The shoulder at 1731 crrr1 in the spectrum of the bran corre¬sponded to vibrations of the acetyl and uronic ester groups of hemicelluloses or to the ester linkage of carboxylic group of the ferulic and p-coumaric acids of lignin (Cherian et al., 2008). This peak did not appear in the spectrum of the CT-treated nanofiber, because the bleaching process removed most of the hemicelluloses and lignin from the CNFs. Siqueira, Bras, and Dufresne (2010b) attributed bands near 1730 crrr1 to deformation of the c=0 groups of xylan, the main component of hemicelluloses. The absence of this band in the spectrum of the ET-treated nanofibers confirmed that xylanase acted on the sample during ET.