It is found that the first step with mild dioxane extraction resulted
the dissolution of substantial polysaccharides and lignin from
the primary cell wall and middle lamella, and both acidic diox-
ane and DMSO treatments produced original hemicelluloses and
high-condensed lignin mainly from the middle lamella, and alkali
treatment resulted in the removal of residual hemicelluloses and
lignin from the secondary cell wall.
By the analysis of the lignin and hemicellulosic fractions, impor-
tant structural features and relationships between lignin and
hemicellulose are also obtained. Hemicelluloses of barley straw
contain acidic arabinoxylans as the major polysaccharides, which
are substituted by -l-arabinofuranose, 4-O-methyl-d-glucuronic
acid, acetyl group (DS = 0.13), and xylose at O-3 and/or O-2 of xylan.
Lignin contains -O-4
as a predominant interunit linkage with
high amounts of -5
and -1
. The guaiacyl and syringyl units are
more etherified, and the proportion of erythro--O-4
is slightly
It is found that the first step with mild dioxane extraction resultedthe dissolution of substantial polysaccharides and lignin fromthe primary cell wall and middle lamella, and both acidic diox-ane and DMSO treatments produced original hemicelluloses andhigh-condensed lignin mainly from the middle lamella, and alkalitreatment resulted in the removal of residual hemicelluloses andlignin from the secondary cell wall.By the analysis of the lignin and hemicellulosic fractions, impor-tant structural features and relationships between lignin andhemicellulose are also obtained. Hemicelluloses of barley strawcontain acidic arabinoxylans as the major polysaccharides, whichare substituted by -l-arabinofuranose, 4-O-methyl-d-glucuronicacid, acetyl group (DS = 0.13), and xylose at O-3 and/or O-2 of xylan.Lignin contains -O-4as a predominant interunit linkage withhigh amounts of -5and -1. The guaiacyl and syringyl units aremore etherified, and the proportion of erythro--O-4is slightly
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