Xylo‐Oligosaccharide (XOS) Formation through Hydrothermolysis of Xylan Derived from Viscose Process

Abstract

Abstract Xylo‐oligosaccharides (XOS) have gained growing interest during the past decade owing to their beneficial influence on health. At the same time, a trend to a more effective utilization of biomass and biomass degradation products can be observed. As a consequence, also the steeping‐lye of the viscose process is discussed as a potential source of new products based on xylans, xylooligosaccharides, xylose, and different xylose degradation products, thus being a driving force for the development of appropriate production processes. Therefore, xylan isolated from the steeping‐lye was subjected to hydrothermal degradation for production of xylo‐oligosaccharides (XOS). The experiments were carried out at 120, 150, and 180 °C, respectively. This hydrothermal treatment led to a soluble fraction, consisting of neutral and acidic XOS, and an insoluble residue predominantly made up of highly crystalline cellulose. A mass balance was established to calculate the activation energy for hydrothermal xylan degradation from weight loss kinetics. The degree of polymerization (DP) of the neutral product fraction could be influenced in a wide range by the reaction conditions applied. Acidic XOS were further characterized using mass spectrometry (MS). A 4‐ O ‐methylglucuronic acid residue α ‐(1,3)‐linked to the xylose backbone was detected as a new structural element in alkaline degradation products derived from beech wood xylan.