XYLAN

Description

Cellulose1, hemicellulose2 (also called polyose), and lignin3 are the three types of molecules that form the lignocellulosic fibers of plants. Cellulose, a polysaccharide that consists of d-glucose units, was the Molecule of the Week for January 19, 2009. Lignin, with its aromatic polyether structure, was the MOTW for June 25, 2012.
The third type, hemicellulose, is a less ordered, more labile form of cellulose. It also is a polysaccharide, but its various forms can contain six-carbon sugars (hexoses), five-carbon sugars (pentoses), or both. After cellulose and lignin, hemicellulose is the third most abundant biopolymer on Earth. The most common hemicelluloses are glucuronoxylan, arabinoxylan, glucomannan, xyloglucan, and xylan, described here.
Xylan, as its more descriptive name poly(β-d-xylopyranose[1→4]) suggests, is composed primarily of five-carbon xylose units. It is commonly found in the cell walls of grasses and dicotyledon flowering plants. It is the major hemicellulose in cereals and hardwood, which also contain arabinoxylans and glucuronoxylans, respectively. The image shows the structure of the repeating unit of xylan in hardwood.
Xylan and other hemicelluloses derived from agricultural waste are renewable substances used to manufacture chemicals, packaging materials, and biomedical products. The hemicellulose xylan should not be confused with the trade name Xylan, a fluoropolymer coating used in nonstick cookware.
1. CAS Reg. No. 9004-34-6. 2. CAS Reg. No. 9034-32-6. 3. CAS Reg. No. 9005-53-2.

Chemical properties

beige powder

The Uses of XYLAN

Xylan is a major constituent of the secondary cell wall and plant cell-wall polysaccharides. Xylan is also used in the studies involving structural properties, foaming as a new means for food structuring in plants. Xylanases an enzymatic form of xylan is used in several biotechnological processes, primarily for biopulping and biobleaching in the paper industry and as accessory enzymes for bioethanol production.