Electrohydrodynamics for Efficient Droplet Coalescence in Food-Grade Non-Aqueous Pickering Emulsions

Coalescence is a fundamental process in emulsion synthesis. It can have positive effects depending on the approach. The emulsion stabilization can be reached when emulsifiers occupy all the droplet surface, and when low quantities of solid particles (Pickering emulsions) are used, stabilization can be reached under controlled arrested coalescence [1].<br/>The application of electro hydrodynamics on non-aqueous emulsion systems can produce emulsion droplets with controlled size distribution and coverage, and also induce coalescence. In the latter case, when an electric field is applied, dipolar emulsion droplets can be generated and short-range dipolar droplet-droplet interactions can take place. Positive surface charges on a droplet can attract negative charges on a neighboring droplet, eventually leading to so-called electro coalescence [2], [3].<br/>Here, we explore the electro-coalescence of food-grade droplets [4] of a non-aqueous system. Non-aqueous food-grade systems are scarcely investigated due to the miscibility of most edible oils, and the limitations of suitable polar protic solvents [5]. In this work, the electro-induced coalescence is shown for a non-aqueous Pickering emulsion with rapeseed or moringa oleifera oils as continuous phase, glycerol or lactic acid in ethanol as dispersed phase, and ethyl-cellulose or moringa oleifera leaf-based stabilizer particles.<br/>Our preliminary results provide insights into the application of electro hydrodynamics in the emulsification processing of food-grade Pickering systems.<br/><br/><b>Acknowledgements</b><br/>This work received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 956248.<br/><br/><b>REFERENCES</b><br/>[1] E. Durgut, C. Sherborne, A. Dikici, G. C. Reilly, and F. Claeyssens, “Preparation of Interconnected Pickering Polymerized High Internal Phase Emulsions by Arrested Coalescence,” <i>Langmuir</i>, vol. 38, pp. 10953–10962, 2022, doi: 10.1021/acs.langmuir.2c01243.<br/>[2] P. Dommersnes <i>et al.</i>, “Active structuring of colloidal armour on liquid drops,” <i>Nat. Commun.</i>, no. May, 2013, doi: 10.1038/ncomms3066.<br/>[3] Z. Rozynek, A. Mikkelsen, P. Dommersnes, and J. O. Fossum, “Electroformation of Janus and patchy capsules,” <i>Nat. Commun.</i>, no. May, pp. 1–6, 2014, doi: 10.1038/ncomms4945.<br/>[4] C. C. Berton-Carabin and K. Schroën, “Pickering emulsions for food applications: Background, trends, and challenges,” <i>Annu. Rev. Food Sci. Technol.</i>, vol. 6, pp. 263–297, 2015, doi: 10.1146/annurev-food-081114-110822.<br/>[5] A. Zia, E. Pentzer, S. Thickett, and K. Kempe, “Advances and Opportunities of Oil-in-Oil Emulsions,” <i>ACS Applied Materials and Interfaces</i>, vol. 12, no. 35. American Chemical Society, pp. 38845–38861, Sep. 02, 2020. doi: 10.1021/acsami.0c07993.