Fractionation of DMSO-Extracted and NaOH-Extracted Hemicelluloses by Gradient Ethanol Precipitation from Neosinocalamus affinis

Abstract

Neosinocalamus affinis hemicelluloses were extracted with pure DMSO and 3% NaOH in sequence. The DMSO- and NaOH-extracted hemicelluloses were then successively fractionated by gradient ethanol precipitation. NaOH-extracted hemicellulosic fractions with different branch degree could be separated by gradient ethanol precipitation, while DMSO-extracted hemicellulosic fractions could not. FT-IR spectra showed that DMSO-extracted fractions have more complete structure, while NaOH-extracted fractions have no acetyl at all. The FT-IR and NMR revealed that the DMSO-extracted Neosinocalamus affinis hemicelluloses were 4-O-methyl-glucuronoarabinoxylans consisting of a linear (1→4)-β-D-xylopyranosyl backbone with branches at O-2,3 of acetyl, O-2 of 4-O-methyl-a-D glucuronic acid, and O-3 of arabinose.

Properties of Water‐Soluble Xylan from Different Agricultural By‐Products and their Production of Xylooligosaccharides

“…These are usually found in the endosperm and bran of cereal grains; ii) glucuronoarabinoxylansubstituted with ArbF units, acetylized and esterified with ferulic acid, a typical feature of grasses and cereals; iii) heteroxylans are mostly substituted with mono-or oligosaccharides, that are seen in bran and seed of cereals and gum exudates. [3,4] The extraction of xylan can be carried out using alkali, [5,6] dimethyl sulfoxide (DMSO) [7,8] water, [9] hot water under pressure, [10] and cold water under pressure. [11] Water extraction assists in the separation of water-soluble hemicelluloses (xylan) that has high molar mass, less arabinose substitution, and preserves the structure of hemicellulose; however, the yield is low which can be enhanced by pretreatment processes.…”