The Structural, Molecular and Functional Properties of Lignin‐Containing Beechwood Glucuronoxylan

Abstract

ummary: The samples of 4-O-methyl-D-glucurono-D-xylan (GX) with different lignin and uronic acid (MeUA) contents were prepared from beechwood by various procedures. The re-dissolution process of the partially water-soluble GX-2 lyophilizate in aqueous medium depended on the content and distribution of MeUA. In contrast to the supernatant after ultracentrifugation, the sediment had a significantly lower MeUA content and showed mainly high-molecular mass components. A part of lignin degradation products is separable by repeated dissolution and precipitation of GX in acidic and alkaline 80% ethanolic media with assistance of ultrasound. Irradiation in acidic ethanol (GX-3/ac) showed no effect on the distribution of the UV 254 -absorbing component. GX-3 sonicated in neutral and alkaline media (GX-3/ne, GX-3/alk) lost water solubility. The lignin-rich GX samples showed remarkable emulsifying efficiency and protein foam stabilization effect. In addition, the presence of phenolics provided antioxidant properties to these xylan preparations indicating their potential as polymeric radical scavengers.

Synthesis and Characterization of Hydrophobically Modified Xylans

“…From the SEC data, the xylan samples appeared to contain two components with different molecular weights. In the literature, some xylan samples were indeed reported to contain more than one molecular weight component [ 53 , 74 , 75 , 76 ]. It is noteworthy that there was no significant changes in molecular weight due to the derivatization reactions.…”

Strategies for structuring diverse emulsion systems by using wood lignocellulose-derived stabilizers

“…94 In addition to surface activity and the physical capacity to stabilize emulsions, phenolic compounds such as lignin fragments introduce antioxidant properties to hemicelluloses. 60,61,91,95 This was shown by Wrigstedt et al, who synthesized ferulic acid and sinapic acid esters on birch GX and testing the antioxidant and emulsification properties. 96 In a different study, spruce GGM containing phenolic residues efficiently inhibited lipid oxidation of rapeseed oil o/w emulsions, as indicated by the resulting peroxide values, volatile oxidation products, and analysis of polymerized lipids.…”

“…12 For example, native beech GX isolates that contained residual lignin showed the capacity to stabilize emulsions. 91 In addition, spruce GGM extracts often contain varying amounts of lignin residues, 61 and they have been shown to stabilize colloidal wood resin emulsions 92 as well as orange o/w emulsions. 93 Furthermore, GGM adsorbed at the rapeseed o/w emulsion droplet interface and stabilized it.…”

The role of the glucuronoxylan carboxyl groups in the action of endoxylanases of three glycoside hydrolase families: A study with two substrate mutants

“…This band is not visible in the spectrum of glucoxylan, indicating the successful reduction of the ester group.The structural changes indicated by the IR analysis were confirmed 1D-and 2D-NMR spectroscopy techniques. The limited solubility in water of the native glucuronoxylan[25] and further decreased solubility after methyl-esterification, was the reason why DMSO-d 6 was used as a solvent. As NMR spectra of heteroxylans measured in the aprotic solvent are rare and often incompletely assigned, the data interpretation was accomplished in comparison to the chemical shifts of 4-O-methylglucuronoxylan polymers, related synthetic oligosaccharides[26,27], and few other acidic heteroxylans[28][29][30], measured in both D 2 O and DMSO-d6 .…”