C1.6 Plant oils and their uses Flashcards Preview

Chemistry Unit 1 > C1.6 Plant oils and their uses > Flashcards

Flashcards in C1.6 Plant oils and their uses Deck (25)
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1
Q

What are oils removed from?

A
  • Nuts
  • Seeds
  • Fruit
2
Q

Give three examples of oils extracted from plant material

A
  • Rapeseed oil
  • Olive oil
  • Lavender oil
3
Q

How are oils extracted from plants?

A
  • The plant material is crushed
  • Oil is removed by pressing
  • Distillation removes water, solvents and impurities
4
Q

Why are vegetable oils useful in food?

A
  • They provide a lot of energy
  • They provide nutrients e.g vitamin E
  • They contain essential fatty acids for metabolic processes
5
Q

Why are vegetable oils useful in cooking?

A
  • They have a higher boiling point than water so they can be used to cook foods at higher temperatures and at faster speeds
  • They also give food a different flavour by releasing chemicals from food soluble in oil
  • They increase the amount of energy we get from food
6
Q

Why are vegetable oils useful as fuels?

A

They provide a high amount of energy

7
Q

What do unsaturated oils contain (in terms of their bonds)?

A

They contain double bonds between some of the carbon atoms in their carbon chains

8
Q

What is the difference between monounsaturated oils and polyunsaturated oils?

A
  • Monounsaturated = one C=C double bond

- Polyunsaturated = more than one C=C double bond

9
Q

How can bromine water be used to test if an oil is saturated or not?

A

Unsaturated oils will decolourise bromine water

10
Q

Explain how vegetable oils can be hardened with hydrogenation.

A
  • By reacting them with hydrogen
  • In the presence of a nickel catalyst
  • At around 60 degrees c
11
Q

What happens in hydrogenation in terms of bonds?

A

The hydrogen reacts with the double bonded carbons and opens up the double bonds

12
Q

Why are hydrogenated oils more useful?

A

They have higher melting points than unsaturated oils and so are more solid at room temperature, making them useful as spreads and for baking

13
Q

Why is margarine only a partially hydrogenated oil?

A

Full hydrogenation would make it too hard and difficult to spread

14
Q

Why are partially hydrogenated oils often used instead of butter in processed foods?

A
  • They are cheaper

- They keep longer

15
Q

How do vegetable oils in food affect health?

A
  • Natural unsaturated fats reduce the amount of blood cholesterol, reducing the risk heart disease
  • But partially hydrogenated oils, due to “trans” fats, increase the amount of cholesterol in the blood
16
Q

What is the rule for oils and water?

A

They don’t dissolve in each other

17
Q

What is an emulsion?

A

Lots of droplets of one liquid suspended another liquid

18
Q

What are the differences between emulsions and oil/water?

A
  • Thicker
  • Better texture
  • Better coating ability
  • Better appearance
19
Q

Give 4 uses of emulsions.

A
  • Salad dressings
  • Ice creams
  • Cosmetics
  • Paints
20
Q

What are emulsifiers used for?

A

To make sure the oil and water mixture does not separate out

21
Q

What property does the head of an emulsifier have?

A

It is hydrophilic

22
Q

What property does the tail of an emulsifier have?

A

It is hydrophobic

23
Q

Explain how emulsifiers work to ensure oil and water does not separate

A
  • The head latches onto the water molecules
  • The tail latches onto the oil droplets
  • This keeps the oil droplets separate as the heads repel them
  • So the droplets cannot come together keeping the oil and water mixed in together
24
Q

What are the advantages to emulsifiers?

A
  • Gives emulsions a longer shelf-life

- Food can be lower in fat but still have a good texture

25
Q

What is the disadvantage to emulsifiers?

A

Some people are allergic to certain emulsifiers