Twenty to thirty-five percent of wood mass is hemicellulose. Hemicellulose is a
heterogeneous group of polysaccharides containing 15–200 pentose and hexose
sugars joined by β-(1,4) linkages. The greatest number of these units are xyloses,
thus they are also know as xylans. These structures are the first components of
wood to undergo thermal decomposition during pyrolysis.
定義
hemicellulose: A polysaccharidefound in the cell walls of plants. Thebranched chains of this moleculebind to cellulose microfibrils, forminga network of cross-linked fibres.
农业用途
Hemicellulose is one of the broad complex divisions of polysaccharides (the other being pectin) having a polymerization of 150cellulose molecules or less. It is a collectivet erm for beta and gamma cellulose. Hemicelluloses are alkali-soluble polysaccharides, while pectin is acidic. These polysaccharides as well as cellulose (which is also a polysaccharide) are constituents of a plant cell wall and function to ensure a high mechanical strength and rigidity to the wall. Hemicelluloses sometimes become store houses of nutrition, as in the case of some seeds, for example, date seeds and nasturtium seeds. In the food processing industry, it is a common practice to add special enzymes while processing so that the cell walls therein may be made more soluble and integrated for consumption. An example of this is seen during the production of fruit juice. Hemicellulose is obtained by steam treating a mixture of soft and hard woods, and can be used as an animal feed supplement.
