Protein-stabilized emulsions and nanoemulsions

This presentation will summarize briefly our current understanding of the scientific and technological basis for the formation of emulsions containing micrometer and nanometer sized droplets, with applications in food, cosmetic and pharma industries [1-3]. The focus will be on protein-stabilized emulsions. Their specific features will be summarized in comparison to the surfactant- and particle-stabilized emulsions [3]. The subtle relations between the material characteristics of the emulsions (oil type, emulsifier, pH, etc.) and the optimal hydrodynamic conditions for emulsification will be discussed [3] in the context of obtaining emulsions with desired properties. Examples of appropriate mixtures of proteins with other emulsifiers (lipids, lysolipids, natural gums) will be given. The differences between oil-in-water and water-in-oil emulsions will be briefly discussed [4,5]. Special focus will be given on the recent advance in production of nanoemulsions using high pressure homogenizers, high viscosity of the continuous phase, and/or high oil volume fraction during emulsification [6,7]. Some new methods for self-emulsification will be briefly reviewed [8,9]. The basic physicochemical and hydrodynamic concepts will be illustrated by multiple examples with real systems. References: David Julian McClements, Food Emulsions: Principles, Practices, and Techniques, 3rd Edition, CRC Press, 2015. Andreas Håkansson, Emulsion Formation by Homogenization: Current Understanding and Future Perspectives, Annu. Rev. Food Sci. Technol. 10 (2019) 239–258 (review article). S. Tcholakova, N. D. Denkov, and A. Lips, Comparison of Solid Particles, Globular Proteins and Surfactants as Emulsifiers. Phys. Chem. Chem. Phys. 10 (2008) 1608-1627 (review article). N. Politova, S. Tcholakova, N. D. Denkov, Factors Affecting the Stability of Water-oil-water Emulsion Films. Colloids Surfaces A 522 (2017) 608–620. N. Politova, S. Tcholakova, S. Tsibranska, N. D. Denkov, K. Muelheims, Coalescence Stability of Water-in-Oil drops: Effects of Drop Size and Surfactant Concentration. Colloids Surfaces A 531 (2017) 32–39. S. Tcholakova, I. Lesov, K. Golemanov, N. Denkov, S. Judat, R. Engel, T. Daner, Efficient Emulsification of Viscous Oils at High Drop Volume Fraction. Langmuir 27 (2011) 14783-14796. D. Gazolu-Rusanova, I. Lesov, S. Tcholakova, N. Denkov, B. Ahtchi, Food grade nanoemulsion preparation by rotor-stator homogenization. Food Hydrocolloids (2019) under review. S. Tcholakova, Z. Valkova, D. Cholakova, Z. Vinarov, I. Lesov, N. D. Denkov, K. Smoukov, Efficient Self-Emulsification via Cooling-Heating Cycles. Nature Comm. 8 (2017) 15012. Zh. Valkova, D. Cholakova, S. Tcholakova, N. Denkov, S. K. Smoukov, Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops. Langmuir 33 (2017) 12155−12170