Construction of an enzyme-Pickering emulsion catalytic system and its application in the interfacial catalytic reaction of rice bran oil deacidification

Solid particles play very important roles in stabilizing Pickering emulsions and improving interfacial catalytic reactions. In this study, hydrophobic modified Fe3O4@SiO2 particles were constructed and used to deacidify rice bran oil (RBO) in enzyme-Pickering emulsions as emulsifiers in the presence of lipase. The results showed that the particles had a core-shell structure with a zeta potential of −24.2 mV, an average particle size of 282.4 ± 1.30 nm, a contact angle of 83.8°, and a rough surface. Optimal Pickering emulsion stability was achieved by an Fe3O4@SiO2 particle concentration of 1.0 g/100 mL, oil/water ratio of 4:6, homogenization speed of 20,000 rpm and temperature of 50 °C. The saturation magnetization value of the emulsifier decreased from 28 emu/g to 5.8 emu/g after 15 reuses. Fluorescence microscopy results revealed that lipase was adsorbed at the oil-water interface when 10 mL/100 mL lipase was added to the continuous phase, which indicated the formation of an enzyme-Pickering emulsion. The enzyme-Pickering emulsion catalytic system was distinguished by a short reaction time (6 h) and good reusability of lipase after 12 reuses (relative activity of 72%) in the deacidification process of RBO. These findings provide a theoretical basis for enzyme-Pickering emulsion application in a magnetic fluidized bed.