FTIR spectra of Native sugarcane bagasse (black online), Oxalic acid fiber expansion (OAFEX) (red online) and Enzyme digested cellulignin (blue online). 7b), 7c) and 7d) selected regions of Figure7a. The arrows indicate changes observed through the pretreatment. Hemicellulose and cellulose maxima appeared between frequency ranges of 1000–1200 cm–1 with maxima at 1037 cm–1due to C-O stretching. The absorption around 1463 cm–1 refers to CH2 and CH3 indicating the deformation of lignin while 1606 cm–1 is related to C=C stretching of the aromatic ring (lignin) and C=O stretching.