Emulsions Noadswood Science, 2011

Emulsions  To know what emulsions are and how they are useful Friday, May 15, 2015

Word-search  Complete the organic chemistry word- search

Word-search Across: - 3. Distillation 7. Alkane 8. Polymerise 9. Saturated Down: - 1. Alkene 2. Homologous 4. Cracking 5. Fractions 6. 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