Emulsifier free emulsion: Comparative study between a new high frequency ultrasound process and standard emulsification processes

Emulsifier-free-emulsions were prepared with high frequency ultrasounds (HFU) generated by a piezoelectric ceramic transducer vibrating at 1.7 MHz. HFU emulsions were compared with emulsions made with standard emulsification processes: low frequency ultrasounds (LFU) and high pressure homogenization (HPH). Emulsions were prepared by combining sunflower oil with an aqueous phase either in the presence or absence of essential oil emulsifier. Oil droplets size distribution was determined by static light diffraction and nanoparticles tracking analysis (NTA) for the characterization of micrometric and nanometric droplets fraction respectively. More than 90% (v/v) of emulsion droplets were nanometric for HFU emulsions and were stable against coalescence during 30 days at 37 °C unlike other processed emulsions (LFU or HPH). Oily phases of emulsions analyzed by FTIR showed that oil composition was not affected during processing and that orange essential oil decreased edible oil oxidation during storage time.