n this study, the effect of torrefaction on the chemical and structural transformation of lignocellulosic
biomass was investigated using complementary analytical tools. It was observed that the acid-insoluble
fraction was increased from approximately 30 to 38% and the methoxyl content was decreased to about
half after torrefaction at 330 ◦C for 2.5 min. These results highlight the formation of condensed structures
along with lignin transformation via demethoxylation. Solid-state NMR spectroscopy indicated that upon
torrefaction the aromaticity increased from about 36 to 60%. For the sample torrefied at 330 ◦C, the nonprotonated
aromatic carbon fraction was found to be about 60% of total aromatic carbons, indicating
the formation of large aromatic clusters. The complementary analyses used in this study are proposed
as a suitable approach for the elucidation of chemical and structural transformation of biomass during
thermal treatment.