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Food Science > Lecture 4 Starches > Flashcards

Lecture 4 Starches Flashcards

1
Q

What is a starch?

A

A plant polysaccharide stored in roots and seeds of plants and the endosperm of a grain kernel.

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2
Q

What is another name for starch grains?

A

Granules

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3
Q

Starch chains contain long-chain ________ polymers and are insoluble in water.

A

Glucose

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4
Q

True or False. Cooked granules form a temporary suspension when stirred in water.

A

False. Uncooked granules form a temporary suspension when stirred in water.

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5
Q

Which type of starch cooked or uncooked has irreversible swelling?

A

Cooked starch

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6
Q

What cereal grains are good sources of starch in the diet?

A

Wheat, corn and rice

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7
Q

What legumes are good sources of starch in the diet?

A

Soybeans and garbanzo beans

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8
Q

What fruit is a good source of starch in the diet?

A

Bananas

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9
Q

The ______ amount of amylose the stronger the gel.

A

greater

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10
Q

The greater amount of amylopectin content, the _________ the starch paste.

A

More viscous

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11
Q

What makes up ~ 1/4 of starch?

A

Amylose

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12
Q

What makes up ~ 3/4 of starch?

A

Amylopectin

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13
Q

What animal starch is highly branched?

A

Glycogen

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14
Q

What is the animal storage form of carbohydrates?

A

Glycogen

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15
Q

Which is true regarding cereal grains. Cereal grains have a stronger gel or are more viscous?

A

Cereal grains have a stronger gel.

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16
Q

Which is true regarding roots and tubers? Roots and tubers have a stronger gel or are more viscous?

A

More viscous

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17
Q

If starch composition is 100% amylopectin what cannot form?

A

Gel

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18
Q

Uncooked starch can demonstrate what formation?

A

The Maltese cross formation

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19
Q

What is another term for the Maltese cross formation?

A

Birefringence

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20
Q

Why does Maltese cross formation occur?

A

Uncooked starch is a highly ordered crystalline structure, and light is refracted in two directions.

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21
Q

What is imbibition?

A

When starch granules take up water and swell as they are exposed to moist heat.

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22
Q

True or False. Gelatinization occurs in the less dense regions of the start first.

A

True

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23
Q

What process is known for thickening food systems?

A

Gelatinization

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24
Q

During gelatinization short chains of ___________ come out of the granules.

A

Amylose

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25
Q

What is a mechanical force that controls gelatinization?

A

Stirring and agitation

26
Q

During the gelatinization process what is the water-starch mixture called?

A

A sol

27
Q

What is a sol?

A

A colloidal two-phase system containing a liquid continuous phase and a solid dispersed phase

28
Q

A suspension when heated becomes a ______.

A

Sol

29
Q

In gelatinization what type of bond interchange occurs?

A

Hydrogen bonding

30
Q

Granule ________ increases as the temperature increases.

A

swelling

31
Q

To produce viscous pastes or strong gels, starches must first be ____________.

A

Thoroughly gelatinized.

32
Q

What rxn occurs during cooking that results in formed dextrins?

A

Acid hydrolysis

33
Q

True or False. Acid results in less water absorption by the starch granule.

A

True

34
Q

True or False. Exoenzymes are used for industry purposes.

A

True

35
Q

What component in endoenzymes acts anywhere on the starch chain and undamaged starch grains to degrade starch?

A

α-amylase

36
Q

What component in exoenzymes acts on α-1,4 glycosidic linkages from the nonreducing end and damaged amylose or amylopectin chains?

A

β-amylase

37
Q

What causes a delay in hydration and decreased viscosity?

A

Fat and proteins

38
Q

What decreases starch paste viscosity and firmness of the cooked and cooled starch product?

A

Sugar

39
Q

True or False. Sugar competes with starch for water and thus delays the absorption of water by starch granules.

A

True

40
Q

What are other factors requiring control in gelatinization?

A

Salt, temp, type of heat, length of heat.

41
Q

What is synonymous with gelatinization?

A

Pasting

42
Q

How can you measure viscosity?

A

Amylograph

43
Q

When amylose “sets” what forms?

A

A gel

44
Q

After gelatinization what forms a thick sol?

A

Amylopectin

45
Q

Types of starch that form gels.

A

Corn starch, wheat starch, and wheat flour

46
Q

What starches do not form gels?

A

Tapioca and waxy cereals

47
Q

True or False. The gel strength of waxy potato starch is strongly inversely correlated with pH.

A

True

48
Q

What is retrogradation?

A

The disrupted amylose and amylopectin chains gradually reallocate into a different ordered structure

49
Q

True or false. Retrogradation is more likely to occur in a high amylose starch.

A

True

50
Q

What is syneresis?

A

The spontaneous shrinking of a gel with exudation of liquid.

51
Q

What is dextrinization?

A

The process involving the browning of starch foods when subjected to dry heat.

52
Q

Water mixed with an insoluble starch forms what?

A

Slurry

53
Q

Three ways starch can be modified.

A

Chemical, physical, and enzymatic

54
Q

What starch is dispersible in cold water?

A

Pregelatinized starch

55
Q

What is pregelatinized starch?

A

An instant starch that has been gelatinized and then dried

56
Q

What is CWS starch?

A

An instant starch that remains as an intact granule.

57
Q

What type of starch can withstand conditions like low pH and high temp?

A

Cross-linked starches (jello)

58
Q

What is a non food use for modified starches?

A

The great wall of china

59
Q

Why does iodine turn starch blue?

A

The iodine binds to the amylose structure of starch

60
Q

What are uses of starch in food systems?

A

Thickeners, stabilizer, gelling agent, fat replacer

61
Q

What what partially replace fat?

A

Maltodextrins

62
Q

What is resistant starch?

A

Dietary fiber

Food Science (14 decks)

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