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Module 1: Aditivos alimentarios

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XSIQ
*

Chemistry - Emulsifiers

Emulsifiers

Emulsifiers [1] are chemical substances added to food to produce or
maintain consistency or smooth texture. Emulsifiers establish a chemical
bridge between polar (water-soluble) and non-polar (oil-soluble) components
of a food.

Substances containing emulsifiers are described as emulsions. To produce
an emulsion, it is necessary to stabilise the suspension of small droplets
of one liquid in another. The emulsifier establishes a chemical bridge
between the suspended droplets and the bulk liquid.

Emulsions may be oil-in-water (O/W) or water in oil (W/O) depending on the
dispersed medium. The general structures of (O/W) and (W/O) emulsions are
shown below:

The hydrocarbon tails of the emulsifier molecules become buried in the oil
droplets, as both are non-polar. The polar heads of the emulsifier
molecules have the effect of making the surface of the oil polar and so
attracted to the water. Common (O/W) emulsions include homogenised milk and
mayonnaise.

The polar heads of the emulsifier molecules will be buried in the polar
water droplets. The non polar tails of the emulsifier molecules effectively
make the surface of the water droplets non-polar and so attracted to the
oil. Common (W/O) emulsions include butter and margarine.

Common emulsifiers include:

(food additive 471).

and

Lecithin is present in common foodstuffs such as mayonnaise and icecream.
In mayonnaise it enables the oil droplets to remain suspended in water
(vinegar). If lecithin were not used in icecream it would form ice crystals
and lose its smooth texture.

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