Fabrication of composite hydrogels by assembly of okara cellulose nanofibers and gum Arabic in ionic liquids: Structure and properties

Okara cellulose is an abundant natural polysaccharide with many potential industrial applications due to its structure-forming properties. In this study, we fabricated composite hydrogels from okara cellulose nanofibers (CNFs) and Arabic gum (AG) by dissolving these components in an ionic liquid ([Amim]Cl), heating them at 100 °C for 3 h, and then soaking them in a 1:1 water-isopropanol solution. The effects of AG concentration and sonication on the properties of the hydrogels was also examined. The structure and physicochemical properties of the okara CNF-AG hydrogels were studied, including their microstructure, physical state, surface properties, swelling, rheology, and thermal stability. Sonication promoted the formation of a hydrogen bonded network within the hydrogels, with low crystallinity and a porous structure. The mechanical properties of the composite hydrogels, such as their hardness, springiness, gumminess, and chewiness, could be optimized by controlling the sonication conditions and AG concentration. Indeed, these textural attributes were around 3–8-fold higher for the optimized sonicated hydrogels than for the non-sonicated ones. Sonication and AG concentration also altered the surface properties and thermostability of the hydrogels. The composite polysaccharide-based hydrogels developed in this study have potential applications as novel materials in food and non-food applications.