AQA Core Science C1 Part 2: Plant oils and their uses.

Vegetable oils have higher boiling points than water. As a result of this, foods then:

- cook faster
- have different flavours

Monounsaturated: one double bond in each fatty acid.

Polyunsaturated: more than one double bond in each fatty acid.

Saturated: only single bonds.

Unsaturated fats are said to be HEALTHIER than saturated fats.

Bromine water test:

Alkanes: stays the same (no reaction).
Alkenes: turns colourless (there is a reaction).

Saturated fats are solid at room temperature. They have a higher melting point than unsaturated oils.

Unsaturated oils can be 'hardened' by reacting them with hydrogen, a process called HYDROGENATION.

60 degrees celsius and a nickel catalyst are needed for hydrogenation.

                              :                                        :
H                  H ---- C ---- H                   H ---- C ---- H
 |        +                   |                                       |
H                           C ---- H                   H ---- C ---- H
                              ||                 -->                  |
                     H ---- C ---- H                  H ---- C ---- H
                               |                                       |
                     H ---- C ---- H                  H ---- C ---- H
                               :                                       :

There are two types of emulsions:

Oil droplets in water (eg. milk, ice-cream, salad, mayonnaise).

Water droplets in oil (eg. butter, skin cream, margarine).

There are two ends in an emulsion:

Hydrophillic: water-loving end. They form chemical bonds with water, NOT oils.

Hydrophobic: water-hating end. They form chemical bonds with oil, NOT water.