Study of the Pickering emulsion stabilizing ability of deep eutectic solvent-ultra high pressure homogenization...

Nanocelluloses are versatile, bio-based materials capable of forming stable colloidal systems via Pickering stabilization. The combination of deep eutectic solvent (DES) pretreatment with ultra-high-pressure homogenization (UHPH) represents a promising green strategy to produce functional nanocellulose particles with tunable properties. In the present work, choline chloride-based DESs with glycerol (Ch_G), urea (Ch_U), or malic acid (Ch_MA) were used to pretreat microcrystalline cellulose prior to UHPH processing, yielding nanocelluloses with distinct morphologies and surface characteristics. Pickering oil-in-water emulsions were prepared, and their microstructure, rheological behavior, and colloidal stability were evaluated under varying temperature, pH, and ionic strength conditions. Ch_G and Ch_U treated nanocellulose exhibited long, flexible fibrils that stabilized the o/w emulsions primarily through network-mediated steric hindrance and lipid droplet immobilization. In contrast, Ch_MA treated nanocellulose featured shorter, highly charged particles that enhanced droplet dispersion via electrostatic repulsion though showing higher sensitivity to pH and ionic strength. Overall, the Pickering o/w emulsions demonstrated high stability over a broad range of temperatures (25-50 °C), pH values (4.5-10), and ionic strengths (≤ 200 mM NaCl), highlighting the effectiveness of DES-UHPH processing for tuning nanocellulose-based Pickering stabilization mechanisms in food-relevant emulsion systems.