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Title: Stability and characterisation of emulsions in the presence of colloidal particles and surfactants
Author: Pichot, Roman
ISNI:       0000 0004 2713 1852
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2012
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The stability against coalescence of vegetable oil-in-water “food grade” emulsions in the presence of both surfactant and colloidal particles (hydrophilic silica) has been studied and compared to the stability of systems where only the surfactant or the colloidal particles act as the emulsifier. No attempt was made to stop the emulsions from creaming. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants, monoolein and lecithin as the W/O surfactants. These mixed emulsifier systems were shown to induce long-term emulsion stability against coalescence, regardless of the surfactant type, via a synergistic “two-part” mechanism in which both the surfactant and colloidal particles components have specific functions. Nonetheless, the emulsion microstructure was proved to depend on the surfactant’s type and concentration: the use of O/W emulsifiers above a certain concentration induced a displacement of particles from the interface, while such a displacement was not observed using W/O emulsifiers. Further measurements of interfacial tension and contact angle showed that the level of adsorption of solid particles at the interface depended on the surfactant type and concentration.
Supervisor: Not available Sponsor: EPSRC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: T Technology (General) ; TP Chemical technology ; TS Manufactures