Fractional and structural characterization of hemicelluloses from perennial ryegrass (Lolium perenne) and cocksfoot grass (Dactylis glomerata).
Sequential three-stage treatments with 80% EtOH containing 0.2% NaOH, 2.5% H2O2-0.2% EDTA containing 1.5% NaOH and 2.5% H2O2-0.2% TAED containing 1.0% NaOH at 75 degrees C for 3h released 8.0% and 10.4%, 79.1% and 77.0% and 12.9% and 12.5% of the original hemicelluloses from perennial grass and cocksfoot grass, respectively. It was found that the four alkaline peroxide-soluble hemicellulosic fractions contained higher amounts of xylose (33.4-38.2%), uronic acids (9.3-15.3%) and rhamnose (3.0-3.9%), but were lower in glucose (25.1-28.3%), galactose (13.3-15.3%) and mannose (0.4-1.5%) than those of the two alkaline EtOH-soluble hemicellulosic fractions in which glucose (32.9-36.0%), xylose (20.1-22.6%), arabinose (14.1-21.4%), galactose (16.6-19.9%), mannose (4.1-9.9%) and uronic acids (3.4-7.4%) were the major sugar components. 13C NMR spectroscopy confirmed that all the six hemicellulosic fractions were composed of galactoarabinoxylans, 4-O-methylglucuronoarabinoxylans and beta-glucan. In addition, the studies showed that the four alkaline peroxide-soluble hemicellulosic fractions were more linear and acidic and had larger molecular weights (Mw, 28,400-38,650 g mol(-1)) than those of the two alkaline EtOH-soluble hemicellulosic fractions (Mw, 16,460-17,420 g mol(-1)).
Xu
F
F
College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
Geng
Z C
ZC
Sun
J X
JX
Liu
C F
CF
Ren
J L
JL
Sun
R C
RC
Fowler
P
P
Baird
M S
MS
D005591:Chemical Fractionation / Q000379:methods*; D031745:Dactylis / Q000737:chemistry*; D005690:Galactose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D008129:Lolium / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008358:Mannose / Q000737:chemistry; D010545:Peroxides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification; D012210:Rhamnose / Q000737:chemistry; D014574:Uronic Acids / Q000737:chemistry; D014994:Xylose / Q000737:chemistry
D010545:Peroxides; D011134:Polysaccharides; D014574:Uronic Acids; C007916:hemicellulose; D014994:Xylose; D005947:Glucose; D008358:Mannose; D012210:Rhamnose; D005690:Galactose