A brief description of how emulsifier works, i.e., via its surface active property.

1. Abd Karim Alias, 2013
EMULSIFIERS!
Prof. Abd Karim Alias
Universiti Sains Malaysia
Photo
courtesy
of
B,
K,
&
G
on
Flickr

2. 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.

3. 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

4. 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.

5. 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

6. Abd Karim Alias, 2013©
How
does
emulsifier
work?
(-­‐-­‐-­‐cont’)
Without emulsifier
With emulsifier

7. Abd Karim Alias, 2013©
EMULSIFIERS!
Structure of emulsifier molecule

8. Abd Karim Alias, 2013©
EMULSIFIERS!
W/O emulsion O/W emulsion

9. Abd Karim Alias, 2013©
EMULSIFIERS!
Immobilization of water by
hydrophilic chain at the oil-water
interface
Stabilization of emulsion via
simple steric hindrance