Laboratory of Wood and Paper Chemistry, Process Chemistry Centre, Åbo Akademi University, Porthansgatan 3, FI-20500 Turku/Åbo, Finland.
Bioresour Technol. 2013 Feb;130:198-203. doi: 10.1016/j.biortech.2012.11.149. Epub 2012 Dec 10.
Two methods for separation of polymeric galactoglucomannans (GGMs) from a hot-water extract of spruce wood, i.e., membrane filtration and precipitation in ethanol-water, were compared. Filtration through a series of membranes with different pore sizes separated GGMs of different molar masses, from polymers to oligomers. Only polysaccharides were precipitated in ethanol-water. With the optimal water content of 5-15%, the precipitated amount was about 6% on wood basis. The average molar mass of the precipitated polysaccharides was 10-12kDa with a molar mass range of 4-20kDa. GGMs comprised about 80% of the precipitated hemicelluloses. Other precipitated polysaccharides were mainly arabinoglucuronoxylans and pectins (rhamnogalacturonans). Analysis of a lignin-free, ethanol-precipitated GGM preparation by (13)C NMR spectroscopy verified that it was structurally almost identical with a GGM-rich ethanol precipitate obtained from spruce wood by extraction at much milder conditions, 90°C for 60min.
比较了两种从云杉木材热水提取物中分离聚合半乳甘露聚糖（GGM）的方法，即膜过滤和乙醇-水沉淀。通过一系列具有不同孔径的膜过滤可分离不同摩尔质量的 GGM，从聚合物到低聚物。只有多糖在乙醇-水中沉淀。在最佳水含量为 5-15%时，沉淀量约为木材基础的 6%。沉淀多糖的平均摩尔质量为 10-12kDa，摩尔质量范围为 4-20kDa。GGM 约占沉淀半纤维素的 80%。其他沉淀的多糖主要是阿拉伯半乳聚糖醛酸木聚糖和果胶（鼠李半乳糖醛酸聚糖）。通过（13）C NMR 光谱分析无木质素、乙醇沉淀的 GGM 制剂，证实其结构几乎与通过在温和得多的条件（90°C 60min）下从云杉木材提取获得的富含 GGM 的乙醇沉淀相同。
