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Pickering Emulsions

Identification

Key words nano-particles, emulsion, stability, charge, polarity, interface, shelf life, texture; particle-stabilized
Latest version 2012/07/17
Completed by DIL

How does it work?

Primary objective The tool combines stabilization and structure formation processes with the aim of formation of pH-stable emulsions with special rheological properties
Working principle Formation of Pickering emulsions is possible by conventional emulsifying techniques. Instead of the usual emulsifiers, nano-scaled particles with specific surface properties (ratio of polar and dispersive parts of surface energy) are applied for interface stabilization; physico-chemical interactions. Particulate material accumulates at oil–water and air–water interfaces in food systems and contributes the stabilization of emulsions and foams. This particle layer prevents droplet flocculation and coalescence by a steric mechanism and the phenomenom was named after S.U. Pickering in 1907.
Images
Additional effects Pickering emulsions are much more stable against ambient changes (pH-value, ions, temperature) than conventional emulsions; completely different rheological and textural properties may be achieved; Emulsifier content can be reduced
Important process parameters homogenisation conditions
Important product parameters charge, polarity distribution of nano-particles surfaces, size distribution of particles, wettability, concentration

What can it be used for?

Products Oil-in-water emulsions (o/w), Water-in-oil emulsions (w/o)

Examples:

  • homogenized and reconstituted milks (O/W emulsions stabilized by casein micelles)
  • margarines and fatty spreads (W/O emulsions stabilized by triglyceride crystals)
  • whipped dairy cream and dessert toppings stabilized by partially aggregated emulsion droplets
Operations Emulsification
Solutions for short comings The tool answers potential industrial needs like “production of emulsion systems with high stability against pH-changes and considerably different rheological and texture properties from classical emulsions”

What can it NOT be used for?

Products Organic food products containing no additives (E-numbers)
Operations High pressure homogenisation (risk of abrasion)
Other limitations Substances for formation of Pickering interfaces have to be food grade (e.g.:agar, agarose, gellan and pectin)
Risks or hazards Not known

Implementation

Maturity Formation of Pickering emulsions is state of the art in certain centres of excellence. Scaling up to industrial scale is complicated and needs further development especially with respect to problems like abrasion and time necessary to cover interfaces. Lab-scale procedures can not meet the requirements of industrial production.
Modularity /Implementation Technique of stabilization of interfaces by nano-particles can be integrated in a wide range of emulsion production processes
Consumer aspects Food grade materials will have no problems with respect to consumer acceptance. Use of additives (E-numbers) may be more critical consumer acceptance problems may occur with respect to harmlessness of nano-particles
Legal aspects Substances used for formation of Pickering interfaces have to be permitted
Environmental aspects No information, no problems expected

Further Information

Institutes University of Leeds
Companies Wacker, AQUANOVA AG
References 1. Gottschalk-Gaudig,Torsten et al., Wacker-Chemie GmbH, Germany, Emulsifier-free particle-stabilized emulsions. Patent WO2005092989, Mar 25, 2005.

2. Schmitt, V. et al.: Pickering emulsions. Cahiers de Formulation 2005, 12, 17-30.

3. Hedges, Nicolas David, Conopco Inc. DBA Unilever, Particle stabilised emulsion composition. Patent US2009087464 (A1), April 02, 2009.

4. Lagaly, G.; Reese, M.; Abend, S.: Smectites as colloidal stabilizers of emulsions: II. Rheological properties of smectite-laden emulsions. Applied Clay Science 1999, 14 (5-6), 279-298.

5. Binks, B. P. et al.: Naturally Occurring Spore Particles at Planar Fluid Interfaces and in Emulsions. Langmuir 2005, 21 (18). 8161-8167.

6. Dickinson, Eric: Food emulsions and foams: Stabilization by particles. Current Opinion in Colloid & Interface Science 2010, 15 (1-2), 40-49.

7. Dickinson, E., Interfacial particles in food emulsions and foams. In: B.P. Binks and T.S. Horozov, Editors, Colloidal particles at liquid interfaces, Cambridge University Press, Cambridge, UK (2006), pp. 298–327

8. Ramsden, W, Separation of solids in the surface-layers of solutions and ‘suspensions’ (observations on surface-membranes, bubbles, emulsions, and mechanical coagulation)—preliminary account, Proc. R. Soc. 72 (1903), pp. 156–164

9. Pickering, S. U. (1907). J. Chem. Soc. Trans. 91 , 2001-2021



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Created by Ollewa on 2 March 2011, at 23:06