Headings Search Questions 
Vegetable Oils.
Vegetable oils come from many
plants.
Examples are lavender, olive,
palm, rapeseed and sunflower.
The oils contain a lot of energy
and are used as food
(for example in cooking or making emulsions)
or for making fuels (biodiesel).
It is usually the seeds (or
nuts) of a plant
which contain the most oil.
The oil is extracted by
crushing the
seeds
and then squeezing the crushed material (called
pressing).
Some oils are extracted by distillation.
The oil can then be refined (made
purer)
by removing water and other
impurities.
Vegetable oils used in
cooking have a higher
boiling point than water
which boils at 100 °C.
Cooking food at a higher temperature is quicker
and produces different flavours.
The cooked food usually has more energy
because some of the oil remains on the food after
cooking
and some of the water in the cells of the
food becomes replaced by oil.
Eating too much food cooked in oil can make you
overweight
because the oily food has more energy in it than you use during
exercise.
Some vegetable oils are
better for your health
than others.
Oils containing many unsaturated
fats are more healthy
than oils with a large proportion of saturated
fats.
Unsaturated means that the molecule
contains
one or more double
bonds between carbon atoms.
Saturated means that the molecule has no double
bonds.
Bromine can be used to see if
the substance has double bonds.
Palm oil is more saturated and
sunflower oil is
more unsaturated.
Olive oil and rapeseed oil are somewhere in between.
It is possible to make an oil more saturated to make
margarine.
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