C1.6

Question 1

How is lavender oil extracted?

Answer 1

• Plants are put into water and boiled
• Oil and water evaporate together
• Oil is collected as the liquids separate

Question 2

Why are vegetable oils important foods?

Answer 2

• Provide important nutrients eg vitamin E
• Contain lots of energy
• Can be used as fuels

Question 3

What does an emulsifier do?

Answer 3

Stops the water and oil separating out into layers

Question 4

What is an emulsion?

Answer 4

A mixture of oil and water

Question 5

Why are emulsions useful?

Answer 5

Improves the texture, appearance and coating ability of food

Question 6

What is meant by hydrophobic and hydrophilic?

Answer 6

Hydrophobic - repelled by water. Has a positive charge

Hydrophilic- attracted to water. Has a negative charge

Question 7

How do you test for the presence of a double bond?

Answer 7

Add bromine water, if there is a double bond the orange bromine water will go colourless

Question 8

Does the presence of a double bond mean the oil is saturated or unsaturated?

Answer 8

Unsaturated

Question 9

How can unsaturated oils be hardened? (Hydrogenation)

Answer 9

Unsaturated vegetable oils can be hardened (double bond removed) by reacting them with hydrogen at 60*C with a nickel catalyst.

Question 10

What steps are required to extract oils from fruits, seeds and nuts?

Answer 10

• Farmers collect seeds from plants
• Seeds are crushed and pressed then the oil is extracted
• Impurities are removed
• Oil is processed to make it into a useful product

Question 11

Why are plant oils used in cooking?

Answer 11

They have higher boiling points than water so they cook food at higher temperatures and therefore more quickly

Question 12

What are properties of saturated fats?

Answer 12

~ Solid at room temp
~ Higher melting points
~ Come from animals
~ Less healthy (high cholesterol)

Question 13

What are properties of unsaturated fats?

Answer 13

~ Liquid at room temp
~ Lower melting points
~ Come from plants
~ Healthier

Question 14

Do saturated fats have double bonds?

Answer 14

No

Question 15

What’s the difference between fats and oils?

Answer 15

~ Fats are solid

~ Oils are liquid

Question 16

What is hydrogenation?

Answer 16

Nickel catalyst
Unsaturated fat + hydrogen -> Saturated fat

Where an alkene and hydrogen are heated with a nickel catalyst. This breaks the double bond to produce an alkane

Question 17

What are 2 things that require emulsions to stop vegetable oils and water from separating?

Answer 17

Salad dressing and ice cream

Question 18

Why does a salad dressing without an emulsifier not stay mixed for very long?

Answer 18

Because the water particles clump together and the oil particles clump together, leaving the mixture as two separate layers

Question 19

Why are unsaturated oils hardened into more saturated oils through hydrogenation?

Answer 19

~ To increase the melting point
~ To make them solid at room temperature
~ To make them into spreads
~ This is done by converting double bonds to single bonds

Question 20

What’s an example of hydrogenation?

Answer 20

When ethene and hydrogen are heated together in the presence of a nickel catalyst at 60*C to produce ethane

Question 21

What is a disadvantage to hydrogenation?

Answer 21

Hydrogenation of vegetable oils makes them less healthy to eat