Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

2) Food Chemistry I > Carbohydrates III > Flashcards

Carbohydrates III Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Gourmet Food flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

_________ is a polymer of D-glucose units linked by a B-1,4 glycosidic linkage

A

Cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Human body lacks enzymes capable of hydrolyzing the _____

glycosidic linkage, making _______ indigestible.

A

B-1,4

cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

_______ exists only in a linear form with no branched counterpart.

A

Cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

________ is present as fiber-like bundles which have extensive amounts of crystalline regions - highly organized by _______.

A

Cellulose

hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Cellulose is often accompanied by other carbohydrates, ______, ________ and ______ to form the structural components of most plant tissues

A

hemicelluloses
pectic substances
lignin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Durability of ________ is well-known

A

cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Do enzymes that are capable of hydrolyzing cellulose exist in nature?

A

Yes, but no one has successfully applied them commercially for the production of glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

__________ of cellulose is quite difficult to perform

A

Acid hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

________ is non-nutritive in nature, and can be used for low-calorie products

A

Cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

By controlled hydrolysis, the more amorphous regions of cellulose can be hydrolyzed, leaving behind _______________

A

microcrystalline cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Microcrystalline cellulose can be used as a __________ without contributing calories

A

bulking agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Microcrystalline cellulose can be used as a ________ and ________

A

bulking agent

plating agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a plating agent used for?

A

To convert liquid products into free-flowing powders by adsorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is CMC?

A

Carboxymethyl cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

________ is a methylated derivated of pure cellulose

A

Carboxymethyl cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

CMC is formed by hydrating cellulose in a strongly (acidic/basic) solution, and then reacting it with ___________

A

basic

sodium chloroacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the net result of the CMC reaction?

A

Addition of a carboxymethyl group onto the chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

_______ is a more soluble cellulose polymer that is capable of contributing to the _______ of a solution as well as forming ________

A

CMC
viscosity
weak gels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The properties of CMC can be modified at will based on the __________ and the degree of __________

A

molecular weight of the polymer

derivatization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The presence of ________ groups means that CMC is susceptible to _____ changes

A

carboxyl

pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

______ may precipitate out of solution at its isoelectric point

A

CMC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

If the pH is above the pKa of the carboxyl groups, the CMC polymers (attract/repel) each other

A

repel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The presence of ionized carboxyl groups in CMC allows _____ ions to be used to cross-link the polymers to form a _____

A

divalent

gel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

______ has found wide application in the food industry as a viscosity- enhancing agent that does not contribute any calories.

A

CMC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

______ is used in ice cream where it provides a smooth texture and inhibits ice crystal growth during storage.

A

CMC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

_____________ and _____________ cellulose derivatives are quite soluble and their viscosities are not affected by pH or salts since these derivatives are __________

A

hydroxypropyl cellulose
methyl cellulose
non-ionic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Hydroxypropyl cellulose and methyl cellulose are formed in (acidic/basic) solutions

A

basic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

______ substances are polysaccharides associated with the _________ between plant cell walls

A

Pectic

middle lammella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

__________ act as a binder to hold the cells together

A

Pectic substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

A pectic substance is a complex carbohydrate largely made up of ______________, which can be extracted from plant material

A

polygalacturonic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The basic unit of pectic substances is __________

A

galacturonic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The carboxyl groups of galacturonic acid may be ________ with _______ groups or may be present as a free acid or its _______

A

esterified
methyl
salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the three categories of pectic substances?

A

1) Pectic acids
2) Pectinic acids
3) Pectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

_________ are polymers of predominantly polygalacturonic acid free of methyl ester groups.

A

Pectic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

_________ are polymers of polygalacturonic acid with some degree of methylation (low methoxy pectin).

A

Pectinic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

__________ are polymers of polygalacturonic acid with >50% of the carboxyl groups methylated.

A

Pectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

The categories of pectic substances are based on their degree of the ________ of the ________ groups

A

methylation

carboxyl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The major use of ________ is for the production of jams and jellies, which use sugar to prevent microbial growth by reducing __________.

A

pectin

water activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What must be present for pectin to form a suitable gel? What is the pH range?

A
  • Sugar, acid, water

- 2.8-3.2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

In a pH range of 2.8 to 3.2, the _______ charge of the residual carboxyl groups in pectin is _______, while the sugar competes for water of hydration, which allows the polymers to form a gel

A

repulsive

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Can pectin form a gel without sugar?

A

Yes, but large amounts of pectin are required (sugar is needed to lower water activity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Most pectin is obtained as a by-product of the ______ industry, form which pectin is extracted using dilute ______

A

citrus

acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What determines the quality and price of pectic substances?

A

Degree of methylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Pectin with a DM of 50 serves well for jellies (with/without) suspended material, while for jams (with/without) particles, a DM > 75 is required

A

without

with

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Rapid setting pectin has a (higher/lower) DM

A

higher

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

High-DM pectin requires special extraction procedures and will set at (higher/lower) temperatures

A

higher

47
Q

________ pectin is useful in preventing particulate material from settling out

A

High-DM

48
Q

_________ pectins, such as _____ and ______, are useful in the manufacture of diet jams and jellies

A

Low-methoxy
pectic
pectinic acids

49
Q

Low-methoxy pectins are produced by controlled hydrolysis of the ______ groups using (acid/alkaline) conditions

A

methyl

alkaline

50
Q

The enzyme _________ may hydrolyze methyl groups to produce low-methoxy pectins

A

pectin methyl esterase

51
Q

______ and _________ are capable of producing a gel with divalent ions to cross-link the polymers at the carboxyl groups

A

CMC

low-methoxy pectins

52
Q

Are sugars required to form a gel in low-methoxy pectins? Why/Why not?

A
  • No

- Owing to the cross-linking of the polymers

53
Q

The pH range for gel formation is much broader in ________ pectins

A

low-methoxy

54
Q

In low-methoxy pectins, for diet products to be shelf-stable, __________ are generally required to compensate for the osmotic effect (water activity reduction) that is lost when _____ is not used in the product.

A

antimicrobial agents

sugar

55
Q

Seeds of some plants contain unique polysaccharides called _____.

A

gums

56
Q

Two important seed gums are _______ and __________.

A

guar gum

locust bean gum

57
Q

Guar gum and locust bean gums are both ____________

A

galactomannans

58
Q

Galactomannans are polymers of _______ and ________

A

galactose

mannose

59
Q

Galactomannans consist of a ______ backbone (_____ linkages) with ______ side groups (______ linkages)

A

mannose
B-1,4
galactose
a-1,6

60
Q

______ is derived from a leguminous plant that is widely grown in India and Pakistan.

A

Guar gum

61
Q

In _______, the ratio of mannose to galactose is roughly 2:1

A

guar gum

62
Q

The most important property of guar gum is its ability to hydrate very rapidly in ________ and form a very _______ solution.

A

cold water

viscous

63
Q

_______ is particularly useful in assisting in the rehydration of dry powders used in “instant products”

A

Guar gum

64
Q

In _______ there is a D-galactose branch on the mannose backbone every other mannose unit

A

guar gum

65
Q

In ________ there is a D-galactose branch on the mannose backbone every fourth or fifth mannose unit

A

locust bean gum

66
Q

In ________, the ratio of mannose to galactose is in the range of 4:1 to 5:1

A

locust bean gum

67
Q

________ gum requires more heating to go into solution than _______ gum

A

Locust bean

guar

68
Q

________ is used extensively in ice cream to impart a smooth meltdown and freeze/thaw resistance; also used in the baking industry to produce softer doughs.

A

Locust bean gum

69
Q

From a functional standpoint, _____ gum and _____ gum are largely interchangeable

A

guar

locust bean

70
Q

How does the viscosity of gums change with pH?

A

It doesn’t

71
Q

How is the stability of gums changed with processing?

A

Not very affective

72
Q

Guar gum and locust bean gums are compatible with _____, ______, and other gums

A

starches

cellulose

73
Q

________ and _______ are often used to subtly modify the texture of other gums

A

Guar gum

locust bean gum

74
Q

________ are obtained by wounding specific tropical trees and shrubs and collecting the exudate.

A

Plant exudate gums

75
Q

The main plant exudate gums are _____, _____, _____, and ______

A

arabic
ghatti
karaya
tragacanth

76
Q

________ are all charged heteropolysaccharides

A

Plant exudate gums

77
Q

________ is a polysaccharide consisting of D-galactose, L-arabinose, L-rhamnose and D-glucuronic acid

A

Gum arabic

78
Q

A number of _____ are said to be present in the side chain portions of _________

A

sugars

plant exudate gums

79
Q

Plant exudate gums are charged due to the presence of ________

A

glucoronic acid

80
Q

The distinguishing feature of gum arabic is that it is _____________

A

extremely soluble in water

81
Q

The major use of _________is as a flavor carrier/dispersant.

A

gum arabic

82
Q

________ is commonly used to convert citrus essential oil flavor emulsions to a water-dispersible powder by spray drying.

A

Gum arabic

83
Q

_______ is also extensively used to inhibit sugar crystallization and as a thickener in candies, jellies and chewing gums.

A

Gum arabic

84
Q

Irish moss is a source of ________

A

carrageenan

85
Q

Red algae is a source of ______

A

agar

86
Q

Giant kelp (brown algae) is a source of _________

A

alginates

87
Q

_________ is a polysaccharide composed of D- and L-galactose and 3,6- anhydro-D-galactose units

A

Carrageenan

88
Q

Some of the galactose moieties in _______ are sulfonated

A

carrageenan

89
Q

________, like starch, is made up of two fractions (linear and branched)

A

Carrageenan

90
Q

__________ has the UNIQUE ability to complex with milk proteins to form a very light gel

A

Carrageenan

91
Q

________ is used extensively to suspend insoluble chocolate solids in chocolate milk and also used in ice cream to minimize drip.

A

Carrageenan

92
Q

_____ is similar to carrageenan in composition

A

Agar

93
Q

_______ has the unique ability to form a thermoreversible gel that sets at about 40oC.

A

Agar

94
Q

________ is best known for its use in bacteriological media

A

Agar

95
Q

______ is used as a gelling agent for bakery products, confections, meat and fish products.

A

Agar

96
Q

_______ are made up of largely linear polymers of D-mannuronic and L-glucuronic acids.

A

Alginates

97
Q

Presence of ______ groups makes _______ sensitive to pH and ionic strength of a food system.

A

carboxyl

alginates

98
Q

_______ is extracted in the form of their sodium salts, so that they will be readily soluble.

A

Alginates

99
Q

Similarly to the behavior of carboxymethyl cellulose and low-methoxy pectin, ________ gels can be produced by cross-linking using divalent ions such as ______.

A

alginates

calcium

100
Q

Many microorganisms produce “______” which are extracellular polysaccharides.

A

slimes

101
Q

How do dextrans differ from starch?

A

Glucose units are linked by a-1,6 rather than a-1,4

102
Q

Where are the branch points of dextrans?

A

a-1,3

103
Q

How do dextrans differ from starches?

A

Do not form organized crystalline granules

104
Q

____________ is the most common organism used to produce dextran by fermentation of _______.

A

Leuconostoc mesenteroides

sucrose

105
Q

The chain length and degree of branching of the polymer in _________ can be controlled genetically, therefore, choosing the right _______ allows a range of desired properties

A

dextrans

organism

106
Q

Xanthan gum is a complex heteropolysaccharide produced by _____________

A

Xanthmonous campestris

107
Q

Xanthan gum is made up of D-______, D-______, and D-___________, present in approximately a _____ ratio

A

glucose
mannose
galacturonic acid
3:3:2

108
Q

Xanthmonous campestris can produce ________ from a variety of cheap carbohydrate substrates

A

xanthan gum

109
Q

How does the viscosity of xanthan gum change with temperature?

A

It doesn’t - it has excellent heat stability

110
Q

What is the viscosity of xanthan gum affected by? What happens when it is removed?

A
  • Affected by shear

- Viscosity returns after shear is removed (pseudoplastic)

111
Q

What is the viscosity of xanthan gum independent of?

A
  • Independent of pH
112
Q

_______ gum is very useful in highly acidic foods

A

Xanthan

113
Q

________ will form a gel with locust bean gum in very low concentrations

A

Xanthan gum

114
Q

_______ is very useful in production of instant puddings or gels without the need for heat.

A

Xanthan gum

2) Food Chemistry I (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions