Tailoring Nanostructured Cellulose for Efficient Pickering Emulsions Stabilization

Nanostructured celluloses, nanofibrils (CNFs) and nanocrystals (CNCs), are prepared through TEMPO-mediated oxidation by controlling the intensity of the process modulated by catalyst concentration and processing time. These nanomaterials are evaluated as stabilizers for Pickering emulsions, fabricated using high-pressure homogenization (HPH). Both CNFs and CNCs exhibit efficient steric and electrostatic stabilization of oil-in-water (O/W) emulsions. CNFs display strong inter-droplet interactions, leading to the formation of a 3D fibrous network emulsion with higher viscosity compared to CNCs-stabilized emulsions. However, CNFs also show a higher tendency towards flocculation, due to fibrils’ entanglement in the continuous phase. Interestingly, the HPH treatment has a notable impact on the nanofibrils’ interfacial layer, enhancing the emulsifying ability of CNFs and improving stability against coalescence. Conversely, CNCs-stabilized emulsions exhibit lower viscosity but demonstrate higher interfacial activity and stabilization capability. Remarkably, no phase separation during 10-months of refrigerated storage, indicating excellent long-term stability. Importantly, the HPH treatment does not significantly change the emulsifying ability of CNCs. In conclusion, this study highlights the possibility of obtaining nanocelluloses with tailored emulsifying properties by regulating the intensity of TEMPO-mediated oxidation applied to pulp cellulose. These findings open up new opportunities for the development of innovative ingredients for the food and cosmetic industries.