L6: Collodial Systems 🧊💧💨

Question 1

What is a colloid?

Answer 1

Can be any combination of a solid, liquid and gas to create another product

Question 2

What is a solution?

Answer 2

What is made when a solute is dissolved into a liquid (solvent) eg. Water

Question 3

Unlike a solution, the molecules in a colloid..

Answer 3

Don’t dissolve

Question 4

What is a suspension?

Answer 4

A state where particles of a substance are mixed with liquid but undissolved
Eg. Flour and water

Question 5

Unlike a suspension, the molecules in a colloid …

Answer 5

Don’t separate

Question 6

What are the 2 colloidal systems?

Answer 6

Emulsions and foams

Question 7

What is an emulsion?

Answer 7

When 2 unmissable liquids are forced together (eg. Oil and water)

Question 8

What are the 2 types of emulsion

Answer 8

Unstable and stable

Question 9

What does an unstable emulsion do?

Answer 9

Separates (a suspension)

Question 10

Examples of unstable emulsions

Answer 10

Salad dressing
Vinaigrette

Question 11

What does a stable emulsion need?

Answer 11

An emulsifier to hold it together

Question 12

What are the 2 types of stable emulsions? What is the difference?

Answer 12

1. Oil in water
2. Water in oil
   The difference is which is the largest part

Question 13

In milk what is the largest part?
What sits in it?
What has happened?

Answer 13

Water
Oil sits in it
Suspended but doesn’t separate

Question 14

What is mayonnaise?

Answer 14

A stable emulsion

Question 15

What stabilises mayonnaise?

Answer 15

A protein called lecithin, found in the yolk

Question 16

Where is lecithin found?

Answer 16

In the yolk

Question 17

What stabilises vegan mayonnaise ?

Answer 17

Aquafaba or liquid from a can of chickpeas

Question 18

What is the 2 types of food additives?

Answer 18

Preservatives and emulsifiers/stabilisers

Question 19

What is preservatives function?

Answer 19

To prevent the food from becoming spoiled by microorganisms and to increase its shelf-life so that it is edible for a longer period of time.

Question 20

What are emulsifiers/stabilisers used for/function?

Answer 20

To develop certain textures in foods so that the food does not change (is stable) while it is being stored or used.
Emulsifiers are used to prevent oil and water from separating out in products such as salad dressings

Question 21

Possible side effects of preservatives:

Answer 21

Some people are allergic to some preservatives and need to avoid those foods that contain them.

Question 22

Possible side effects of stabilisers/ emulsifiers:

Answer 22

Side effects are not common with these types of additives.

Question 23

Name and E numbers of preservatives

Answer 23

Potassium sorbate E202
Sodium metabisulphite E223
Sodium nitrate E251
Sodium propionate E281
Sodium benzoate E21.1

Question 24

Name and E-number of emulsifiers/stabilisers

Answer 24

Lecithins (emulsifiers) 322
Carrageenan E407
Guar gum E412

Question 25

What is a foam (colloidal system)?

Answer 25

Where a gas is trapped into a liquid (gas in liquid foam)

Question 26

How do you create a foam?

Answer 26

Whisking egg denatures (breaks down) the protein to create a foam

Question 27

If left, dentauration is..

Answer 27

Reversible and the foam will collapse

Question 28

How do you make a foam stable

Answer 28

Cook it

Question 29

How does foam stabilise

Answer 29

Egg coagulates (sets) when it is heated

Question 30

What are the 3 states of matters?

Answer 30

Solid, liquid and gas