Construction of electrostatic networks using bamboo-derived lignin nanoparticles and NaCl for stabilizing Pickering emulsions and enhanced curcumin retention.

Lignin nanoparticles (LNPs) have attracted increasing attention as sustainable Pickering stabilizers owing to their amphiphilic structure, biocompatibility, and intrinsic antioxidant activity. In this study, LNPs with antioxidant and UV-shielding properties were prepared from bamboo lignin via a p-toluenesulfonic acid/hydrogen peroxide (TPHP) pretreatment and subsequently applied to stabilize oil-in-water (O/W) Pickering emulsions. To regulate particle interactions, NaCl was introduced to adjust the ionic strength. At low salt concentrations, partial screening of electrostatic repulsion promoted reversible association among LNPs, leading to the formation of a weak electrostatic network that enhanced interfacial anchoring and interfacial layer compactness. Under the conditions of 1.0 wt% LNPs and 100 mM NaCl, the emulsion displayed small and uniform droplet sizes, pronounced viscoelastic behavior, and excellent storage stability exceeding 60 days. Using curcumin as a model bioactive compound, the LNPs/NaCl-stabilized system demonstrated high curcumin retention together with improved thermal stability (85.09% retention at 60 °C) and strong UV resistance (88.96% after 72 h). These results highlight the role of the LNPs-mediated electrostatic network in enhancing emulsion stability and protecting sensitive bioactive compounds. This work provides new insights into the design of sustainable lignin-based Pickering emulsions for stabilizing and protecting functional ingredients.