Formulation engineering of “Pickering Emulsions” – Novel functionalities and potential applications
Tom Mills & Fotios Spyropoulos, University of Birmingham
The fact that emulsions can be stabilised by finely divided solid particles was first reported over a century ago. The discovery of this type of emulsions is usually ascribed to Pickering (hence the term “Pickering emulsions”) who published the first extensive experimental study on particle-stabilised emulsions for plant sprays applications. Despite their early discovery Pickering emulsions have only recently started to attract interest for applications in a wide range of science areas of industrial relevance. The current presentation will give an overview of the advantages and disadvantages currently associated with these systems in an effort to demonstrate the potential impact their use could impart to current formulations. In addition to this, an overview of recent formulation engineering approaches to construct and use Pickering-stabilised emulsion structures to design products with novel functionalities will be given.
The focus of this presentation will progressively shift to advances in relation to food formulations. The use of edible (“food-grade”) Pickering particles (e.g. polysaccharide-based particles, fat crystals) to formulate emulsions will be presented. Emphasis will be given to the effects of using Pickering particles on the emulsion microstructure as it is developed during processing (emulsification) and also on the resulting emulsion microstructure and stability post production. Emulsions that are stabilised by a mixture of both particles and emulsifiers will be also discussed. These mixed emulsifier systems were found to induce long-term emulsion stability against coalescence via a synergistic “two-part” mechanism in which both the emulsifier and colloidal particles components have specific functions. The concluding parts of the presentation will focus on how the gained understanding regarding microstructure development and stability can be used to design foods with novel or improved functionalities. Simple and more complex (double) emulsion structures purposely designed and build using Pickering particles in order to achieve specific functionalities will be presented. The interplay between the exact “structuring role” of the Pickering particles in these emulsions and the overall structure resulting functionality, will be discussed in more detail.