Gymnosperms: glucomannans

CeU waUs of woods contain other subgroups of hemiceUuloses, in particular those composed primarily of D-mannopyranosyl or D-galactopyranosyl units. Glucomannans [11078-31-2] comprise 3—5% of the wood of angiosperms and 3—12% of the wood of gymnosperms. Galactoglucomannans [9040-29-3] are also common. 

The predominant hemicelluloses in secondary cell walls of both monocotyledons and dicotyledons are xylans. These polysaccharides have a xylan main chain that is decorated with 4-0-methyl-D-glucopyranosyluronic acid, D-glucopyranosyluronic acid, L-arabinofuranosyl, and/or L-arabinopyranosyl units. These related polysaccharides are usually acetylated to various degrees. Gymnosperms contain glucomannans, also acetylated, as the principal secondary cell-wall hemicellulose [26]. 

Glucomannans are also obtained from seeds or roots the structure is a random arrangement of 4)-j8-Glc-(l and ->4)- -Man-(l. The ratio Glc/Man depends on the source and varies from 1 1 in Iris bulbs to 1 5 in certain gymnosperms. Konjac glucomannan has been developed mainly in Japan for food appUcations... 

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