1. Structural Characterization of the Milled-Wood Lignin Isolated from Sweet Orange Tree (Citrus sinensis) Pruning Residue
- Author
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Mario J. Rosado, Jorge Rencoret, Ana Gutiérrez, José C. del Río, Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), Junta de Andalucía, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Rosado, Mario J., Rencoret, Jorge, Gutiérrez Suárez, Ana, and Río Andrade, José Carlos del
- Subjects
orange tree pruning ,lignocellulose ,milled-wood lignin ,2D-NMR ,pyrolysis ,Polymers and Plastics ,Orange tree pruning ,General Chemistry ,Milled-wood lignin ,Lignocellulose ,Pyrolysis - Abstract
12 páginas.- 2 figuras.- 4 tablas.- 29 referencias, The pruning of sweet orange trees (Citrus sinensis) generates large amounts of lignocellulosic residue. Orange tree pruning (OTP) residue presents a significant lignin content (21.2%). However, there are no previous studies describing the structure of the native lignin in OTPs. In the present work, the “milled-wood lignin” (MWL) was extracted from OTPs and examined in detail via gel permeation chromatography (GPC), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and two-dimensional nuclear magnetic resonance (2D-NMR). The results indicated that the OTP-MWL was mainly composed of guaiacyl (G) units, followed by syringyl (S) units and minor amounts of p-hydroxyphenyl (H) units (H:G:S composition of 1:62:37). The predominance of G-units had a strong influence on the abundance of the different linkages; therefore, although the most abundant linkages were β–O–4′ alkyl–aryl ethers (70% of total lignin linkages), the lignin also contained significant amounts of phenylcoumarans (15%) and resinols (9%), as well as other condensed linkages such as dibenzodioxocins (3%) and spirodienones (3%). The significant content of condensed linkages will make this lignocellulosic residue more recalcitrant to delignification than other hardwoods with lower content of these linkages., This research was funded by MCIN/AEI/ 10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe” (projects AGL2017-83036-R and PID2020-118968RB-I00) and the Regional Andalusian Government/FEDER (project P20_00017). M.J.R. acknowledges the Spanish Ministry of Science, Innovation and Universities for an FPI fellowship (PRE2018-083267).
- Published
- 2023