Hemicellulose from mild extraction of biomass: Revealing structural insights and advancing potential value

Hemicellulose is one of the main components of biomass, though often overlooked in technical applications. Its valorization depends on the properties of this natural carbohydrate polymer, which are defined by the type of biomass, and structural changes occurring during extraction processes. In this study, hemicellulose was extracted from various plant species using mild alkaline treatment, allowing to obtain polymers with close to their natural structure while differ from traditional descriptions of common commercially available xylans. Namely, lignin bonded to the carbohydrate and native degree of acetylation allows for amphiphilic properties of hemicelluloses. The surface activity and self-organization behaviour upon drying are though influenced mostly by the polymer molecular weight and branching. Hemicelluloses exhibit perforated lamellae structure at 10 min extraction times, whereas extraction exceeding 100 min results in hemicelluloses with lower surface activity. As extraction time increased, the molecular weight of hemicellulose decreased from 10⁴ to 10³ g/mol, accompanied by a reduction in the polydispersity index and a shift of the diffraction maximum to lower angles by 1.0° to 1.4°, indicating an increase in packing density. The consistency was supported by multidimensional characterization, demonstrating that isolating hemicellulose through mild extraction can modify its properties for applications in surfactants and adhesives.