Search

According to the high interest in agro-industrial waste reutilisation, underutilised lignocellulosic materials, such as walnut shell (WS) and pea pod (PP), come in focus. The aim of this paper was to evaluate WS and PP as sources for the production of xylooligosaccharides (XOS). Hemicelluloses from WS and PP were recovered by combining varying parameters of delignification and alkaline extraction. At optimal recovery conditions, the fractions were further hydrolysed to XOS using GH11 endo-xylanase, by varying time and enzyme concentration. Xylose was predominant in the monomeric composition of the obtained hemicelluloses, building low-branched (arabino)glucuronoxylan, in WS exclusively, while in PP some xyloglucan as well. Delignification was essential for high recovery of total xylose from the materials, up to at least 70 %. High xylan conversions were obtained for 24 h hydrolysis, resulting in xylobiose and xylotriose when using low enzyme concentration, while in xylose and xylobiose with high enzyme concentration., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This work investigated the integration of a two-stage hydrothermal treatment for production of xylooligosaccharides (XOS), a high-value product, into the isolation process of cellulose nanofibrils (CNF) from sugarcane bagasse. Under optimized conditions, the first stage yielded a XOS-rich, high purity hydrolysate and in the second stage only a xylose-rich hydrolysate could be obtained at high purity. The resulting solid cellulosic fraction was delignified and bleached to obtain a cellulose-rich pulp, which was mechanically defibrillated by disc ultra-refining to CNF. Except for the viscosity, the sugarcane CNF showed properties (i.e., thermal stability, crystallinity and diameter size) comparable or superior to the CNF prepared from commercial bleached eucalyptus Kraft pulp. In conclusion, the integration of the two-stage hydrothermal treatment is an efficient and promising strategy to obtain hemicellulose-derived high-value co-products in the process of isolating CNF. In addition, lignin was also recovered as a co-product with yield comparable to other biomass fractionation approaches., (Copyright © 2020 Elsevier B.V. All rights reserved.)