Determination of Lycopene Microemulsion Nanostructure Using Electrical Conductivity and Rheological Measurements

Microemulsions are optically transparent and thermodynamically stable systems showing selective and safe extraction capability of nutraceuticals from different plant matrices. Moreover, investigation of their nanostructure (normal micelle, reverse micelle, bicontinuous) provides noteworthy information with regard to application purposes. Therefore, in the present study the extraction of lycopene from the industrial waste of tomato paste plants was done using microemulsion technique (prepared with natural surfactant of saponin and cosurfactant of propylene glycol), and the divergent nanostructures of the single phase microemulsion were investigated by electrical conductivity and rheological measurements. These measurements along dilution lines in the pseudo-ternary phase diagram and water titration method showed good ability in simple and fast determination of different nanostructures and their boundaries in microemulsion region. Moreover, Herschel–Bulkley model fitted best with upward mode (shear rate–shear stress) of all tested samples.