Preparation and characterization of water in sesame oil microemulsion by spontaneous method

Microemulsions based on their formation mechanism comparing to kinetically stable nanoemulsions are thermodynamically stable. Moreover, water in oil microemulsions could be used for encapsulation of water soluble compounds or preparing low fat products. In this research, we investigated the effects of preparation and formulation conditions on the formation and physical properties of water in sesame oil microemulsions using spontaneous method. Results showed that PGPR comparing to Span 80 formed transparent nanoemulsion with 67 nm droplet size. To investigate PGPR ability for emulsifying higher amounts of dispersed phase, water content increased in fixed concentration of PGPR. Increasing water content (%WOR) from 10 to 50% increased droplet size and viscosity from 53 to 722 nm and from 115 to 183 mPa.s, respectively. By increasing stirring speed to 900 rpm, droplet size decreased to 45 nm, but increasing stirring time to 2.5 hr, droplet size increased to 72 nm comparing to standard conditions. Comparing to pure water dissolving Vitamin C in inner aqueous phase increased droplet size to 171 nm. Practical applications Water in oil microemulsions fabricated using spontaneous method due to their high stability could be used for preparing low fat products such as seasonings and sauces. In this study, internal aqueous phase increased as much as possible at a fixed concentration of surfactant and factors affecting the emulsion droplet size and consequently their stability were evaluated. Moreover, such emulsions could be used for encapsulating water soluble ingredients such as Vitamin C in aqueous phase.