title: Isolation and characterization of acetylated glucuronoarabinoxylan from sugarcane bagasse and straw.
abstract: Sugarcane bagasse and straw are generated in large volumes as by-products of agro-industrial production. They are an emerging valuable resource for the generation of hemicellulose-based materials and products, since they contain significant quantities of xylans (often twice as much as in hardwoods). Heteroxylans (yields of ca 20% based on xylose content in sugarcane bagasse and straw) were successfully isolated and purified using mild delignification followed by dimethyl sulfoxide (DMSO) extraction. Delignification with peracetic acid (PAA) was more efficient than traditional sodium chlorite (NaClO2) delignification for xylan extraction from both biomasses, resulting in higher extraction yields and purity. We have shown that the heteroxylans isolated from sugarcane bagasse and straw are acetylated glucuronoarabinoxylans (GAX), with distinct molecular structures. Bagasse GAX had a slightly lower glycosyl substitution molar ratio of Araf to Xylp to (0.5:10) and (4-O-Me)GlpA to Xylp (0.1:10) than GAX from straw (0.8:10 and 0.1:10 respectively), but a higher degree of acetylation (0.33 and 0.10, respectively). A higher frequency of acetyl groups substitution at position α-(1→3) (Xyl-3Ac) than at position α-(1→2) (Xyl-2Ac) was confirmed for both bagasse and straw GAX, with a minor ratio of diacetylation (Xyl-2,3Ac). The size and molecular weight distributions for the acetylated GAX extracted from the sugarcane bagasse and straw were analyzed using multiple-detection size-exclusion chromatography (SEC-DRI-MALLS). Light scattering data provided absolute molar mass values for acetylated GAX with higher average values than did standard calibration. Moreover, the data highlighted differences in the molar mass distributions between the two isolation methods for both types of sugarcane GAX, which can be correlated with the different Araf and acetyl substitution patterns. We have developed an empirical model for the molecular structure of acetylated GAX extracted from sugarcane bagasse and straw with PAA/DMSO through the integration of results obtained from glycosidic linkage analysis,1H NMR spectroscopy and acetyl quantification. This knowledge of the structure of xylans in sugarcane bagasse and straw will provide a better understanding of the isolation-structure-properties relationship of these biopolymers and, ultimately, create new possibilities for the use of sugarcane xylan in high-value applications, such as biochemicals and bio-based materials.
authors.affiliation: Pulp and Paper Laboratory, Department of Forestry Engineering, Federal University of Viçosa, Av. P. H. Rolfs, S/N, Campus, 36570-900 Viçosa, Minas Gerais, Brazil; Department of Fibre and Polymer Technology, KTH, Royal Institute of Technology, Teknikringen 56-58, SE-100 44 Stockholm, Sweden.
authors.forename: Danila
authors.initials: D
authors.lastname: Morais de Carvalho
authors.affiliation: Division of Glycoscience, School of Biotechnology, KTH, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm, Sweden.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Abad
authors.affiliation: CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Evtuguin
authors.affiliation: Pulp and Paper Laboratory, Department of Forestry Engineering, Federal University of Viçosa, Av. P. H. Rolfs, S/N, Campus, 36570-900 Viçosa, Minas Gerais, Brazil.
authors.forename: Jorge Luiz
authors.initials: JL
authors.lastname: Colodette
authors.affiliation: Department of Fibre and Polymer Technology, KTH, Royal Institute of Technology, Teknikringen 56-58, SE-100 44 Stockholm, Sweden.
authors.forename: Mikael E
authors.initials: ME
authors.lastname: Lindström
authors.affiliation: Division of Glycoscience, School of Biotechnology, KTH, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm, Sweden; Wallenberg Wood Science Center, Department of Fibre and Polymer Technology, KTH, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Electronic address: franvila@kth.se.
authors.forename: Francisco
authors.initials: F
authors.lastname: Vilaplana
authors.affiliation: Department of Fibre and Polymer Technology, KTH, Royal Institute of Technology, Teknikringen 56-58, SE-100 44 Stockholm, Sweden; Wallenberg Wood Science Center, Department of Fibre and Polymer Technology, KTH, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Electronic address: olena@kth.se.
authors.forename: Olena
authors.initials: O
authors.lastname: Sevastyanova
mesh_terms: D000107:Acetylation; D002482:Cellulose / Q000737:chemistry*; D031786:Saccharum / Q000737:chemistry; D014990:Xylans / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D014990:Xylans; C114470:glucuronoarabinoxylan; D002482:Cellulose; C027433:bagasse
keywords: (1)H NMR spectroscopy; Acetylated xylan; Arabinoxylan; Linkage analysis; Sugarcane bagasse; Sugarcane straw