Enhanced freeze-thawing stability of water-in-oil Pickering emulsions stabilized by ethylcellulose nanoparticles and oleogels

This study developed water-in-oil (W/O) Pickering emulsions stabilized by ethylcellulose (EC) nanoparticles and EC oleogels, which presented significantly improved freeze-thawing (F/T) stability. Microstructural observation suggested EC nanoparticles were distributed at the interface and within the water droplets, and the EC oleogel trapped oil in the continuous phase. Freezing and melting temperatures of water in the emulsions with more EC nanoparticles were lowered and the corresponding enthalpy values were reduced. F/T led to lower water binding capacity but higher oil binding capacity of the emulsions, compared to the initial emulsions. Low field-nuclear magnetic resonance confirmed the increased mobility of water but decreased mobility of oil in the emulsions after F/T. Both linear and nonlinear rheological properties proved that emulsions exhibited higher strength and higher viscosity after F/T. The widened area of the elastic and viscous Lissajous plots with more nanoparticles suggested the viscosity and elasticity of emulsions were increased.

Automated summary

This study developed water-in-oil Pickering emulsions stabilized by ethylcellulose nanoparticles and EC oleogels, which showed improved freeze-thaw stability. Microstructural observation revealed the distribution of EC nanoparticles at the interface and within the water droplets, while the EC oleogel trapped oil in the continuous phase. Freezing and melting temperatures were lowered and enthalpy values reduced with more EC nanoparticles. Freeze-thawing led to decreased water binding capacity but increased oil binding capacity. NMR confirmed increased water mobility but decreased oil mobility after freeze-thawing. Rheological properties showed higher strength and viscosity after freeze-thawing. The widened area of Lissajous plots with more nanoparticles indicated increased viscosity and elasticity of the emulsions.