Emulsifiers
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Abd Karim Alias, 2013 EMULSIFIERS Prof. Abd Karim Alias Universiti Sains Malaysia Photo courtesy of B, K, & G on Flickr
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A brief description of how emulsifier works, i.e., via its surface active property.
Transcript of Emulsifiers
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
