Overview
ABSTRACT
This article provides an introduction to emulsions; it deals with the fundamental aspects of their formation and their stability as well as with their characterization and control at the industrial level. After having provided some definitions this article focuses on the physico-chemical aspects of these systems: drop rupture, droplets instability, role and selection of emulsifiers. The strategies of formulation, choice of components, manufacturing process and difficulties posed by scaling-up issues and phase inversion techniques are presented. Techniques and procedures for the characterization of emulsions are reviewed: visual inspection, microscopy, droplet size, rheology, long-term stability and the so called "accelerated aging" techniques. This article concludes on the case of less common emulsions such as transparent, concentrated, multiple or responsive emulsions.
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Pascal BROCHETTE: Doctorate from Université Paris VI, HDR, France - Atellane sarl, l'herbergement, France - Founder, trainer and consultant
INTRODUCTION
The term emulsion probably comes from the Latin "emulgere", meaning to milk. Today, the term designates a system comprising at least two immiscible liquids, one of which is dispersed in the other, in a more or less stable form. Strictly speaking, an emulsion is thermodynamically unstable. In practice, stabilities of up to several years can be observed. Stabilization of the system depends both on the energy expended in dispersing one liquid in the other, and on the know-how of the formulator, who is responsible for selecting the stabilizers.
The manufacture of emulsions has been known since antiquity, but their scientific study only dates back to the beginning of the 20th century . In the space of 100 years or so, the knowledge and use of emulsions in various applications has taken on an extraordinary scope. This article attempts to provide a concise description of both the physics of emulsions and a practical aspect of the development and study of these systems.
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KEYWORDS
cosmetic | food | pharmaceutical | formulation | emulsification
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Cosmetics: from design to product
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Bibliography
Directory
Manufacturers – Suppliers – Distributors (non-exhaustive list)
MALVERN INSTRUMENTS SA (zetametry, photon correlation granulometry [PCS] and laser diffraction [SLS], image analysis) http://www.malvern.co.uk
CORDOUAN TECHNOLOGIE (photon correlation particle sizing [PCS], zetametry, concentrated systems)
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