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Emulsions stabilised by whey protein microgel particles: Towards food-grade Pickering emulsions

Destribats, Mathieu; Rouvet, Martine; Gehin-Delval, Cécile; Schmitt, Christophe; Binks, Bernard P.

Authors

Mathieu Destribats

Martine Rouvet

Cécile Gehin-Delval

Christophe Schmitt



Abstract

We have investigated a new class of food-grade particles, whey protein microgels, as stabilisers of triglyceride-water emulsions. The sub-micron particles stabilized oil-in-water emulsions at all pH with and without salt. All emulsions creamed but exhibited exceptional resistance to coalescence. Clear correlations exist between the properties of the microgels in aqueous dispersion and the resulting emulsion characteristics. For conditions in which the particles were uncharged, fluid emulsions with relatively large drops were stabilised, whereas emulsions stabilized by charged particles contained smaller flocculated drops. A combination of optical microscopy of the drops and spectrophotometry of the resolved aqueous phase allowed us to estimate the interfacial adsorption densities of the particles using the phenomenon of limited coalescence. We deduce two classes of particle arrangement. Complete adsorption of the particles was obtained when they were neutral or when their charges were screened by salt resulting in at least one particle monolayer at the interface. By contrast, only around 50% of the particles adsorbed when they were charged with emulsion drops being covered by less than half a monolayer. These findings were supported by direct visualization of drop interfaces using cryo-scanning electron microscopy. Uncharged particles were highly aggregated and formed a continuous 2-D network at the interface. Otherwise particles organized as individual aggregates separated by particle-free regions. In this case, we suggest that some particles spread at the interface leading to the formation of a continuous protein membrane. Charged particles displayed the ability to bridge opposing interfaces of neighbouring drops to form dense particle disks protecting drops against coalescence; this is the main reason for the flocculation and stability of emulsions containing sparsely covered drops. © 2014 the Partner Organisations.

Journal Article Type Article
Publication Date Sep 28, 2014
Journal Soft matter
Print ISSN 1744-683X
Electronic ISSN 1744-6848
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 10
Issue 36
Pages 6941-6954
APA6 Citation Destribats, M., Rouvet, M., Gehin-Delval, C., Schmitt, C., & Binks, B. P. (2014). Emulsions stabilised by whey protein microgel particles: Towards food-grade Pickering emulsions. Soft matter, 10(36), 6941-6954. https://doi.org/10.1039/c4sm00179f
DOI https://doi.org/10.1039/c4sm00179f
Keywords Pickering emulsions, Microgel, Whey protein, Limited coalescence
Publisher URL http://pubs.rsc.org/en/content/articlehtml/2014/sm/c4sm00179f
Copyright Statement ©2016 University of Hull
Additional Information This is the author's accepted manuscript of an article published in: Soft matter, 2014, v.10.

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