Hemicelluloses isolation

During the past decade, MALDI-TOF MS has proven to be an effective tool for the analysis of oligo- and polymeric mannoglucans (for extensive reviews see [222,223]). SEC/MALDI mass spectrometry was employed in the analysis of hemicelluloses isolated by microwave heat-fractionation from spruce and aspen wood [94]. These methods allowed the separation and characterization of the oligo- and polysaccharide fractions derived from the xylan and mannan components of both woods [224]. 

The GGM-rich hemicelluloses, isolated from water-impregnated spruce chips by heat-fractionation [218], has been used as pre-polymers after modification with methacrylic functions [439]. Radical polymerization of the modified hemicelullose with 2-hydroxyethyl methacrylate in water yielded elastic, soft, transparent, and easily swollen hydrogels. 

The number of reports about hemicelluloses that have been covered by this review indicates the significantly increased importance of all types of hemicelluloses as plant constituents and isolated polymers during the last decade. Attention has been paid not only to known hemicelluloses but also to the primary structure, physicochemical, physical, and various functional properties of hemicelluloses isolated from hitherto uninvestigated plants. The efforts to exploit a variety of plant as potential sources of hemicelluloses were pointed out particularly for agricultural crops, wood wastes, as well as for by-products of pulp and rayon fiber technologies. Many studies were devoted to characterize seed-storage hemicelluloses from plants that have been traditionally applied in food and medicine of many underdeveloped countries to find substitutes for imported commercial food giuns. 

Further research is directed to the determination of the fine-structure of the pectins and hemicelluloses isolated from soy meal, using chromatography and degradation with specific enzymes. With these results a model of the polysaccharides present in the cell wall of soy will be formulated. Furthermore, application directed experiments will be performed to obtain information about structure-function relationships. 

In a typical hemicellulose isolation process, finely ground plant material (200 g) is treated with 5-10% sodium hydroxide in oxygen-free water at 25°C for 18-24 h (Whistler and Feather, 1965). The water-insoluble fraction, containing two subfractions differentiated by density, is extractable with higher rather than lower NaOH concentrations progressively higher concentrations of alkali extract progressively more of the dense saccharides. 

C12H22O11 342.299 Structural unit in the glucomannans of plant hemicelluloses. Isol. from the partial acid hydrolysates of the glucomannans from Amorphophallus spp., white spruce (Pinus glauca), western hemlock (Tsuga heterophylla), red maple (Acer rubrum), eastern white pine (Pinus strobus), larch (Larix decidua), jack pine (Pinus bank-siana) and from Narcissus tazetta from hemicelluloses of lobolly pine (Pinus taeda) and in trace amounts from the acetolysates of the a-celluloses from white birch (Betula papyrifera) and slash pine... 

C12H22O11 342.299 Structural unit in the glucomannan of plant hemicelluloses. Isol. from partial acid hydrol. of Amorphophalus, spp., Picea glauca, Tsuga heterophylla, Acer rubrum and others. 

The hemicelluloses isolated ly aqueous alkali fixim vdieat straw were, in neral, Inown and this inqiedes their industrial utilization. The aim in our laboratory is to develop a commercial process for fractionation of cereal straw components using an environmental Mendfy xocedure for the extraction of... 

In 1996 we described (1) the successful application of Matrix-Assisted-Laser-Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) for characterizing hemicelluloses isolated from wood and pulps. Since then this approach has been improved considerably (2,3) and several different procedures for wood and pulp constituents have been reported (3-8). In the present article, a selection of our previously reported analytical procedures are discussed together with some hitherto unpublished results from our laboratory. 

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