Emulsions

Question 1

What are the 4 emulsions?

Answer 1

Oil-in-water
Water-in-oil
Oil-in-water-in-oil
Water-in-oil-in-water

Question 2

What is in the dispersed phase?

Answer 2

Droplets (fat)

Question 3

What is in the continuous phase?

Answer 3

Dispersion (water)

Question 4

What is homogenisation?

Answer 4

Conversion of 2 immiscible liquids into an emulsion

Question 5

What is a homogeniser?

Answer 5

Mechanical device that causes homogenisation

Question 6

Why is energy required for an emulsions?

Answer 6

To increase size of interface between two phases and increase droplet size

Question 7

How can fluids become miscible?

Answer 7

They have no interfacial tension

Question 8

How can interfacial tension be reduced?

Answer 8

Phospholipids

Question 9

What is temporary homogenisation?

Answer 9

Droplets are deformed and collide but then separate again

Question 10

What is permanent homogenisation?

Answer 10

Droplet deformation and emulsifier adsorption causes stabilisation

Question 11

What are the 3 emulsifier types?

Answer 11

Surfactants
Amphiphilic biopolymers
Electrostatic and steric stabilisation (pickering)

Question 12

What is HLB?

Answer 12

Hydrophilic Lipophilic Balance and is the difference between head and tail on a phospholipid

Question 13

What is CMC?

Answer 13

Critical Micelle Concentration and is the concentration at which a micelle is formed

Question 14

How do surfactants stabilise?

Answer 14

Electrostatic repulsion causes reduction in interfacial tension

Question 15

How do amphiphilic biopolymers work?

Answer 15

Hydrophobic and hydrophilic regions locate in oil and water phase where the emulsifiers change to maximise contact between phases

Question 16

How do Pickering cells stabilise?

Answer 16

Electrostatic and steric (physical) repulsion of oil to prevent coalescence

Question 17

Stability of emulsifiers

Answer 17

Surfactant=low
Amphiphilic=medium
Pickering=high

Question 18

What is gravitation separation?

Answer 18

Separation by density, creaming causes oil to rise, sedimentation causes water to fall

Question 19

What is flocculation?

Answer 19

Association of 2 or more droplets without losing integrity

Question 20

What is coalescence?

Answer 20

Fusion of 2 or more droplets into a larger one

Question 21

What is Oswald ripening?

Answer 21

Mass transfer of dispersed phase of small droplets to large droplets

Question 22

What is phase inversion?

Answer 22

o/w emulsion to w/o or vice versa

Question 23

What is the role of stabilisers?

Answer 23

Thicken and gel
Texture and mouthfeel

Question 24

Reducing flocculation

Answer 24

Increase continuous phase viscosity
Apply charge to droplet surface

Question 25

Reducing Oswald ripening

Answer 25

Narrow droplet size distribution
Triglycerides have negligible solubility in water

Question 26

Reducing coalescence

Answer 26

Increase continuous phase viscosity
Apply charge to droplet surface

Question 27

Reducing sedimentation

Answer 27

Increase continuous phase viscosity
Decrease droplet size
Match density of phases

Question 28

Foam definition

Answer 28

Air bubbles dispersed in water

Question 29

How can foam be formed?

Answer 29

Liquid forced around gas (whipping)
Gas forced through liquid (injection)
Generation of gas (chemical)

Question 30

What is disproportionation?

Answer 30

Diffusion of gas between bubbles

Question 31

What is coalescence of a foam?

Answer 31

Rupture of liquid between bubbles

Question 32

How can you measure foams?

Answer 32

Overrun (whipping percentage)
Foam stability (foam loss percentage)
Foam capacity (air percentage)

Question 33

What is isoelectric point?

Answer 33

The pH at which a molecule carries no net charge