Fractional isolation and structural characterization of hemicellulosic polymers from Caragana sinica

Abstract

The cell wall material of Caragana sinica was fractionated by successive extractions with distilled water at 80 °C for 2 h, 70% ethanol, 70% ethanol containing 1% NaOH, 1 M KOH, 1 M NaOH, 3 M KOH, and 3 M NaOH at 75 °C for 3 h. The sequential treatments resulted in a total dissolution of 86.7% of the original hemicelluloses and 80.1% of the original lignin from dewaxed C. sinica. The current results showed that the four alkali-soluble hemicellulosic preparations, comprising almost 80% xylose of the total neutral sugars, were more linear and acidic, but lower molecular weights ( w , 28420-55140 g/mol) than the other two organosolv-soluble hemicelluloses ( w , 57930-96470 g/mol). The 1 M KOH-soluble hemicellulosic fraction was characterized by sugar analysis and 1D, 2D NMR spectroscopy and was found to be composed of a linear (1→4)-β-D-xylopyranosyl main chain with a 4-Omethylglucuronic acid substituting the C-2 position of approximately every eight xylose unit, which is typical of a hardwood acidic 4-O-methylglucuronoxylan (MGX).

Review on Polysaccharides Used in Coatings for Food Packaging Papers

“…Moreover, it has been reported that the addition of ethanol in alkaline solution can break the resistance of the cell wall of the plant [80].…”