cellulose is a complex carbohydrate, or polysaccharide, that is a key structural component of plant cell walls. It is composed of long chains of glucose molecules linked together in a way that makes it indigestible for humans, as we lack the necessary enzymes to break it down. Unlike starches, which store energy in plants and can be digested by humans, cellulose serves a structural role, providing rigidity and strength to plants. While indigestible, cellulose is an important source of dietary fiber, aiding in digestion by promoting healthy bowel movements.
Ruminants, such as cattle and sheep, are able to digest cellulose thanks to the large bacterial colonies that live in their guts.
Cellulose derivatives, with E numbers E461 to E469, are used as emulsifiers, thickeners and stabilizers in processed foods. Cellulose powder is, for example, used in processed cheese to prevent caking inside the package.