| 释义 |
hemicellulose|hɛmɪˈsɛljuːləʊs|
[a. G. hemicellulose (E. Schulze 1891, in Ber. d. Deut. Chem. Ges. XXIV. 2286), f. hemi- + cellulose n.]
Any of various non-cellulosic polysaccharides, of simpler composition than cellulose, that are major constituents of the cell walls of many plants and are characterized by undergoing hydrolysis by acids more readily than cellulose to give a variety of simple sugars and other carbohydrates and by being extractable with dilute alkaline solutions.
1891Jrnl. Chem. Soc. LX. 1179 Those constituents of the cell which dissolve easily in dilute mineral acids, with formation of glucose, he [sc. E. Schulze] calls hemicelluloses. 1921A. L. Smith Lichens v. 212 In Cladonia rangiferina..the cell-membranes of the hyphae contained, as hemicelluloses, pentosans in small quantities and galactan. 1948New Biol. IV. 87 Interspersed in the meshes of the cellulose, which constitutes approximately 50 per cent of the weight of the dry wood, are a number of other substances which apparently serve to stiffen the framework, principally hemicelluloses..and the more complex carbohydrate lignin. 1963R. R. A. Higham Handbk. Papermaking ii. 33 Hemi-celluloses are found in two main groups, i.e., those associated mainly with the plant cellulose and centred largely in the structure of the fibre and those associated with lignin, in the middle lamella and primary walls of fibres. Ibid., The presence of hemi-celluloses in papermaking pulps is very important, as they assist in internal fibrillation of the fibres, but owing to their short chain structure they easily become broken down during digestion and are lost in the form of by-products. |