Plant Oils and Emulsions Flashcards
How are oils extracted from plants?
- Crushed to release oil
2. Distilled to purify
Why are vegetable oils used in food?
- High energy content
- Some nutrients
- Essential fatty acids
What are advantages to cooking with vegetable oil?
- Higher boiling point than water - cook at higher temperatures and faster
- Gives food flavour
- Increases energy content
What can vegetable oils be used for apart from cooking?
Fuels.
Why are vegetable oils suitable as fuels?
High energy content.
What kind of bonds do unsaturated oils contain?
Carbon-carbon double bonds.
What is the test and result for unsaturated oils?
Bromine water is decolorised.
What is the difference between monounsaturated and polyunsaturated fats?
Monounsaturated fats contain one carbon-carbon double bond, while polyunsaturated fats contain more than one carbon-carbon double bond.
How are unsaturated vegetable oils hydrogenated?
- Nickel catalyst
- 60C
- Hydrogen
Why are oils hydrogenated?
Solid at room temperature - spreads and baking.
Why are oils partially hydrogenated?
- Cheaper than butter
2. Keep longer
What is the disadvantage to partially hydrogenated oils?
Trans fats are unhealthy.
Why are saturated fats more unhealthy than unsaturated fats?
Saturated fats increase the amount of cholesterol in the blood, increasing the risk of heart disease.
What types of fats reduce the amount of blood cholesterol?
Natural unsaturated fats, such as olive and sunflower oil.
What is an emulsion?
Emulsions are made up of lots of droplets of one liquid suspended in another liquid.
Emulsions are thicker than…
… either water or oil.
Give an example of a food emulsion.
- Ice cream
- Mayonnaise
- Whipped cream
- Milk
What is an emulsifier?
A molecule where one part is attracted to water, and the other part is attracted to oil.
Which end of the emulsifier is hydrophilic?
The round end.
How do emulsifiers work?
- Hydrophobic end latches onto oil droplet
- Other oil droplets are repelled by the hydrophilic end
- The emulsion can’t separate out
What is the advantage of emulsifiers?
Gives them a longer shelf-life, with lower fat.
What is the disadvantage of emulsifiers?
Allergies (e.g egg yolk)
