Emulsions and Emulsion Stability Analysis and Application in Chemical, Pharmaceutical and Food Industries

Dear Colleagues,

Emulsions consist of droplets of one liquid dispersed in another immiscible liquid. They are metastable dispersions; external shear energy is used to rupture large droplets into smaller ones during emulsification. Emulsions can be classified according to the distribution of the lipid and aqueous phases, for example, oil-in-water (O/W) and water-in-oil (W/O) emulsions. Multiple/double emulsions are also formulated, representing multicompartmentalized systems characterized by the coexistence of oil-in-water (O/W) and water-in-oil (W/O) emulsions, in which the globules of the dispersed phase contain smaller equally dispersed droplets within them. The most common are water-in-oil-in-water (W/O/W), although oil-in-water-in-oil (O/W/O) emulsions can also be used in specific applications. These colloidal dispersions are unstable and prone to changes in their properties with time. A few the most important physical mechanisms responsible for the instability of emulsions are gravitational separation (e.g., creaming and sedimentation), flocculation, coalescence, and phase inversion. Stability is the most important factor to be considered in emulsion technology; an emulsion is stable when there is no change in the size distribution or the spatial arrangement of droplets over the experimental time-scale.

Surfactants, or surface-active agents, have two main functions: providing colloidal stability to the droplet for a long time by forming an electrically charged layer at its interface with the continuous phase and lowering the interfacial tension, thereby making droplet formation less energy-intensive; and stabilization of the emulsion by restricting the mobility of the droplets of the disperse phase due to increases in the viscosity and sometimes viscoelasticity of the continuous phase. In many industrial processes, surfactants are added to improve the properties of the products. The rheology and emulsion stability are interrelated among them, and the emulsion rheology may not be understood without considering the structural parameters of the emulsion, such as the rheology of the continuous phase, the nature of particles, and inter-particle interactions.

Emulsions are of interest in many important practical applications in food, cosmetics, petroleum production, agriculture, chemical, oil and gas, pharmaceutical, and various other process industries.

This Special Issue on “Emulsions and Emulsion Stability Analysis and Application in Chemical, Pharmaceutical, and Food Industries” aims to select novel advances in the design, development, and application of emulsion technology.

Dr. Luis Alberto Garcia Zapateiro
Dr. Ronaldo Gonçalves dos Santos
Prof. Dr. Ana M. Forgiarini
Dr. Sina Rezaei Gomari
Guest Editors

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