Multiscale investigation of bamboo parenchyma cell walls as an easily decomposable biomass

A cell wall with a weaker structure and fragile biomass recalcitrance will enhance the chemical conversion efficiency of biomass energy and decrease consumption. In this work, the weak cell wall structure of bamboo parenchyma cells has been comprehensively and systematically analyzed at both anatomical and chemical levels, through investigations of cell wall porosity, moisture absorption characteristics, chemical composition content, and their distribution patterns within the cell wall. The results indicated that parenchyma cells exhibit a loose, multi-layered structure comprising thin and thick layers, along with a lower cell wall density attributed to their increased porosity volume. Dynamic water vapor sorption (DVS) results demonstrate that parenchyma cells possess higher equilibrium moisture content (EMC) and a more pronounced hygroscopic hysteresis effect across various humidity levels. Upon hemicelluloses removal, the enhancement of moisture absorption hysteresis suggests a spatial arrangement influence of polymers within the cell wall. Regarding chemical composition distribution, principal component analysis (PCA) successfully delineated the boundary effect inherent to Imaging FTIR resolution limitations, revealing the hemicellulose-rich distribution pattern in parenchyma cells, consistent with wet chemistry findings. Furthermore, Imaging Raman unveiled, for the first time, the uneven distribution of polysaccharides within the thin and thick layers of parenchyma cells, with uniform lignin distribution. This comprehensive analysis of the structural characteristics of parenchyma cells provides insights into their suitability as easily decomposable raw materials for biomass conversion.