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Chemistry C1 > Plant oils > Flashcards

Plant oils Flashcards

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1
Q

What are some examples of oily foods?

A
  • Fish
  • Meat
  • Vegetables
  • Plants (e.g. sunflower oil)
  • Chips/fast food/crisps
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2
Q

What does saturated mean?

A

There are no double bonds

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3
Q

What does polyunsaturated mean?

A

There are many double bonds

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4
Q

What does monounsaturated mean?

A

There is one double bond

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5
Q

Explain how oils are extracted from plants… (lavender oil)
Steam distillation

A
  • Lavender plants are put in a flask
  • Steam is passed into the flask
  • Lavender oil and water evaporate
  • Lavender oil and steam is condensed
  • Lavender oil separates from water
  • Lavender oil and water are collected
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6
Q

Why do we cook with vegetable oil?

A
  • Higher energy content
  • Contrast of crispy outside and fluffy/soft middle from cooking at a higher temperature so the food cooks faster
  • Different/better taste from cooking at a higher temperature with oil
  • Food absorbs the oil
    (- Vegetable oils contain essential fatty acids which the body needs for metabolic processes)
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7
Q

How do we harden oils into spreads?

A
  • Add hydrogen to unsaturated vegetable oil
  • Nickel is used as a catalyst in this reaction at about 60 degrees C
  • Reaction replaces some or all of the carbon=carbon double bonds with single carbon bonds
  • Molecules fit next to each other better so the forces between the molecule increases and the melting point is raised
  • With a higher melting point it becomes a solid at room temperature
  • This is called HARDENING or HYDROGENATION
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8
Q

Where can plant oils be found?

A

Anywhere:

  • petals
  • Leaves
  • Stem
  • Roots etc.
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9
Q

How are plant oils extracted mechanically?

A

Known as cold-pressing where a material is squeezed to extract the oil

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10
Q

What is an example of a plant oil which is extracted mechanically?

A
  • Olive oil
  • Coconut oil
    (essential cooking oils)
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11
Q

How are plant oils extracted by distillation?

A

(For oils more difficult to extract)

Material is dissolved in a solvent and impurities are removed when distilled

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12
Q

What is an example of a plant oil which is extracted by distillation?

A
  • Sunflower oil

- Soy oil

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13
Q

How are plant oils extracted by steam distillation?

A

Steam is passed through the petals and the oils are able to evaporate because they are small and they form an emulsion with water- the oils are then extracted by distillation

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14
Q

What is an example of a plant oil which is extracted by steam distillation?

A
  • Rose oil
  • Lavender oil
    (floral oils)
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15
Q

What are the properties of saturated fats?

A
  • Solid at room temperature
  • (vegetable fats e.g. palm oil)
  • Only carbon-carbon single covalent bonds
  • Addition of bromine water means the orange bromine remains the same colour (no possibility of free bonds)
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16
Q

What are the properties of unsaturated fats?

A
  • Mostly liquid at room temperature (due to carbon=carbon double bonds in their molecules which stop molecules fitting together well)
  • Have carbon=carbon double bonds
  • Monounsaturated= 1 double bond
  • Polyunsaturated= more than 1 double bond
  • Can be hardened/hydrogenated to make spreads
  • Addition of bromine water decolourises the orange of bromine (bonds with free bonds)
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17
Q

What fuel can be made from vegetable oil?

A

Biodiesel

Similar properties to ordinary diesel

18
Q

What kind of saturation are vegetable oils and animal fats?

A

Vegetable oils tend to be unsaturated

Animal fats tend to be saturated

19
Q

Which type of fat is less healthy an why?

A

Saturated compared to unsaturated because saturated fats increase the amount of cholesterol in the blood, which can block arteries and increase the risk of heart disease

20
Q

Which unsaturated fat is healthier: monounsaturated or polyunsaturated?

A

Polyunsaturated

The more double bonds there are, the easier it is for our body to break down and digest the fat

21
Q

What is a health benefit of natural unsaturated fats such as olive oil and sunflower oil?

A

Help reduce the amount of cholesterol

22
Q

Are trans fats (partially hydrogenated vegetable oil) healthy?

A

No
Increases the amount of cholesterol in the blood increasing the risk of heart disease
This is due to the fact that the double carbon bonds have been lost

23
Q

What is an emulsion?

A

A mixture of oil and water where the oil droplets are very small

24
Q

How is milk an emulsion?

A
  • Contains proteins, which are emulsifiers

- Emulsifiers separate the oil and water so they combine evenly

25
Q

What are examples of where emulsifiers are used?

A
  • Mayonnaise (sunflower/olive oil and vinegar)
  • Ice cream
  • Paints
  • Cosmetics
26
Q

What are the pros and cons of using emulsifiers?

A

Pros:
- Stop emulsions separating out, giving them a longer shelf-life
- Allows food companies to produce foods which are lower in fat but which still have a good texture
Cons:
- Some people are allergic to certain emulsifiers e.g. egg yolk

27
Q

How do emulsifiers help oil and water mix?

A
  • The molecule has a hydrophilic head which is attracted to water
  • It also has a hydrophobic tail which is attracted to the oil
  • The hydrophilic head has a negative charge in order to repel other molecules so there is an even spread of the emulsion
28
Q

What are emulsifiers?

A

Chemicals that can help break down fats up into smaller globules so they don’t settle out of suspension

29
Q

What are E numbers?

A

The code on additives for different purposes- each single additive has its own code so that it can be identified internationally (in Europe)

30
Q

What are additives?

A

Chemicals added to improve food (appearance, shelf-life, taste etc.)

31
Q

What is an E1 additive? What does it do? What is an example?

A

Colour

  • Improves food appearance
  • Classes of colour: 1- natural, 2- browning (cooking and processing) 3- additives
  • e.g. E150- caramel, a brown colouring
32
Q

What is an E2 additive? What does it do? What is an example?

A

Preservatives

  • Helps food keep longer
  • Foods go bad quickly without and wastage of food is a big problem so they are added
  • e.g. E211- sodium benzoate
33
Q

What is an E3 additive? What does it do? What is an example?

A

Antioxidants

  • Helps stop food reacting with oxygen which can affect food badly (apple turns brown when it reacts with oxygen)
  • e.g. E300- vitamin c
34
Q

What is an E4 additive? What does it do? What is an example?

A

Emulsifiers, thickeners and stabilisers

  • Helps improve food texture (an example in jam and soya proteins used for making vegetarian products)
  • e.g. E440- pectin
35
Q

What is an E5 additive? What does it do? What is an example?

A

Acidity regulators

  • Helps to control pH
  • Essential part of taste (all fruits contain sugar but without acid they would be sickly and dull)
  • e.g. E501- potassium carbonate
36
Q

What is an E6 additive? What does it do? What is an example?

A

Flavourings

  • 5) sweet, sour, bitter, salty, savoury
  • Subtle blend together with smell released
  • e.g. E621- monosodium glutamate
37
Q

How can we separate dyes in food colouring?

A

Chromatography

38
Q

Why do we use chromatography to test food colourings?

A
  • To see how well they dissolve in a particular solvent

- To check the colourings are safe by matching up to already known substances

39
Q

How can we analyse food colourings?

A

Mass spectrometer

  • identifies elements
  • measures the relative formula mass of the substances given
  • then you can identify the sample to check it is legal and safe
40
Q

What is the texture of an emulsion relative to its counterparts of oil and water?

A

It is generally thicker than either

Chemistry C1 (7 decks)

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