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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
What is a mechanical force that controls gelatinization?
Stirring and agitation
26
During the gelatinization process what is the water-starch mixture called?
A sol
27
What is a sol?
A colloidal two-phase system containing a liquid continuous phase and a solid dispersed phase
28
A suspension when heated becomes a ______.
Sol
29
In gelatinization what type of bond interchange occurs?
Hydrogen bonding
30
Granule ________ increases as the temperature increases.
swelling
31
To produce viscous pastes or strong gels, starches must first be ____________.
Thoroughly gelatinized.
32
What rxn occurs during cooking that results in formed dextrins?
Acid hydrolysis
33
True or False. Acid results in less water absorption by the starch granule.
True
34
True or False. Exoenzymes are used for industry purposes.
True
35
What component in endoenzymes acts anywhere on the starch chain and undamaged starch grains to degrade starch?
α-amylase
36
What component in exoenzymes acts on α-1,4 glycosidic linkages from the nonreducing end and damaged amylose or amylopectin chains?
β-amylase
37
What causes a delay in hydration and decreased viscosity?
Fat and proteins
38
What decreases starch paste viscosity and firmness of the cooked and cooled starch product?
Sugar
39
True or False. Sugar competes with starch for water and thus delays the absorption of water by starch granules.
True
40
What are other factors requiring control in gelatinization?
Salt, temp, type of heat, length of heat.
41
What is synonymous with gelatinization?
Pasting
42
How can you measure viscosity?
Amylograph
43
When amylose "sets" what forms?
A gel
44
After gelatinization what forms a thick sol?
Amylopectin
45
Types of starch that form gels.
Corn starch, wheat starch, and wheat flour
46
What starches do not form gels?
Tapioca and waxy cereals
47
True or False. The gel strength of waxy potato starch is strongly inversely correlated with pH.
True
48
What is retrogradation?
The disrupted amylose and amylopectin chains gradually reallocate into a different ordered structure
49
True or false. Retrogradation is more likely to occur in a high amylose starch.
True
50
What is syneresis?
The spontaneous shrinking of a gel with exudation of liquid.
51
What is dextrinization?
The process involving the browning of starch foods when subjected to dry heat.
52
Water mixed with an insoluble starch forms what?
Slurry
53
Three ways starch can be modified.
Chemical, physical, and enzymatic
54
What starch is dispersible in cold water?
Pregelatinized starch
55
What is pregelatinized starch?
An instant starch that has been gelatinized and then dried
56
What is CWS starch?
An instant starch that remains as an intact granule.
57
What type of starch can withstand conditions like low pH and high temp?
Cross-linked starches (jello)
58
What is a non food use for modified starches?
The great wall of china
59
Why does iodine turn starch blue?
The iodine binds to the amylose structure of starch
60
What are uses of starch in food systems?
Thickeners, stabilizer, gelling agent, fat replacer
61
What what partially replace fat?
Maltodextrins
62
What is resistant starch?
Dietary fiber

Food Science (14 decks)

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