Emulsions

Question 1

What are emulsions?

Answer 1

Dispersions of two immiscible liquids (oil and water)

Question 2

What are two different types of emulsions?

Answer 2

Oil-in-water and water-in-oil

Question 3

What are examples of oil-in-water emulsions?

Answer 3

milk, mayo, cream

Question 4

What are examples of water-in-oil emulsions?

Answer 4

butter and margarine

Question 5

Is it possible to make these emulsions by just mixing pure water and oil?

Answer 5

Yes but they easily separate.

Question 6

What must happen in order for emulsions to not separate?

Answer 6

They must be kinetically stable

Question 7

Are emulsions thermodynamically stable?

Answer 7

No, they are high in energy state

Question 8

When can the energy required to create an emulsion be lowered?

Answer 8

When interfacial tension can be decreased

Question 9

How can one decrease oil-water interfacial tension?

Answer 9

Add emulsifiers which have hydrophobic and hydrophilic sides meaning less energy is needed to generate emulsions. They are kinetically stabilized.

Question 10

What are two types of emulsifiers?

Answer 10

Small molecules emulsifiers and plymeric emulsifiers

Question 11

What are some common food emulsifiers?

Answer 11

Lecithin, Tween 20, and monoglyceride

Question 12

What attaches the large globules in homogenized milk?

Answer 12

Dark clumps of casein micellar material on the oil-water interface

Question 13

What stabilizes emulsions?

Answer 13

Proteins, increased viscosity, descreased interfacial tension

Question 14

What are emulsions characterized by?

Answer 14

There average droplet size

Question 15

What are four ways that emulsions are destabilized?

Answer 15

1. Creaming
2. Sedimentation
3. Flocculation
4. Coalescence

Question 16

What are two types of gravitational separation?

Answer 16

Creaming and Sedimentation

Question 17

What is creaming?

Answer 17

When oil droplets are on top because they are less dense than water.

Question 18

What is sedimentation?

Answer 18

When oil droplets are on bottom because they are more dense than water.

Question 19

What is flocculation?

Answer 19

Droplets associate with each other without losing their individual identities meaning they will separate easily.

Question 20

What is coalescence?

Answer 20

Droplets join together irreversibly (oil and water separate)

Question 21

What are two types of droplet aggregation?

Answer 21

Flocculation and coagulation

Question 22

Describe the emulsion making process

Answer 22

Oil and water soluble ingredients are blended together to form a coarse emulsion. They are then homogenized to stabilize and decrease droplet size.

Question 23

Name some oil in water emulsions

Answer 23

milk, salad dressing, coffee creamer, mayo, falvoured beverages

Question 24

Name a oil and air-in water emulsion

Answer 24

Ice cream

Question 25

Name two air in water emulsions (stabilized by fat)

Answer 25

whipped cream and meringue

Question 26

What are 2 water in oil emulsions?

Answer 26

butter (in milk fat) and margarine (in vegetable oil)

Question 27

How is butter made through the emulsification process?

Answer 27

Cream (an oil-in-water) emulsion is churned and the oil droplets coalescence causing the fat and water to separate. The butter milk is removed and butter becomes a water-in-oil emulsion