Wheat straw lignin fractionation and characterization as lignin-carbohydrate complexes
2016 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 85, 309-317 p.Article in journal (Refereed) PublishedText
Alkaline extracted and untreated wheat straw were ball-milled with liquid nitrogen cooling rendering them completely soluble in the solvent system dimethylsulfoxide-aqueous tetrabutylammonium hydroxide for subsequent fractionation into two lignin-carbohydrate complex fractions termed glucan-lignin and xylan-lignin according to their preferred association with glucan or arabinoxylan, respectively. This is the first description using this fractionation protocol for wheat straw. Eventually, acidolysis lignins were prepared from both lignin-carbohydrate complexes and structurally characterized using wet chemistry and NMR spectroscopy methods. Using the novel procedure we could reveal differences regarding wheat straw lignin association with polysaccharides, p-hydroxycinnamic acids and tricin as well as in their monomer composition. In glucan-lignin the lignin moiety was found to be linked mainly to glucan but also to branched arabinoxylan. Xylan-lignin, however, was rich in structures creating cross-links between lignin and linear arabinoxylan via ether-ester bridges by bi-functional ferulic acid. Inter-molecular ether-ester-linkages by ferulic acid connecting the lignin moieties of the two LCC fractions glucan-lignin and xylan-lignin were proposed. Alkaline extraction of the straw resulted in a strikingly lower recovery of xylan-lignin in the subsequent fractionation which was attributed to cleavage of ester linkages between ferulic acid and arabinoxylan. Structural characteristics indicated glucan-lignin and xylan-lignin deriving from different morphological origins of the cell wall.
Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 85, 309-317 p.
Arabinoxylan, Lignin, Lignin-carbohydrate complexes, NMR spectroscopy, Wheat straw, Alkalinity, Carbohydrates, Esters, Ethers, Nuclear magnetic resonance spectroscopy, Spectroscopic analysis, Straw, Arabinoxylans, Lignin-carbohydrate complex, Liquid-nitrogen cooling, Monomer compositions, p-Hydroxycinnamic acids, Structural characteristics, Tetrabutylammonium hydroxides, Wheat straws, Triticum aestivum
IdentifiersURN: urn:nbn:se:kth:diva-186911DOI: 10.1016/j.indcrop.2016.03.012ISI: 000374361100034ScopusID: 2-s2.0-84962559648OAI: oai:DiVA.org:kth-186911DiVA: diva2:931282
QC 201605272016-05-272016-05-162016-06-09Bibliographically approved