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Vegetable Oils - Emulsifiers.

What is an Emulsifier?

An emulsifier can make an emulsion more stable by
making the oil droplets stay in the water for a longer time.

Examples of food emulsifiers are mustard and
egg yolk (the yellow bit in the middle).

Mayonnaise is an emulsion of oil and water
using egg yolk as an emulsifier.
Mayonnaise also contains lemon juice or vinegar.

How does an Emulsifier work?

An emulsifier molecule works by having two parts.
One part of the molecule has an electric charge
(like an ion) and will dissolve in water but not in oil.
This part of the molecule (known as the head) is
called hydrophilic which means water loving.
The other part (called the tail) is a long hydrocarbon
which will dissolve in oil but not in water. This
part of the molecule is called hydrophobic which means
water fearing. The picture below shows the hydrophilic
head and the hydrophobic tail of an emulsifier molecule.

Emulsifier showing Hydrophobic Head and Hydrophilic Tail

The emulsifier molecule dissolves with its head in
the water and its tail in the oil droplet. A large number
of emulsifier molecules are needed to keep the
oil droplet dispersed in the water for a long time.

The picture above shows how the emulsifier molecules
position themselves to make an oil droplet more stable.

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