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A brief description of how emulsifier works, i.e., via its surface active property.
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Abd Karim Alias, 2013
EMULSIFIERS!
Prof. Abd Karim Alias
Universiti Sains Malaysia
Photo courtesy of B, K, & G on Flickr
Abd Karim Alias, 2013©
EMULSIFIERS!
} Emulsifiers are substances which reduce the surface tension at the interface of two normally immiscible phases, allowing them to mix and form an emulsion.
} Emulsifiers belong to the general class of compounds called surface-active agents or surfactants.
Abd Karim Alias, 2013©
EMULSIFIERS!
Functions of Emulsifiers
} To promote emulsion stability, stabilize aerated systems, and control agglomeration of fat globules;
} To modify texture, shelf life, and rheological properties by complexing with starch and protein components;
} To improve the texture of fat-based foods by controlling the polymorphism of fats
Abd Karim Alias, 2013©
EMULSIFIERS!
How does emulsifier work?
} Emulsifiers reduce surface tension between the two immiscible phases due to their molecular structure. They have both a polar group with an affinity for water (hydrophilic), and a nonpolar group with an affinity for oil (lipohilic).
Ì Lipophilic tails are composed of C16 (palmitic) or longer fatty acids.
Ì Polar head groups may consists of anionic, cationic, amphoteric, or nonionic functional groups.
Abd Karim Alias, 2013©
How does emulsifier work? (-‐-‐-‐cont’)
} The presence of both regions on the emulsifier molecule allows them to orient themselves at the phase interface & lower the interfacial energy that leads to instability.
} Emulsifiers stabilize emulsions by means of monomolecular interfacial films & also by formation of steric and/or electrical barriers that prevent coalescence of the dispersed droplets.
Without emulsifier
With emulsifier
Abd Karim Alias, 2013©
How does emulsifier work? (-‐-‐-‐cont’)
Without emulsifier
With emulsifier
Abd Karim Alias, 2013©
EMULSIFIERS!
Structure of emulsifier molecule
Abd Karim Alias, 2013©
EMULSIFIERS!
W/O emulsion O/W emulsion
Abd Karim Alias, 2013©
EMULSIFIERS!
Immobilization of water by hydrophilic chain at the oil-water
interface
Stabilization of emulsion via simple steric hindrance
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