Extraction and chemical features of wood hemicelluloses: A review

Hemicelluloses have immense potential for applications in diverse fields, especially in polymeric materials. This review critically examines biomass treatment technologies, encompassing chemical, mechanical, and combined approaches to disrupt plant cell walls and enhance hemicellulose accessibility and solubility. The choice of a treatment method depends on factors like purpose, biomass composition, and economic and environmental considerations. Hemicelluloses extracted from wood are composed from up to 11 monomer units, most of them "neutral" monosaccharides (glucose, mannose etc.) but a couple "charged" (uronic acids). The average compositions of wood hemicelluloses change with the type of wood; the accuracy is not known. The content of "charged" monosaccharides may particularly suffer from underestimation due to strong hydrolysis. The chemical composition of intact wood hemicelluloses has never been determined: it is thus not known if hemicelluloses in wood are a mixture of several "simple" polysaccharides (such as glucomannans) or complex polysaccharides with up to 11 monomer units in the same macromolecule. Currently determined molecular weights (MW) of hemicelluloses range from 500 to 1,000,000 Da. The precision and accuracy of MWs are not known, primarily due to column inconsistency in analyzing anionic and neutral polymers. A combination of chromatography SEC methods and detectors is required for standardization.