C1.6 Plant Oils and their Uses

Question 1

What natural materials can we extract oil from? (3)

Answer 1

Some fruits, nuts and seeds

Question 2

How can we extract oil from plant material? (2)

Answer 2

By crushing and pressing it, or using distillation

Question 3

Explain the process of using crushing and pressing to extract oil (2)

Answer 3

Crushed plant materials is pressed between metal plates to squeeze the oil out. A centrifuge is then used to separate the oil from any water/plant material - the oily paste made is spun around at high speeds causing the oil and water to separate

Question 4

Describe the process of distillation to extract oil

Answer 4

The plant material is heated until the oil within it evaporates. The vapour is then collected and condensed into the liquid oil

Question 5

How is the plant material in distillation heated?

Answer 5

Using steam, the steam is passed over the plant material to heat it

Question 6

What is a benefit of using distillation over crushing and pressing?

Answer 6

The oil and water produced in distillation is collected in a funnel with a top on the bottom (a separating funnel), which is an easy way to separate the oil from the water

Question 7

What (health) benefits are there to using plant oils in food? (3)

Answer 7

They have a high energy content, oils from seeds contain vitamin E and vegetable oils contain essential fatty acids

Question 8

What benefits are there to using plant oils to cook? (2)

Answer 8

They have higher boiling points than water so they can be used to cook foods at higher temps which cooks food faster and plant oils intensifies the taste of the food being cooked

Question 9

What drawbacks are there to cooking with plant oils?

Answer 9

They are high in energy - so eating too much cooked in plant oils makes you put on weight

Question 10

Why are plant oils good to use as fuels? (3)

Answer 10

Because they are renewable, carbon neutral and high in energy

Question 11

What are oils and fats made of?

Answer 11

Long-chain molecules with lots of carbon atoms

Question 12

What’s the difference between saturated and unsaturated fats/oils?

Answer 12

Unsaturated fats/oils contain carbon-carbon double bonds

Question 13

What are monounsaturated fats?

Answer 13

They contain one carbon-carbon double in their carbon chains

Question 14

What are polyunsaturated fats?

Answer 14

They contain more than one carbon-carbon double in their carbon chains

Question 15

What is the test for unsaturated fats/oils?

Answer 15

By adding the unsaturated fat/oil to bromine water, if unsaturated, the bromine water will be decolourised from orange

Question 16

Unsaturated oils are liquid at room temperature, how can they be hardened?

Answer 16

By reacting them hydrogen in the presence of a nickel catalyst at about 60̊C - this is hydrogenation

Question 17

What happens to hydrogenated oils?

Answer 17

They lose their double bonds, the hydrogen adds to the carbon-carbon double bonds opening them up

Question 18

Why are unsaturated oils hydrogenated?

Answer 18

Because they have a higher melting point so they are more solid at room temp - making the spreadable e.g. margarine

Question 19

How are hydrogenated oils in industry?

Answer 19

They are used in baking cakes and pastries as they are cheaper than butter and they keep longer - making them cheaper and gives them a longer shelf life

Question 20

What happens if you continue to hydrogenate an oil?

Answer 20

It will contain more saturated fat and will become harder - if products like margarine were too hard, they would be difficult to spread

Question 21

Are vegetable oils saturated or unsaturated?

Answer 21

Unsaturated

Question 22

Are animals fats saturated or unsaturated?

Answer 22

Saturated

Question 23

Why are unsaturated fats healthier than saturated fats?

Answer 23

Because unsaturated fats reduce the amount of cholesterol in the blood, whereas unsaturated fats increase the cholesterol in the blood and increase the risk of heart disease

Question 24

What is oil mixed with water an example of?

Answer 24

An emulsion

Question 25

What are emulsions?

Answer 25

Lots of droplets of one liquid suspended in another liquid

Question 26

How can you make an emulsion?

Answer 26

Examples of emulsions are oil-in-water and water-in-oil, these are made by mixing them together and shaking them

Question 27

What are the properties of emulsions?

Answer 27

They are thicker than the original products

Question 28

What are emulsions used for in food? (5)

Answer 28

Salad dressing, mayonnaise, milk, whipped cream and ice cream

Question 29

Besides in food, what other uses do emulsions have? (2)

Answer 29

Moisturising lotions and paint

Question 30

What are emulsifiers?

Answer 30

Substances which stop the oil and water mixtures from separating

Question 31

What are examples of emulsifiers? (2)

Answer 31

Egg yolk and lecithin

Question 32

What is the structure of an emulsifier molecule?

Answer 32

They have a hydrophilic heads and a hydrophobic tail - the hydrophilic head latches onto water molecules and the hydrophobic tail latches onto oil molecules

Question 33

How do emulsifiers work?

Answer 33

When water and oil is mixed with an emulsifier, the tail latches onto an oil molecule, the head then sticks out of the oil mole’ and latches onto the water making the emulsion stable so it won’t separate

Question 34

What are advantages of emulsifiers? (2)

Answer 34

They stop emulsions from separating giving them a longer shelf life, and it allows food to be produced which is low in fat but still has a good texture

Question 35

What are disadvantages to emulsifiers? (1)

Answer 35

Some people can be allergic to certain emulsifiers