C1.6 Flashcards
How is lavender oil extracted?
- Plants are put into water and boiled
- Oil and water evaporate together
- Oil is collected as the liquids separate
Why are vegetable oils important foods?
- Provide important nutrients eg vitamin E
- Contain lots of energy
- Can be used as fuels
What does an emulsifier do?
Stops the water and oil separating out into layers
What is an emulsion?
A mixture of oil and water
Why are emulsions useful?
Improves the texture, appearance and coating ability of food
What is meant by hydrophobic and hydrophilic?
Hydrophobic - repelled by water. Has a positive charge
Hydrophilic- attracted to water. Has a negative charge
How do you test for the presence of a double bond?
Add bromine water, if there is a double bond the orange bromine water will go colourless
Does the presence of a double bond mean the oil is saturated or unsaturated?
Unsaturated
How can unsaturated oils be hardened? (Hydrogenation)
Unsaturated vegetable oils can be hardened (double bond removed) by reacting them with hydrogen at 60*C with a nickel catalyst.
What steps are required to extract oils from fruits, seeds and nuts?
- 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
Why are plant oils used in cooking?
They have higher boiling points than water so they cook food at higher temperatures and therefore more quickly
What are properties of saturated fats?
~ Solid at room temp
~ Higher melting points
~ Come from animals
~ Less healthy (high cholesterol)
What are properties of unsaturated fats?
~ Liquid at room temp
~ Lower melting points
~ Come from plants
~ Healthier
Do saturated fats have double bonds?
No
What’s the difference between fats and oils?
~ Fats are solid
~ Oils are liquid
What is hydrogenation?
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
What are 2 things that require emulsions to stop vegetable oils and water from separating?
Salad dressing and ice cream
Why does a salad dressing without an emulsifier not stay mixed for very long?
Because the water particles clump together and the oil particles clump together, leaving the mixture as two separate layers
Why are unsaturated oils hardened into more saturated oils through hydrogenation?
~ 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
What’s an example of hydrogenation?
When ethene and hydrogen are heated together in the presence of a nickel catalyst at 60*C to produce ethane
What is a disadvantage to hydrogenation?
Hydrogenation of vegetable oils makes them less healthy to eat
