Carboxylated chitin nanofibers as effective stabilizers in food-grade pickering emulsions

Pickering emulsions have significant potential in the food industry for their superior stability and environmental friendliness, but achieving long-term stability with natural stabilizers like chitin remains challenging. This study investigates the effects of carboxyl content in nano-chitin fibers (ChNFs) on emulsion stability. ChNFs with carboxyl content ranging from 580 to 1305 μmol/g were prepared via TEMPO oxidation, which disrupted the hydrogen bonds within chitin fibers, reduced crystallinity, and improved dispersibility. ChNF1000, with moderate carboxyl content, formed stable nanofiber networks, maintaining uniform droplet distribution and preventing aggregation. In contrast, unmodified chitin fibers (ChF) and ChNF580 showed poor stability due to insufficient electrostatic repulsion, while ChNF1305 exhibited structural relaxation caused by excessive surface charge, leading to instability. These findings demonstrate that optimizing the carboxyl content of ChNFs effectively improves Pickering emulsion stability, providing a strong basis for applications in food and biomedicine. Oxidation mechanism of nano-chitin and stabilization mechanism of Pickering emulsion. • Enhanced Emulsion Stability via TEMPO-Oxidized Nano-Chitin Fibers. • Precise Control of Carboxylation to Optimize Nano-Chitin Properties. • Synergistic Effects of Reduced Crystallinity and Tailored Fiber Length for Enhanced Pickering Emulsion Functionality. • Rheology-Driven Evaluation of Nano-Chitin as a Sustainable emulsifier. • Expanding Green Emulsification Strategies for Food-Grade Pickering Systems.