Transcript Plant oils and their uses

AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Plant oils and
Plant their
oils and
their
uses
uses
Hodder Education Revision Lessons
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Overview
• Many plants produce useful oils that can be converted into
consumer products including processed foods.
• Emulsions can be made and have a number of uses.
• Vegetable oils can be hardened to make margarine.
• Biodiesel fuel can be produced from vegetable oils.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Plant oils and their uses 1
Some fruits, seeds and nuts are rich in oils that can be
extracted.
The plant material is crushed and the oil removed by pressing.
Alternatively, the oil is dissolved in a solvent such as hexane and
then the solvent is distilled off leaving the oil behind.
Water and other impurities are removed.
What is meant by cold-pressed virgin olive oil?
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Plant oils and their uses 2
What part of the plant
Plant oil
does the oil come from?
Olive oil
Fruit
Rape oil
Seeds
Peanut oil
Nut (food store for seeds)
Avocado oil
Fruit
Jojoba oil
Seed
Palm oil
Fruit
Why isn’t oil
extracted from the
leaves of plants?
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Plant oils and their uses 3
Vegetable oils are important
foods and fuels because
they provide a lot of energy.
They also provide us with
nutrients.
What nutrients do plant oils
contain?
carpathian/Fotolia
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Plant oils and their uses 4
Viktor/Fotolia
Liaurinko/Fotolia
Vegetable oils have higher boiling points than water and so can
be used to cook foods at higher temperatures than by boiling.
This produces quicker cooking and different flavours, but it
increases the energy that the food produces when it is eaten.
Why are you more likely to put on weight if you eat a lot of chips
than if you eat boiled potatoes?
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Emulsions 1
Oils do not dissolve in water. They can be used to produce
emulsions — tiny droplets of oil suspended in water.
Emulsions are thicker than oil or water and have many uses that
depend on their special properties.
What uses do emulsions have?
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Emulsions 2
Emulsions provide better texture, coating ability and
appearance, for example in
•
•
•
•
salad dressings
ice creams
cosmetics
paints
Emulsifiers have hydrophilic and hydrophobic properties.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Emulsifiers
Emulsifiers are used to make emulsions stable. They have
hydrophilic (water loving) and hydrophobic (water hating)
properties.
Explain how emulsifiers work.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Saturated and unsaturated oils 1
Unsaturated vegetable oils contain carbon–carbon double bonds.
They are sometimes called polyunsaturated fats.
Unsaturated fats can be detected by reacting with bromine
water. Bromine water turns from orange-brown to colourless
when it reacts with unsaturated fats.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 6
Saturated and unsaturated oils 2
Unsaturated vegetable oils can be hardened to make them
spreadable by reacting them with hydrogen in the presence of a
nickel catalyst at about 60°C.
Hydrogen adds to the carbon–carbon double bonds.
Hydrogenated oils have higher melting points so they are solids
at room temperature, making them useful as spreads and in
cakes and pastries.
What hydrogenated oils are there?
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