Properties of Water-Soluble Xylan from Different Agricultural By-Products and their Production of Xylooligosaccharides

Xylooligosaccharides (XOS) are non-digestible oligosaccharides with a significant role as functional food ingredients in the food industry. The present research is undertaken to evaluate water soluble xylan (WSX) extraction from eight different sources using water at ambient temperature (25 ± 2 °C) and structural characterization (FTIR, NMR, XRD, and TGA). Enzymatic production of XOS from extracted substrates and its characterization using HPLC-RID and FTIR is determined. WSX from orange fleshed sweet potato peel shows highest yield (9%), while the least (2.48%) is from Teff seed coat. FTIR structural identification of xylan confirms the presence of β-glycosidic linkages and acetyl groups; whereas ¹H NMR validates the occurrence of β-D-1,4-xylopyranose backbone with α-L-arabinofuranose and 4-O-methylglucuronic acid substituents. XRD and TGA characteristics of the extracts indicate similarities in the eight sources in comparison with standard beech wood xylan. WSX is hydrolyzed with endoxylanase to obtain XOS (highest yield of 57.16 ± 1.01% in Cassava cake; lowest yield of 21.72 ± 0.72% in Bambara groundnut). HPLC-RID reveals xylobiose as the main monomeric sugar component (DP 2) and β-linkages are identified by FTIR in all the sources. The study suggests the potential commercial production of XOS from the analyzed agricultural by-products.