Convenient fabrication of shellac-chitosan composite nanoparticles by antisolvent precipitation for efficiently...

Peppermint essential oil (PEO) is limited in its application due to high volatility and poor water solubility. In this study, a novel one-step antisolvent precipitation method was developed for the fabrication of shellac-chitosan composite nanoparticles (SH-CS NPs), in which a chitosan solution acted as the antisolvent, enabling simultaneous nanoparticle formation and complexation. The optimized nanoparticles (S5C5, SH:CS = 5:5) exhibited near-neutral wettability (contact angle ≈ 88.9°), facilitating the formation of stable Pickering emulsions for PEO encapsulation. At a particle concentration of 1.2 %, the emulsions achieved a high encapsulation efficiency of 84.15 % and demonstrated excellent physical stability, with no phase separation observed after 14 days. Moreover, the emulsion exhibited strong resilience to thermal (90 °C), ionic (400 mM NaCl), and centrifugal stresses. The enhanced stability was attributed to interfacial particle adsorption, three-dimensional network formation, and concentration-dependent bridging. This work offers a convenient and effective strategy for encapsulating volatile essential oils using biopolymer-based nanoparticles and provides valuable insights into the design of food-grade Pickering stabilizers.