EXAM 2: Emulsions

Question 1

What is the definition of emulsion

Answer 1

The dispersion of two liquids that typically dont blend together (lipids and water)
Use mechanical force or an emulsifying agent to blend

Question 2

Emulsions in food (naturally occurring)

Answer 2

Egg yolks
Dairy products
- milk, cream, butter

Question 3

Emulsions created during cooking or used in manufactured foods

Answer 3

Hollandaise sauce
Beurre blanc sauce
Vinaigrette salad dressing
Mayonnaise
Cheese Sauce
cake batter

Question 4

What are the three classifications of emulsions based on their stability

Answer 4

Permanent Emulsions
Semi-permanent Emulsions
Temporary emulsions

Question 5

What are permanent emulsions

Answer 5

Very stable
Emulsifying agent thoroughly covers all droplets

Food Examples:
Mayonnaise
Hollandaise sauce
Hot dogs

Question 6

What are semi-permanent emulsions

Answer 6

Less stable
Contains stabilizers
- grain Dijon mustard
- honey

Food examples:
Commercial fresh and Italian dressings
Vinaigrette

Question 7

What are temporary emulsions

Answer 7

Least stable
Liquids are blended with shaking

Food examples:
Italian dressing
Oil and vinegar

Question 8

What are factors the influence emulsion stability

Answer 8

Viscosity of the continuous phase
- how thick it is
- the thicker it is the longer it will hold
Size of droplets
- smaller, more evenly sized droplets hold together longer
Presence or concentration of the surfactant (emulsifying agent)
- emulsifying agents help it stay together longer

Question 9

What is the purpose of surfactants

Answer 9

Also called emulsifying agents
Keep immiscible liquids in an emulsion blended
The two types are emulsifiers or stabilizers

Question 10

What are emulsifiers

Answer 10

Type of surfactant
Made by the food industry:
- mono- and diglycerides
- polysorbate 60 and propylene glycol monoesters
Found in foods or extracted from plants (naturally occurring)
- lipoproteins
- egg yolks
- soy lecithin

Question 11

What are stabilizers

Answer 11

Type of surfactant
(Proteins, starch, plant particles)
- grain Dijon mustard
- honey
- pectins (vegetable gums-carrageenan)

Question 12

Why do emulsions break

Answer 12

Liquid to be dispersed is added too quickly to the continuous phase
Too much of the dispersed liquid is added
Sauce gets too hot or too cold