Microcrystalline cellulose

Microcrystalline cellulose is a term for refined wood pulp and is used as a texturizer, an anti-caking agent, a fat substitute, an emulsifier, an extender, and a bulking agent in food production.^[1] The most common form is used in vitamin supplements or tablets. It is also used in plaque assays for counting viruses, as an alternative to carboxymethylcellulose.^[2]

In many ways, cellulose makes the ideal excipient. A naturally occurring polymer, it is composed of glucose units connected by a 1-4 beta glycosidic bond. These linear cellulose chains are bundled together as microfibril spiralled together in the walls of plant cell. Each microfibril exhibits a high degree of three-dimensional internal bonding resulting in a crystalline structure that is insoluble in water and resistant to reagents. There are, however, relatively weak segments of the microfibril with weaker internal bonding. These are called amorphous regions; some argue that they are more accurately called dislocations, because of the single-phase structure of microfibrils. The crystalline region is isolated to produce microcrystalline cellulose.

Approved within the European Union as a thickener, stabilizer or emulsifiers microcrystalline cellulose was granted the E number E460(ii) with basic cellulose given the number E460 (i) ^[3]

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