A Food Protein-Based CO2/N2-Responsive Magnetic Platform for Accelerated Pickering Interfacial Biocatalysis in Flavor Ester Synthesis

Abstract The enzymatic synthesis of flavor esters is often limited by poor interfacial mass transfer and water-induced equilibrium constraints in conventional systems. Herein, we report a food-grade magnetic Pickering interfacial biocatalysis (PIB) platform based on sodium caseinate (NaCas)–Fe2O3 nanoparticles for accelerated flavor ester synthesis. The nanoparticles, synthesized via a one-pot coprecipitation method, exhibit excellent colloidal stability, CO2/N2-responsive behavior, and magnetic responsiveness. Under an external magnetic field, magnetic actuation induces localized interfacial perturbations that promote substrate exchange at the oil–water interface. Using CALB-catalyzed synthesis of hexyl hexanoate as a model reaction, the magnetically perturbed PIB system achieved over 2-fold higher catalytic efficiency than a static Pickering emulsion within 10 min. Furthermore, CO2/N2 responsiveness enables rapid demulsification and efficient recycling of both nanoparticles and enzymes, with yields exceeding 89% over five consecutive cycles. This work provides a protein-based, magnetically induced interfacial perturbation platform for clean-label flavor ester production.