Pressurised hot water extraction of acetylated xylan from birch sawdust

Petri Kilpeläinen*, Kaisu Leppänen, Peter Spetz, Veikko Kitunen, Hannu Ilvesniemi, Andrey Pranovich, Stefan Willför

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

38 Citations (Scopus)


Birch sawdust was extracted using pressurized hot water (PHW), with the ultimate aim of maximizing the yield of large and intact non-cellulosic heteropolysaccharides, i.e. hemicellulose molecules. The extractions were performed using a flow-through vessel. Effects of different extraction temperatures between 140 and 200°C were evaluated. The amount of extracted xylans, as well as mono-saccharides, increased as the temperature rose to 190°C, accordingly the degree of polymerization of the xylans decreased. The extracted xylans retained most of the native acetyl groups and were thereby water-soluble after the extraction. The PHW extract contained not only xylan and other hemicellulose-derived oligomers, but fragmented lignin molecules and some extractives as well. Only trace amounts of furfurals were found in the extract at lower extraction temperatures. An optimal yield of water-soluble, polymeric xylans with the smallest amount of unwanted impurities and degradation products was thus achieved at an extraction temperature of 180°C using the flow-through vessel.

Original languageEnglish
Pages (from-to)680-688
Number of pages9
JournalNordic Pulp and Paper Research Journal
Issue number4
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed


  • Acetyl groups
  • Birch
  • Flow-through
  • Hardwood
  • Hemicelluloses
  • Pressurised hot water extraction
  • Xylan


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