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food chem 2 > Pigments pt 2 (Carotenoids-Betalains) > Flashcards

Pigments pt 2 (Carotenoids-Betalains) Flashcards

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1
Q

what classes of organisms are sources of carotenoids?

A

plants, mammals, & microorgs

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2
Q

what colors are carotenoids responsible for

A

yellow, orange, red-orange

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3
Q

list some animal sources of carotenoids

A

milk fat, egg yolk, butter, salmonids, crustacean species

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4
Q

list some microbial sources of carotenoids

A

fungi, yeasts, algae

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5
Q

the basic, repeating unit of a carotenoid is called a _____ unit

A

isoprene

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6
Q

list 3 examples of hydrocarbon carotenoids

A

b-carotene, a-carotene, lycopene

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7
Q

b-carotene gives _____ molecules of vitamin a and is therefore classified as __-______

A

2, pro-vitamin

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8
Q

list examples of cyclic carotenoids

A

b-carotene, a-carotene, lutein, canthaxanthin, astaxanthin, cryptoxanthin, zeaxanthin

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9
Q

name hydrocarbon carotenes

A

b-carotene, a-carotene, lycopene

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10
Q

name oxy-carotenoids

A

lutein, canthaxanthin, astaxanthin, cryptoxanthin, zeaxanthin

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11
Q

list sources of lutein

A

green leaves and egg yolk

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12
Q

regarding luteins structure…
symmetry of lutein:
rings are _____

A

asymmetrical; hydroxylated

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13
Q

list sources of canthaxanthin

A

microorganisms, plants & animals (mushroom, red pepper, brine shrimp & flamingo)

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14
Q

isoprene units have _____ double bonds, which enables carotenoids to serve as _____

A

conjugated, antioxidants

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15
Q

a-carotene yields ___ unit(s) of vitamin a

A

one

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16
Q

lutein has ___ unit(s) of vitamin a

A

0 - ring structures have hydroxyl groups

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17
Q

canthaxanthin has ____ unit(s) of vitamin a

A

0 - the ring structures have quinone groups

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18
Q

list some applications of canthaxanthin in food industry

A
  • commercially produced by chemical synthesis

- used as feed supplement for cultured salmonids & imitation seafood

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19
Q

does canthaxanthin have antioxidant activity?

A

yeah, high.

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20
Q

what are sources of astaxanthin?

A

salmonids, crustaceans, redfish, ocean perch, red snapper

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21
Q

can astaxanthin be produced by chemical synthesis?

A

yes

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22
Q

which is more stable: canthaxanthin or astaxanthin?

A

astaxanthin

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23
Q

which has higher antioxidant activity? canthaxanthin or astaxanthin?

A

astaxanthin: it is 10 times greater

the OH and keto groups offer greater number of electrons to contribute to scavenging free radicals in addition to its conjugated isoprene skeleton

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24
Q

list sources of cryptoxanthin

A

peaches, yellow corn, egg yolk

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25
Q

cryptoxanthin has ___ unit(s) of vitamin A

A

1

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26
Q

list sources of zeaxanthin

A

widely distributed in nature; major carotenoid in yellow corn and egg yolk

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27
Q

zeaxanthin has ___ unit(s) of vitamin A

A

0

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28
Q

true or false: carotenoids are lost to cooking water

A

false. they are hydrophobic

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29
Q

what are some causes of destruction for carotenoids?

A
  • presence of O2, lipoxygenases
  • light
  • dehydration
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30
Q

solubility of anthocyanins?

A

water soluble

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31
Q

what colors are anthocyanins responsible for?

A

red, blue, violet

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32
Q

what is the basic structure for an anthocyanin called? describe it?

A

flavilium: 2 adjacent rings and one benzene ring attached by a single bond

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33
Q

what are 2 similarities between anthocyanins and flavonoids?

A
  • both comprised of 2 ring systems

- can have conjugated double bonds

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34
Q

conjugated db are (always/sometimes) present in anthocyanins, and (always/sometimes) in flavonoids

A

always; sometimes

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35
Q

what functional group is attached to ring system B in anthocyanins?

A

OH

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36
Q

what functional group is attached to ring system B in flavonoids?

A

caboxyl

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37
Q

which are the more potent antioxidants? anthocyanins or flavonoids?

A

flavonoids. their carboxyl group offers stronger electronegativity that promotes the scavenging of free radicals

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38
Q

which are better metal chelators? anthocyanins or flavonoids?

A

flavonoids bc C=O

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39
Q

anthocyanins are _____ esters of _____

A

sugar esters of anthocyanidin

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40
Q

what kind of structure can the OH groups of anthocyanins produce?

A

OH can bond with sugar units, creating a glycoside

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41
Q

an anthocyanin without a sugar moiety is called a(n) _____

A

aglycone

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42
Q

flavonoids/anthocyanins can be classified based on number of sugar residues. what are the categories called?

A
  • monoside (1 monosaccharide)
  • bioside (2 monosaccharides or 1 disaccharide)
  • trioside
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43
Q

what part of an anthocyanin’s chemical structure enable it to act as a radical scavenger?

A

heterocyclic conjugated ring structure

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44
Q

what part of an anthocyanin’s chemical structure enable it to act as a metal chelator?

A

O atoms

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45
Q

true or false: anthocyanins can serve as a substrate for enzymatic browning

A

true: they have phenol groups that serve as substrate

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46
Q

what destroys anthocyanins?

A
  • extreme pH
  • temperature treatments
  • some preservatives decolorize (H2O2, sulfites, ascorbic acid)
  • high sugar content and presence of O2
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47
Q

true or false: binding of anthocyanins to metals can lead to color change.

A

true

48
Q

true or false: anthocyanins can be lost to cooking waters

A

true: they’re water soluble

49
Q

what enzyme breaks down anthocyanins? how? is there a way to control it?

A

anthocyanase. it breaks down glycosidic bonds. control by microwave heating.

50
Q

name the monosaccharides you can find on anthocyanins

A

D-glucose, D-galactose, L-arabinose, D-xylose & L-rhannose

51
Q

name the disaccharides you can find on anthocyanins

A

gentiobiose, rutinose, sophorose, neohesperidose

52
Q

name the trisaccharides you can find on anthocyanins

A

gntiotriose, xylosylrutinose, glucosylrutinose

53
Q

name common anthocyanins

A
  • cyanidin
  • delphinidin
  • malvidin
  • pelargonidin
  • peonidin
  • petunidin
54
Q

color & sources of cyanidin?

A

orange-red

apples, cherries, oranges, plums, raspberries, and cabbage

55
Q

color & sources of delphinidin?

A

blue-red

grapes and oranges

56
Q

color & sources of malvidin

A

blue-red

blue grapes

57
Q

color & sources of pelargonidin?

A

orange

strawberries

58
Q

color & sources of peonidin?

A

orange-red

cherries & plums

59
Q

color & sources of petunidin?

A

blue-red

blueberries

60
Q

what’s the effect of adding OH and methoxy (-OCH3) to anthocyanins?

A

adding OH increases blue

adding methoxy increases red

61
Q

why does acidic conditions make anthocyanins red?

A

favors glycosidic bonding with sugars, imparting red

62
Q

what does the presence of metals do to anthocyanins?

A

form purple or gray colors. Ex) pears turn greyish with interaction of sugars and metal from tin cans

63
Q

what causes the “pinking” of canned pears?

A

oxidation of normally colorless forms of anthocyanins in the presence of oxygen

64
Q

how does glucosidase affect anthocyanins?

A

removes sugars, destabilizing the molecule and causing loss of color

65
Q

solubility of flavonoids?

A

water soluble

66
Q

what is the most abundant source of polyphenols in the diet?

A

flavonoids

67
Q

what’s the middle ring of a flavonoid called?

A

benzopyrone

68
Q

general chemical structure of flavonoids?

A

glycosides with benzoypurone nucleus

69
Q

what’s the most common sugar associated with flavonoids?

A

rutinose

70
Q

what colors are flavonoids responsible for?

A

dark red, blue, and purple

71
Q

which has greater coloring power: anthocyanins or flavonoids?

A

anthocyanins

72
Q

sources of flavnoids?

A

plants, yeasts and fungi

73
Q

what are the categories of flavonoids?

A
  • flavones
  • isoflavones
  • flavonols
  • flavanones
  • flavanonols
74
Q

chemical feature of flavones

A

double bond at 2:3 position

75
Q

chemical feature of isoflavones

A

benzene ring at 3 position

76
Q

chemical feature of flavanols

A

OH group at 3 position

77
Q

chemical feature of flavonones

A

no double bond at 2:3 position

78
Q

chemical feature of flavanonols?

A

-OH group at 3 position, no double bond at 2:3 position

79
Q

list some common flavonoids

A
  • apigenin
  • genistein
  • quercetin
  • naringenin
  • xeractinol
80
Q

properties of apigenin?

A
  • yellow
  • in many F&V (celery and chamomile tea)
  • pleasant smell
  • bitter & astringent taste
  • calming effect/reduces anxiety in some ppl
81
Q

what is astringency?

A

dry sensation felt in mouth. happens because protein molecules in saliva are precipitated, resulting in loss of their lubricating effects.

82
Q

properties of genistein?

A
  • colorless
  • found in many F&V (legumes like soy, alfalfa, peas)
  • bitter taste
  • estrogenic effects: protects against osteoporosis and menopause symptoms (hot flashes)
83
Q

properties of quercetin?

A
  • yellow/brown
  • ubiquitously found in F&V (onion, leaves & grains)
  • bitter/astringent taste (immature apples)
84
Q

properties of naringenin?

A
  • colorless
  • very bitter
  • responsible for bitterness of grapefruits
85
Q

properties of xeractinol?

A
  • colorless
  • found mostly in leaves
  • bitter and astringent
86
Q

what are some common properties of flavonoids?

A
  • polyphenolic structure (substrate for enz browning)
  • may be involved in in other discoloration reactions (ex: can bind Fe in food to form blue/green colors)
  • chelating agents
  • antioxidant/free radical scavenger
  • pro-vitamin c activity
87
Q

why do flavonoids exhibit pro-vitamin C activity?

A

Flavonoids affect the absorption of vitamin c. Because flavonoids can directly scavenge free radicals, they may “spare” vitamin C and increase its bioavailability.

88
Q

sources of betalains?

A

plants and microorganisms. mostly beet plants, but also cranberries, chard, and flower plants.

89
Q

solubility of betalains?

A

water

90
Q

effect of cooking waters on betalains?

A

some are lost/degraded, but betalains are present in such high concentrations that intense colors still prevail. betalains are often used as food colorants.

91
Q

true or false: betalains are not glycosides

A

false, they are

92
Q

what betalains are responsible for red and yellow colors?

A 
red = betanin
yellow = vulgaxanthin
93
Q

solubility of tannins?

A

some are water soluble, some are water insoluble. it depends on their size: smaller ones tend to be lighter in color and more soluble; larger ones tend to be darker in color and less soluble

94
Q

color of tannins?

A

colorless, yellow, or brown

95
Q

what are 2 common tannins?

A

gallic acid, ellagic acid

96
Q

properties of tannins?

A
  • contribute to astringency in foods

- participate in enzymatic browning reactions

97
Q

solubility of quinones?

A

water soluble

98
Q

what similarity(ies) do quinones have with flavonoids/anthocyanins/betlains

A

none, because they have a dione structure that isn’t present in the other mentioned pigments

99
Q

sources of quinones?

A

plants and microorganisms

100
Q

sources of tannins?

A

grapes, pomegranates, many berries, apples, sorghum, barley, nuts, chocolate, rhubarb, squash and legumes, such as chickpeas and beans, also contain tannins

101
Q

color of quinones?

A

yellow to black

102
Q

name 2 common quinones

A

emodin, spinulosin

103
Q

applications of quinones?

A
  • natural dyestuffs

- purgatives

104
Q

why can quinones be used as purgatives?

A

large concentrations can irritate the GI tract.

105
Q

sources of xanthones?

A

plants (esp mango)

106
Q

properties of quinones

A
  • free radical scavenger
  • metal chelator
  • substrate for enzymatic browning (due to presence of OH groups)
107
Q

color of xanthones?

A

mostly yellow

108
Q

solubility of xanthones?

A

water soluble

109
Q

name a common xanthone

A

mangiferin

110
Q

true or false: xanthones are glycosides and therefore similar to flavonoids and quinones

A

true

111
Q

can xanthones act as antioxidants?

can they serve as substrate for enzymatic browning?

A

yes and yes

112
Q

sources of melanin/melanoidins

A

F&V, fungi (mushrooms) and crustacea

113
Q

color of melanin/melanoidins?

A

brown

114
Q

how are melanin/melanoidins formed?

A

polymerization of phenolic compounds by PPO and Cu++

115
Q

when is formation of melanins undesirable?

A

undesirable: discoloration in potatoes and apples

116
Q

what are the 3 products formed by caramelization?

A
  • caramellan
  • caramellen
  • caramellin

food chem 2 (5 decks)

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