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High temperature aqueous treatment of wood is the preferred technology for deconstructing lignocellulosics. Many studies have been carried out on the kinetics and mechanism of hot-water extraction. ...

The effect of hot-water extraction and two types of fungal decay, brown rot and white rot, on wood crystalline cellulose structure was examined using a combination of X-ray diffraction (XRD) and 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. Although having opposite effects on the overall crystallinity of the wood, the XRD results revealed that both extraction and brown-rot decay caused a significant decrease in the 200 crystal plane spacing (d-spacing) not seen for the white-rotted samples. This effect was found to be additive, as samples that were first extracted, then decayed showed a double decrease in d-spacing compared to that caused by extraction alone. This suggested that, despite having a similarly directed effect on the spacing of the crystalline planes, the two treatment methods facilitate a decrease in d-spacing in different ways. NMR results support the conclusion of differing structural effects, suggesting that the hot-water extraction procedure was causing a co-crystallization of existing crystalline domains, while the brown rot decay was depolymerizing the cellulose chains of the crystals, possibly allowing the remaining crystalline material the freedom to relax into a more energetically favorable, tightly packed state. These findings could have important implications for those seeking to understand the effects of modification treatments or biodegradation of crystalline cellulose nanostructures in their native states.

Cell walls polysaccharides from murta fruit (Ugni molinae Turcz), an endemic Chilean species with relevant food uses, were fractionated by water, ammonium oxalate, hot diluted HCl and cold diluted NaOH extractions. The polysaccharide fractions were analysed for monosaccharide composition and physicochemical properties. Pectic substances were found in all extracts, but mainly in the oxalate and acid soluble fractions, in which they appear as homogalacturonan polymers. Murta pectin was further extracted by hot diluted acid treatment using industrial conditions, yielding 30% by weight of dry fruit. The polymer showed similar composition and physicochemical properties to those of commercial citrus pectin, presenting a galacturonic acid content of 70.9% (w/w), a molecular weight of 597. kDa, and a methoxylation degree of 57%. The FT-IR spectrum of murta pectin suggests the presence of ferulic acid residues on its structure and the NMR analysis confirmed the structure of this polysaccharide. It is concluded that murta fruit can be considered as a valuable source of high quality pectin.

Hardwood hemicellulose extracts can be used as a feed stock for ethanol plants or for renewable polymer applications. Extraction of Acer rubrum wood strands with water at 160°C and for 90 minutes removed approximately 16% of the wood weight. The extract was composed primarily of acetylated glucuronoxylans (63.9%) and lignin (17.6%). The dispersive surface energy and acid-base surface characteristics for a multi-component freeze dried mixture of hot water extracted Acer rubrum components was determined by inverse gas chromatography (IGC). The dispersive surface energy of the extract was found to be non-sensitive to thermal variations and has a magnitude of 34.6 ± 0.2 mJ/m2 with a K a of 0.13 and K b of 0.46. The maple wood had a regressed surface energy of 42.7 mJ/m2 at 20°C following extraction, and the surface energy before extraction was 40.4 mJ/m2 at 20°C. Also, before extraction the K a and K b of the red maple were 0.19, 0.92, respectively, and after extraction the K a and K b were 0.15 and ...