Natural Selection - Get as PowerPoint by NBtooY5



            Noadswood Science, 2011
                                                   Sunday, September 30, 2012

   To know what emulsions are and how they are useful
   Complete the organic chemistry word-
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

   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…
   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
   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)
   There are many common emulsions, including: -
       Butter
       Milk
       Ice cream
       Mayonnaise
       Moisturising lotion
       Emulsion paint
       Egg yolk
       Salad cream
       Margarine
       Skin cream
   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

To top