Structural features and antioxidant activity of xylooligosaccharides enzymatically produced from sugarcane bagasse

Xylooligosaccharides (XOS) were prepared from xylan-rich hemicelluloses isolated by potassium hydroxide from sugarcane bagasse by hydrolysis with crude xylanase secreted by Pichia stipitis. Hydrolysis for 12 h produced XOS with a maximum yield of 31.8%, equivalent to 5.29 mg mL−1 in the hydrolyzate. XOS with degrees of polymerization (DP) from 2 to 4 (xylobiose, xylotriose, and xylotetraose) were the major components in the hydrolysates, whereas the oligosaccharides with higher DP of 5–6 (xylopentaose and xylohexose) showed a constant low level. FT-IR and NMR (1H, 13C, HSQC) demonstrated that XOS contained Araf and 4-O-Me-α-d-GlcpA residues. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay showed that the XOS exhibited concentration-dependent antioxidant activity. The results obtained indicate that the XOS produced from sugarcane bagasse can be employed in food-related applications.