Encapsulation and release of citral using nanostructured lipid carriers: A study on the impact of different preparation methods

The current study compared the effects of three different preparation methods (dispersion, ultrasonication and microfluidization) on the encapsulation of citral in nanostructured lipid carrier (NLC). The effects of surfactant, citral addition amount and solid-to-liquid lipid mass ratio over the NLC characteristics were studied. The obtained citral loaded NLC had a particle size of 192.8 ± 3.61 nm, a polydispersity index (PDI) of 0.243 ± 0.01, a Zeta potential of −34.2 ± 0.34 mV, an entrapment efficiency (EE%) of 78.37% ± 3.76%, and a loading efficiency (LE%) of 26.19% ± 1.26%. The physicochemical stability of citral was improved by encapsulation as shown in all NLC. In addition, the release kinetics revealed that the release of citral after 35 days storage was significantly lower from ultrasonication-NLC (almost no release at 4 °C, 61.09% at 25 °C) than that from microfluidization-NLC (9.63% at 4 °C, 72.56% at 25 °C). The energy input from the ultrasonication may result in stronger interaction forces within the particles. While the lipid structure of microfluidization-NLC was defective and easier to release citral. Therefore, ultrasonication was more suitable for the preparation of citral loaded NLC. The current study provides an essential reference for the process of preparing citral loaded NLC.