Microemulsions are isotropic thermodynamically stable mixtures of two immiscible solvents stabilized by surfactants, with extensive applications in many areas such as: chemical reactions, nanoparticle preparation, foods industry and separation process in pharmaceutical industry. However, the application of microemulsions (MEs) in foods is limited by the types of tensoactives used in the formation of microemulsion. Many surfactants are not allowed in foods industry, while others can be added only in low quantities. Furthermore, the alternatives of food grade surfactants adequate to the formation of water in oil (W/O) MEs are limited. The aim of this work is the evaluation of different food grade surfactants (lecithin, Polyglycerol polyricinoleate (PGPR) and sorbitan monooleate (Span 80)) on the formation of W/O MEs and their application in the microencapsulation of betalain extract by complex coacervation. To achieve the objective, ternary and pseudoternary phase diagrams will be built of mixtures of water, soybean oil, surfactant and, if necessary, cosurfactant. The formed W/O MEs isotropic phases will be priorized, whose properties will be investigated by dynamic light scattering, small angle x-ray scattering (SAXS), rheology and differential scanning calorimetry (DSC). After characterization of the formed W/O MEs, these will be evaluated as vehicles for the encapsulation of betalains, which are hydrophilic and will be confined in the aqueous microvolume in the MEs. We intend also to investigate the effect of addition of betalains on the structure and stability of the MEs. Finally, the MEs containing betalains will be used for the preparation of a secondary emulsion, which will be subjected to the process of microencapsulation by complex coacervation. The formed capsules will be characterized according to morphology, particle size distribution, color parameters and oxidative stability.
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