A study on the optimization of the process for encapsulating D-limonene essential oil nanoparticles with ethyl cellulose by response surface methodology and its physicochemical properties

Objective This study aims to optimize the embedding process of D-limonene essential oil to solve the problems in its practical application，such as poor water solubility，obvious pungent smell and insufficient stability，and to provide a theoretical basis for its comprehensive utilization and the development of antioxidant functional products. Method With ethyl cellulose（EC）as the wall material and D-limonene essential oil（DL）as the core material，the D-limonene essential oil was encapsulated in ethyl cellulose by the anti-solvent precipitation method to form D-limonene essential oil/ethyl cellulose nanoparticles（DENPs）.Through single-factor experiments，the initial influence of the mass ratio（core-wall material ratio），the liquid ratio（ratio of core-wall material and positive/negative solvents）and the dripping speed（the speed at which the core-wall material drips from the positive solvent to the negative solvent）on the encapsulation rate of nanoparticles were investigated.On this basis，a three-factor three-level response surface analysis experiment was conducted using the encapsulation rate as the response value to optimize the optimal preparation process conditions.The DENPs were characterized by scanning electron microscopy（SEM），particle size and zeta potential analyzer，Fourier transform infrared spectroscopy（FTIR），and differential scanning calorimetry（DSC），and their antioxidant capacity and stability were evaluated. Result （1）The optimal process parameters were obtained through response surface methodology：a mass ratio of 43：57，a solid-to-liquid ratio of 1.5%，and a dripping speed of 3 r/min，resulting in an entrapment efficiency of 69.02%.（2）The particle size of DENPs was 259.49 nm，the PDI was 0.194，and the Zeta potential was -38.05 mV.（3）FTIR spectra and DSC thermograms confirmed that D-limonene essential oil was successfully encapsulated in ethyl cellulose nanoparticles.（4）The DPPH radical scavenging rate of DENPs reached a maximum of 73.24%，and the ABTS radical scavenging rate reached a maximum of 71.08%.（5）The retention rate of DENPs was 73.37% after water bath at 100 ℃ and 75.49% after storage at 4 ℃ for 16 days. Conclusion The encapsulation effect of DENPs optimized by response surface methodology is remarkable.The particle size is uniform and it disperses well in water solution.The encapsulated D-limonene essential oil still exhibits excellent free radical scavenging ability； its stability has also been greatly improved.This research provides theoretical references and scientific basis for the wider application of D-limonene essential oil in functional foods and medicine fields.