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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.

A

increase

25
Q

When is an emulsion formed?

A

When oil, water, and an emulsifier are mixed together

26
Q

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.

A

higher

27
Q

What are the two functions of an emulsifier?

A

Reduce interfacial tension and form a stable film for protection

28
Q

What is an unstable system with a greater concentration of material in soln than would exist at equilibrium?

A

Supersaturation

29
Q

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?

A

Ostwald ripening

30
Q

What is aggregations?

A

A process whereby dispersed molecules or particles form aggregates

31
Q

What is the film covers a completely coated emulsion?

A

Viscoelastic film

32
Q

What promotes emulsion stability by forming a stable interfacial film and preventing coalescence?

A

Emulsifier

33
Q

True or False. The best emulsifiers are proteins, which uncoil or denature and absorb at the interface.

A

True

34
Q

What are two examples of a natural emulsifier?

A

Egg yolk protein and milk caseins

35
Q

Lecithin does ______ usually form strong interfacial films by itself and would not be the emulsifier of choice unless others were added.

A

Not

36
Q

Low HLB

A

has more hydrophobic or lipophilic character

37
Q

Does w/o emulsion have a high or low HLB?

A

low HLB

38
Q

Does o/w have a high or low HLB?

A

high HLB

39
Q

The cream layer is _____, a true separation of oil and water; it is an emulsion.

A

Not

40
Q

What factors affect emulsion stability?

A

Emulsifier, droplet size, storage, pH, viscosity, and ionic strength.

41
Q

Why are proteins the best emulsifier for o/w emulsions?

A

They are eatable and provide superior resistance against coalescence after emulsification.

42
Q

What conditions favor coalescence?

A

Freezing, thawing, drying and redispersion.

43
Q

The continuous phase in a foam is _____ than an emulsion.

A

Thinner

44
Q

How is foam stability measured?

A

by the loss of foam volume over a period of time

45
Q

__________ viscosity to reduce drainage.

A

Increase

46
Q

All surfactants are able to reduce surface tension and produce foams, but…

A

not all are able to form stable films

47
Q

What ingredient increases the liquid viscosity and protects the proteins from excessive denaturation and aggregation at the interface?

A

Sugar

48
Q

What ingredient leads to a stronger, more stable interfacial film?

A

Acid

49
Q

What ingredient increases viscosity?

A

Gums and thickening agents

50
Q

What is the function of foam suppressants?

A

Suppress the adsorption of the desired foaming agent and prevent it from foaming a stable foam.

51
Q

What is an example of a foam suppressant

A

egg yolk

52
Q

What is polydimethylsiloxane?

A

A type of silicon

53
Q

True or False. All emulsifiers are surfactant.

A

True

54
Q

True or False. All surfactants do not make good emulsifiers.

A

True

55
Q

What properties does a good emulsifier have?

A

Readily absorb at the interface of two liquids
Reduce the surface tension of each liquid
Form a stable interfacial film

56
Q

Why are detergents good cleaning agents?

A

It enables water molecules to spread easily. Water forms a thin sheet instead of droplets

57
Q

What end of the molecule faces the continuous phase of an o/w emulsifier?

A

polar hydrophilic end

58
Q

What end of the molecule faces the continuous phase of a w/o emulsifier?

A

the non-polar hydrophobic end

Food Science (14 decks)

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