EmulsionsEmulsions

Noadswood Science, 2011Noadswood Science, 2011

Emulsions To know what emulsions are and how they are useful

Tuesday, April 18, 2023

Word-search Complete the organic chemistry

word-search

Word-searchAcross: -

3. Distillation7. Alkane8. Polymerise9. Saturated

Down: -

1. Alkene2. Homologous4. Cracking5. Fractions6. Bromine

Processed Foods Processed foods, including vegetable oils, may have

chemicals added to them

Lecithin (E322) is one example – it is an emulsifier which allows oil and water to mix, used in margarine, ice cream, salad cream etc…

Additives are listed on the ingredients label of such foods, and many of these additives have E numbers to identify them…

Immiscible Liquids Immiscible liquids do not mix together, e.g. oil floats on

the surface of the water when mixed.

If you shake oil and water together then leave them to stand, tiny droplets of oil float upwards – they join together until eventually the oil is floating on the water again

This is not a useful property when concerned with foods which often contain both oil and water (such as salad cream) – without a binder to hold the two together they would keep separating…

Emulsifier Emulsifiers are molecules that have two different ends:

A hydrophilic end (water-loving) that forms chemical bonds with water but not with oils

A hydrophobic end (water-hating) that forms chemical bonds with oils but not with water

Emulsifier The hydrophilic 'head' dissolves in the water and the

hydrophobic 'tail' dissolves in the oil

In this way, the water and oil droplets become unable to separate out – the mixture formed is called an emulsion

Emulsifier Versus Emulsion

An emulsion is a mixture of oil and water

An emulsifier is a specific molecule able to bind the two ends so they ‘stick together’ (i.e. the oil and water bind)

E.g. Lecithin is an emulsifier which binds the emulsion of water and oil

Emulsifier Experiment Carry out the emulsifier experiment to identify which

emulsifier is best at making an emulsion between oil and water…

Consider how stable the different emulsifiers are, what differing properties they possess and which one you would choose to use

Design your own table for results, variables to control and measure and then proceed to experiment

Note your findings coming to the ‘best emulsifier’ conclusion (and how you came to this)

Emulsions There are many common emulsions, including: -

Butter

Milk

Ice cream

Mayonnaise

Moisturising lotion

Emulsion paint

Egg yolk

Salad cream

Margarine

Skin cream

Properties Emulsions are thicker than oil or water and have many

uses that depend on their special properties

Emulsions can provide better texture or coating ability and appearance