Unlocking one third of plant biomass as a renewable feedstock for fuels and materials depends on the effective deconstruction of the secondary plant cell wall. Over 90% of the native secondary plant
cell wall is composed of cellulose and hemicellulose polysaccharides and the lignin heteroaromatic
polymers. Deconstruction refers to the processes which digest polymers into desired subunits. Present
deconstruction processes are centered on lignin-first extraction to overcome the recalcitrance of
biomass: the accumulation of indigestible plant polymers during deconstruction. Recent availability
of 13C-enriched plant biomass has enabled the use of solid-state Nuclear Magnetic Resonance (NMR)
experiments to refine the model of native cell wall structure in plant tissue in biofuel relevant crops.
Solid-state NMR has the advantageous ability to non-invasively probe the structure of the secondary
plant cell wall throughout deconstruction pathways and potentially refine methods development for the
conversion of plant biomass to sustainable products. The mechanical preprocessing of plant material to
solubilize the plant cell wall could introduce recalcitrance at the beginning of the deconstruction
pathway. In this research solid-state NMR of Sorghum bicolor stems mechanically preprocessed on the
lab scale (by vibratory ballmilling at 30 Hz for 2 and 15 minutes) supported recalcitrant reorganization in
lignin and hemicellulose. Recalcitrance related to lignin becoming more rigid, potentially trapping other
polymers was supported by a reduction in highly dynamic signals of arabinosyl hemicellulose (correlated
in lignin-hemicellulose cross linkages), lignin linkages, and lignin probed in the refocused Incredible
Nuclear Enhancement by Polarization Transfer (rINEPT) experiment. Cross polarized experiments
targeting rigid polymers supported potential recalcitrance from structural hemicellulose as signals:
which persisted after milling at a greater signal intensity than cellulose. Recalcitrance from cellulose
polymers converting from crystalline to amorphous cellulose as fibril structures are broken down was
not supported here, the cellulose carbon 4 peaks was a valuable marker for identifying morphology
changes for the cellulose fibril along with scanning electron microscopy.