An emulsion consists of two immiscible liquids, like oil and water, with one dispersed as small spherical droplets in the other. There are two types of simple emulsions: water-in-oil and oil-in-water. Food emulsions are usually stabilized by emulsifiers and have droplet sizes ranging from 0.1 to 100 micrometers. The formation of emulsions requires the dispersion of one liquid phase into small droplets through processes like homogenization, which increases the interfacial area between the phases.

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FOOD EMULSIONS
Abd Karim Alias, 2013©
Prof. Abd Karim Alias
Universiti Sains Malaysia
Photo
courtesy
of
Tim
Sackton
on
Flickr

2. 2
} An emulsion consists of two
immiscible liquids (oil & water),
with one of the liquids dispersed
as small spherical droplets in the
other.
} In foods, the diameter of these
droplets usually falls somewhere
in the range 0.1 – 100 µm.
Food Emulsion
Abd Karim Alias, 2013©

3. 3
} Two types of simple emulsion:
} Water-in-oil (w/o): margarine,
butter, spreads
} Oil-in-water (o/w): mayonnaise,
salad dressings, milk, beverages,
cream, soups, sauces
} The dispersed and/or continuous
phase of many food emulsions may
be partly crystalline, rather than
being completely liquid.
Food Emulsion
Abd Karim Alias, 2013©

4. 4
} Emulsion formation requires the
dispersion of one phase into small
droplets ⇒ this results in a massive
increase in interfacial area between the
dispersed & continuous phase.
} Homogenization is the process by which
the dispersed phase is broken into small
droplets; high pressure homogenizers (10
– 100 MPa) are now very common.
Formation of Emulsion
Abd Karim Alias, 2013©

5. 5
Formation of Emulsion
Abd Karim Alias, 2013©

6. 6
Formation of Emulsion
Ì
Shear force
Abd Karim Alias, 2013©

7. 7
Importance of Large Interfacial Area
For a fixed composition:
• Decrease size, increase number of
particles
• Increase area of interfacial contact
Increase area
Abd Karim Alias, 2013©

8. 8
Formation of Emulsion
Abd Karim Alias, 2013©