Preparation Of W/O/W Pickering Emulsion And Its Encapsulation For Bioactives

In this paper,hydrophilic and hydrophobic SiO₂ nanoparticles were used as Pickering emulsifiers,and then W/O/W Pickering emulsions were prepared by two different emulsification methods.Based on the sTab.Pickering emulsion,the hydrophilic actives EGCG and lipophilic actives V_E were separately encapsulated and co-encapsulated,which lay the foundation for the application of these kind of emulsions in cosmetics.First,W/O/W Pickering emulsions were prepared by one-step emulsification and two step emulsification separately.The structure of the emulsions was observed by microscope.The results showed that the two-step emulsification method was better than the one-step emulsification method.The effect of oil-water ratio and particle mass fraction on the storage stability of Pickering emulsions was investigated by single factor experiment.The results showed that when the ratio of oil to water was 6:4,the mass fraction of hydrophobic particles was 4%,the ratio of water to emulsion was 8:2,and the mass fraction of hydrophilic particles was 5%,the emulsions were the most sTab.of all.The influence of pH value and salt concentration on the stability of emulsions was studied.The results showed that the salt concentration had a negative effect on the stability of emulsion due to the electrostatic shielding effect of counterions.The emulsion was the most sTab.when pH was about 6 while pH value caused the change of particle surface potential,and when pH value was above or equal to 7.the creaming of emulsion happened,this indicated that the emulsion stability decreased.Secondly,different concentrations of hydrophilic actives EGCG and lipophilic actives V_E were encapsulated in sTab.W/O/W Pickering emulsion,respectively,and the effect of different concentrations of EGCG and V_E on the emulsions was studied.The results showed that the particle size and viscosity of emulsion increased with rasing the concentration of EGCG and V_E.High concentration of EGCG reduced the encapsulaion efficiency of emulsion,wheras high concentration of V_E had little effect on the encapsulation efficiency of emulsion.The relationship between storage stability of the actives encapsulated in the emulsion and storage conditions was explored.The results showed that the storage stability of the actives encapsulated in W/O/W Pickering emulsion was significatnatly impoved compared to that of EGCG aqueous solution and V_E oil solution.When V_E co-encapsulated with EGCG in emulsion,V_E could delay the degradation of EGCG to some extent.The addition of NaCl in the inner aqueous phase was beneficial to the encapsulation of hydrophilic actives.Finally,calcium alginate was used to encapsulate W/O/W Pickering emulsion containing EGCG and V_E together,which meant that the actives were encapsulated for the second time through the capsule system.It was found that the concentration of calcium chloride would affect the thickness of the capsules and the crosslinking degree.The concentration of sodium alginate?SA?would affect the formation of the capsules.The result of the release experiment showed that the W/O/W Pickering emulsion had good release ablitity after being encapsulated by calcium alginate,and the release rate could be adjusted by changing the concentration of CaCl₂ and SA.The addition of NaCl in outer phase would accelerate the release of actives,while the NaCl addition of inner phase could slow down the release of bioactives.