Sulfite pulp from xylan

Bleached, soda pulp contained about the same amount of resistant xylan as bleached, sulfate pulp, and a bleached, sulfite pulp contained only a small amount (Table X). In this same study," it was observed that the resistant-xylan content was greater in an air-dried or oven-dried pulp than in the same pulp before drying (see Table XI). In agreement with the work of Meller," a reduction in resistant xylan resulted from mechanical beating or grinding. 

The recent studies of the Finnish group further emphasize the complexity of the xylan in wood cellulose. These workers have shown that the properties of the xylan in wood pulps depend not only on the method of pulping but also on the type of raw material. It was observed that, when pulps are prepared by the (acidic) sulfite process from the softwoods, pine and spruce, a substantial part of the xylan is of the acidic type (see Fig. 2, p. 303). Even when these sulfite pulps are refined further with hot alkali, some acidic xylan remains. However, when pulps are prepared from pine and spruce by the (alkaline) sulfate process, the acidic xylan is removed and only neutral xylan remains. 

Immergut and R8.nby have resolved a mixture of a xylan and a gluco-mannan from a spruce sulfite pulp by a series of alkaline extractions and... 

Binding of xylanase components shake flasks by SF, has been carried out on sulfite pulps (8). Although xylanases from A. oryzae has been produced exclusively in SF (4,8,14,31), a SSF alternative has been demonstrated most recently (IS). However, no reports are found in flie iit ture on the use of xylanase enzymes produced by this fringus in SSF for biobleaching of cellulose pulps. 

Figure IL The SEC molar mass distribution curves for arabino-4-O-methyl-glucuronoxylan (from spruce holocellulose), arabinohexenuronoxylan (kraft pulp) and two different 4 0-methylglucuronoxylans (sulfite and dissolving pulp) obtained by the SEC/MALDI-MS procedure. Each xylan was analyzed separately employing the alkaline (pH 13) buffer SEC system and subsequently graphed on the same MALDI-MS calibrated absolute molar mass scale.

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