BioEnergy Research

, Volume 8, Issue 3, pp 992–1003 | Cite as

Lignin Structural Alterations in Thermochemical Pretreatments with Limited Delignification

  • Yunqiao Pu
  • Fan Hu
  • Fang Huang
  • Arthur J. Ragauskas


Lignocellulosic biomass has a complex and rigid cell wall structure that makes biomass recalcitrant to biological and chemical degradation. Among the three major structural biopolymers (i.e., cellulose, hemicellulose, and lignin) in plant cell walls, lignin is considered the most recalcitrant component and generally plays a negative role in the biochemical conversion of biomass to biofuels. The conversion of biomass to biofuels through a biochemical platform usually requires a pretreatment stage to reduce the recalcitrance. Pretreatment renders compositional and structural changes of biomass with these changes ultimately governing the efficiency of the subsequent enzymatic hydrolysis. Dilute acid, hot water, steam explosion, and ammonia fiber expansion pretreatments are among the leading thermochemical pretreatments with a limited delignification that can reduce biomass recalcitrance. Practical applications of these pretreatment are rapidly developing as illustrated by recent commercial scale cellulosic ethanol plants. While these thermochemical pretreatments generally lead to only a limited delignification and no significant change of lignin content in the pretreated biomass, the lignin transformations that occur during these pretreatments and the roles they play in recalcitrance reduction are important research aspects. This review highlights recent advances in our understanding of lignin alterations during these limited delignification thermochemical pretreatments, with emphasis on lignin chemical structures, molecular weights, and redistributions in the pretreated biomass.


Lignin Thermochemical pretreatment Limited delignification Structural alterations Recalcitrance 



This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The work was supported and performed as part of the BioEnergy Science Center (BESC). The BioEnergy Science Center is a U.S. Department of Energy Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Yunqiao Pu
    • 1
    • 5
  • Fan Hu
    • 2
    • 5
  • Fang Huang
    • 2
  • Arthur J. Ragauskas
    • 1
    • 3
    • 4
    • 5
  1. 1.Biosciences DivisionOak Ridge National LaboratoryOak RidgeUSA
  2. 2.School of Chemistry and BiochemistryGeorgia Institute of TechnologyAtlantaUSA
  3. 3.Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleUSA
  4. 4.Department of Forestry, Wildlife, and Fisheries, Center for Renewable CarbonUniversity of TennesseeKnoxvilleUSA
  5. 5.BioEnergy Science CenterOak RidgeUSA

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