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Food Science > Food Emulsions and Foams > Flashcards

Food Emulsions and Foams Flashcards

1
Q

What needs to be stabilized by adding emulsifiers or stabilizing agents?

A

Food emulsions

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2
Q

What contains gas dispersed into liquid?

A

Food foams

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3
Q

w/o

A

Butter

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4
Q

o/w

A

Milk

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5
Q

An emulsion is a __________ system containing droplets of one liquid dispersed in another, the two liquids being immiscible.

A

Collodial

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6
Q

What is the dispersed phase of an emulsion?

A

Liquid

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7
Q

True or False. An emulsion must contain an emulsifier.

A

True

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8
Q

Sol is a ______ dispersed in a ______.

A

Solid dispersed in a liquid

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9
Q

Gel is a ______ dispersed in a ______.

A

Liquid dispersed in a solid

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10
Q

What are the three classifications of an emulsifier?

A

cationic, anionic, and non-ionic

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11
Q

What substance enables two normally immiscible liquids to be mixed together without separating on standing?

A

Emulsifier

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12
Q

What is coalescence?

A

Two liquid or gas droplets merge to form one larger droplet.

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13
Q

What are other examples of o/w besides milk?

A

Salad dressing, mayo, cake batter, frozen desserts.

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14
Q

What are other examples of w/o besides butter?

A

Margarine and some icings

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15
Q

What is the continuous phase of o/w?

A

Water

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16
Q

What is the continuous phase of w/o?

A

Oil

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17
Q

The force required to increase the surface area of a liquid or to spread it over a surface is called______.

A

Surface tension

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18
Q

What is interfacial tension?

A

When two phases are studied

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19
Q

The ________ the surface/interfacial tension, the more difficult it is to mix two phases together.

A

higher

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20
Q

What is a surface-active molecule or surfactant?

A

A molecule that reduces the attractive forces between liquid molecules to reduce the surface or interfacial tension.

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21
Q

True or False. Surface-active molecules are amphiphilic.

A

True

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22
Q

What non-food ingredient enables the water molecules to spread much more easily?

A

Detergent

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23
Q

What spices are examples of a surface active molecule?

A

Dry mustard and paprika

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24
Q

Non-surface-active molecules may _______ interfacial tension depending on their ability to bind to the water molecules, hence increasing molecular attraction.

25
When is an emulsion formed?
When oil, water, and an emulsifier are mixed together
26
The liquid with the _______ interfacial tension will tend to form droplets, and the other liquid will flow around the droplets to form the continuous phase.
higher
27
What are the two functions of an emulsifier?
Reduce interfacial tension and form a stable film for protection
28
What is an unstable system with a greater concentration of material in soln than would exist at equilibrium?
Supersaturation
29
What is the dissolution of small crystals or sol particles and the redeposition of the dissolved species on the surfaces of larger crystals or sol particles?
Ostwald ripening
30
What is aggregations?
A process whereby dispersed molecules or particles form aggregates
31
What is the film covers a completely coated emulsion?
Viscoelastic film
32
What promotes emulsion stability by forming a stable interfacial film and preventing coalescence?
Emulsifier
33
True or False. The best emulsifiers are proteins, which uncoil or denature and absorb at the interface.
True
34
What are two examples of a natural emulsifier?
Egg yolk protein and milk caseins
35
Lecithin does ______ usually form strong interfacial films by itself and would not be the emulsifier of choice unless others were added.
Not
36
Low HLB
has more hydrophobic or lipophilic character
37
Does w/o emulsion have a high or low HLB?
low HLB
38
Does o/w have a high or low HLB?
high HLB
39
The cream layer is _____, a true separation of oil and water; it is an emulsion.
Not
40
What factors affect emulsion stability?
Emulsifier, droplet size, storage, pH, viscosity, and ionic strength.
41
Why are proteins the best emulsifier for o/w emulsions?
They are eatable and provide superior resistance against coalescence after emulsification.
42
What conditions favor coalescence?
Freezing, thawing, drying and redispersion.
43
The continuous phase in a foam is _____ than an emulsion.
Thinner
44
How is foam stability measured?
by the loss of foam volume over a period of time
45
__________ viscosity to reduce drainage.
Increase
46
All surfactants are able to reduce surface tension and produce foams, but...
not all are able to form stable films
47
What ingredient increases the liquid viscosity and protects the proteins from excessive denaturation and aggregation at the interface?
Sugar
48
What ingredient leads to a stronger, more stable interfacial film?
Acid
49
What ingredient increases viscosity?
Gums and thickening agents
50
What is the function of foam suppressants?
Suppress the adsorption of the desired foaming agent and prevent it from foaming a stable foam.
51
What is an example of a foam suppressant
egg yolk
52
What is polydimethylsiloxane?
A type of silicon
53
True or False. All emulsifiers are surfactant.
True
54
True or False. All surfactants do not make good emulsifiers.
True
55
What properties does a good emulsifier have?
Readily absorb at the interface of two liquids Reduce the surface tension of each liquid Form a stable interfacial film
56
Why are detergents good cleaning agents?
It enables water molecules to spread easily. Water forms a thin sheet instead of droplets
57
What end of the molecule faces the continuous phase of an o/w emulsifier?
polar hydrophilic end
58
What end of the molecule faces the continuous phase of a w/o emulsifier?
the non-polar hydrophobic end

Food Science (14 decks)

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