Plant Oils and Emulsions Flashcards

1
Q

How are oils extracted from plants?

A
  1. Crushed to release oil

2. Distilled to purify

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2
Q

Why are vegetable oils used in food?

A
  1. High energy content
  2. Some nutrients
  3. Essential fatty acids
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3
Q

What are advantages to cooking with vegetable oil?

A
  1. Higher boiling point than water - cook at higher temperatures and faster
  2. Gives food flavour
  3. Increases energy content
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4
Q

What can vegetable oils be used for apart from cooking?

A

Fuels.

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5
Q

Why are vegetable oils suitable as fuels?

A

High energy content.

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6
Q

What kind of bonds do unsaturated oils contain?

A

Carbon-carbon double bonds.

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7
Q

What is the test and result for unsaturated oils?

A

Bromine water is decolorised.

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8
Q

What is the difference between monounsaturated and polyunsaturated fats?

A

Monounsaturated fats contain one carbon-carbon double bond, while polyunsaturated fats contain more than one carbon-carbon double bond.

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9
Q

How are unsaturated vegetable oils hydrogenated?

A
  1. Nickel catalyst
  2. 60C
  3. Hydrogen
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10
Q

Why are oils hydrogenated?

A

Solid at room temperature - spreads and baking.

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11
Q

Why are oils partially hydrogenated?

A
  1. Cheaper than butter

2. Keep longer

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12
Q

What is the disadvantage to partially hydrogenated oils?

A

Trans fats are unhealthy.

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13
Q

Why are saturated fats more unhealthy than unsaturated fats?

A

Saturated fats increase the amount of cholesterol in the blood, increasing the risk of heart disease.

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14
Q

What types of fats reduce the amount of blood cholesterol?

A

Natural unsaturated fats, such as olive and sunflower oil.

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15
Q

What is an emulsion?

A

Emulsions are made up of lots of droplets of one liquid suspended in another liquid.

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16
Q

Emulsions are thicker than…

A

… either water or oil.

17
Q

Give an example of a food emulsion.

A
  1. Ice cream
  2. Mayonnaise
  3. Whipped cream
  4. Milk
18
Q

What is an emulsifier?

A

A molecule where one part is attracted to water, and the other part is attracted to oil.

19
Q

Which end of the emulsifier is hydrophilic?

A

The round end.

20
Q

How do emulsifiers work?

A
  1. Hydrophobic end latches onto oil droplet
  2. Other oil droplets are repelled by the hydrophilic end
  3. The emulsion can’t separate out
21
Q

What is the advantage of emulsifiers?

A

Gives them a longer shelf-life, with lower fat.

22
Q

What is the disadvantage of emulsifiers?

A

Allergies (e.g egg yolk)