Pigments pt 2 (Carotenoids-Betalains) Flashcards
1
Q
what classes of organisms are sources of carotenoids?
A
plants, mammals, & microorgs
2
Q
what colors are carotenoids responsible for
A
yellow, orange, red-orange
3
Q
list some animal sources of carotenoids
A
milk fat, egg yolk, butter, salmonids, crustacean species
4
Q
list some microbial sources of carotenoids
A
fungi, yeasts, algae
5
Q
the basic, repeating unit of a carotenoid is called a _____ unit
A
isoprene
6
Q
list 3 examples of hydrocarbon carotenoids
A
b-carotene, a-carotene, lycopene
7
Q
b-carotene gives _____ molecules of vitamin a and is therefore classified as __-______
A
2, pro-vitamin
8
Q
list examples of cyclic carotenoids
A
b-carotene, a-carotene, lutein, canthaxanthin, astaxanthin, cryptoxanthin, zeaxanthin
9
Q
name hydrocarbon carotenes
A
b-carotene, a-carotene, lycopene
10
Q
name oxy-carotenoids
A
lutein, canthaxanthin, astaxanthin, cryptoxanthin, zeaxanthin
11
Q
list sources of lutein
A
green leaves and egg yolk
12
Q
regarding luteins structure…
symmetry of lutein:
rings are _____
A
asymmetrical; hydroxylated
13
Q
list sources of canthaxanthin
A
microorganisms, plants & animals (mushroom, red pepper, brine shrimp & flamingo)
14
Q
isoprene units have _____ double bonds, which enables carotenoids to serve as _____
A
conjugated, antioxidants
15
Q
a-carotene yields ___ unit(s) of vitamin a
A
one
16
Q
lutein has ___ unit(s) of vitamin a
A
0 - ring structures have hydroxyl groups
17
Q
canthaxanthin has ____ unit(s) of vitamin a
A
0 - the ring structures have quinone groups
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
19
Q
does canthaxanthin have antioxidant activity?
A
yeah, high.
20
Q
what are sources of astaxanthin?
A
salmonids, crustaceans, redfish, ocean perch, red snapper
21
Q
can astaxanthin be produced by chemical synthesis?
A
yes
22
Q
which is more stable: canthaxanthin or astaxanthin?
A
astaxanthin
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
24
Q
list sources of cryptoxanthin
A
peaches, yellow corn, egg yolk
25
cryptoxanthin has ___ unit(s) of vitamin A
1
26
list sources of zeaxanthin
widely distributed in nature; major carotenoid in yellow corn and egg yolk
27
zeaxanthin has ___ unit(s) of vitamin A
0
28
true or false: carotenoids are lost to cooking water
false. they are hydrophobic
29
what are some causes of destruction for carotenoids?
- presence of O2, lipoxygenases
- light
- dehydration
30
solubility of anthocyanins?
water soluble
31
what colors are anthocyanins responsible for?
red, blue, violet
32
what is the basic structure for an anthocyanin called? describe it?
flavilium: 2 adjacent rings and one benzene ring attached by a single bond
33
what are 2 similarities between anthocyanins and flavonoids?
- both comprised of 2 ring systems
| - can have conjugated double bonds
34
conjugated db are (always/sometimes) present in anthocyanins, and (always/sometimes) in flavonoids
always; sometimes
35
what functional group is attached to ring system B in anthocyanins?
OH
36
what functional group is attached to ring system B in flavonoids?
caboxyl
37
which are the more potent antioxidants? anthocyanins or flavonoids?
flavonoids. their carboxyl group offers stronger electronegativity that promotes the scavenging of free radicals
38
which are better metal chelators? anthocyanins or flavonoids?
flavonoids bc C=O
39
anthocyanins are _____ esters of _____
sugar esters of anthocyanidin
40
what kind of structure can the OH groups of anthocyanins produce?
OH can bond with sugar units, creating a glycoside
41
an anthocyanin without a sugar moiety is called a(n) _____
aglycone
42
flavonoids/anthocyanins can be classified based on number of sugar residues. what are the categories called?
- monoside (1 monosaccharide)
- bioside (2 monosaccharides or 1 disaccharide)
- trioside
43
what part of an anthocyanin's chemical structure enable it to act as a radical scavenger?
heterocyclic conjugated ring structure
44
what part of an anthocyanin's chemical structure enable it to act as a metal chelator?
O atoms
45
true or false: anthocyanins can serve as a substrate for enzymatic browning
true: they have phenol groups that serve as substrate
46
what destroys anthocyanins?
- extreme pH
- temperature treatments
- some preservatives decolorize (H2O2, sulfites, ascorbic acid)
- high sugar content and presence of O2
47
true or false: binding of anthocyanins to metals can lead to color change.
true
48
true or false: anthocyanins can be lost to cooking waters
true: they're water soluble
49
what enzyme breaks down anthocyanins? how? is there a way to control it?
anthocyanase. it breaks down glycosidic bonds. control by microwave heating.
50
name the monosaccharides you can find on anthocyanins
D-glucose, D-galactose, L-arabinose, D-xylose & L-rhannose
51
name the disaccharides you can find on anthocyanins
gentiobiose, rutinose, sophorose, neohesperidose
52
name the trisaccharides you can find on anthocyanins
gntiotriose, xylosylrutinose, glucosylrutinose
53
name common anthocyanins
- cyanidin
- delphinidin
- malvidin
- pelargonidin
- peonidin
- petunidin
54
color & sources of cyanidin?
orange-red
| apples, cherries, oranges, plums, raspberries, and cabbage
55
color & sources of delphinidin?
blue-red
| grapes and oranges
56
color & sources of malvidin
blue-red
| blue grapes
57
color & sources of pelargonidin?
orange
| strawberries
58
color & sources of peonidin?
orange-red
| cherries & plums
59
color & sources of petunidin?
blue-red
| blueberries
60
what's the effect of adding OH and methoxy (-OCH3) to anthocyanins?
adding OH increases blue
adding methoxy increases red
61
why does acidic conditions make anthocyanins red?
favors glycosidic bonding with sugars, imparting red
62
what does the presence of metals do to anthocyanins?
form purple or gray colors. Ex) pears turn greyish with interaction of sugars and metal from tin cans
63
what causes the "pinking" of canned pears?
oxidation of normally colorless forms of anthocyanins in the presence of oxygen
64
how does glucosidase affect anthocyanins?
removes sugars, destabilizing the molecule and causing loss of color
65
solubility of flavonoids?
water soluble
66
what is the most abundant source of polyphenols in the diet?
flavonoids
67
what's the middle ring of a flavonoid called?
benzopyrone
68
general chemical structure of flavonoids?
glycosides with benzoypurone nucleus
69
what's the most common sugar associated with flavonoids?
rutinose
70
what colors are flavonoids responsible for?
dark red, blue, and purple
71
which has greater coloring power: anthocyanins or flavonoids?
anthocyanins
72
sources of flavnoids?
plants, yeasts and fungi
73
what are the categories of flavonoids?
- flavones
- isoflavones
- flavonols
- flavanones
- flavanonols
74
chemical feature of flavones
double bond at 2:3 position
75
chemical feature of isoflavones
benzene ring at 3 position
76
chemical feature of flavanols
OH group at 3 position
77
chemical feature of flavonones
no double bond at 2:3 position
78
chemical feature of flavanonols?
-OH group at 3 position, no double bond at 2:3 position
79
list some common flavonoids
- apigenin
- genistein
- quercetin
- naringenin
- xeractinol
80
properties of apigenin?
- yellow
- in many F&V (celery and chamomile tea)
- pleasant smell
- bitter & astringent taste
- calming effect/reduces anxiety in some ppl
81
what is astringency?
dry sensation felt in mouth. happens because protein molecules in saliva are precipitated, resulting in loss of their lubricating effects.
82
properties of genistein?
- colorless
- found in many F&V (legumes like soy, alfalfa, peas)
- bitter taste
- estrogenic effects: protects against osteoporosis and menopause symptoms (hot flashes)
83
properties of quercetin?
- yellow/brown
- ubiquitously found in F&V (onion, leaves & grains)
- bitter/astringent taste (immature apples)
84
properties of naringenin?
- colorless
- very bitter
- responsible for bitterness of grapefruits
85
properties of xeractinol?
- colorless
- found mostly in leaves
- bitter and astringent
86
what are some common properties of flavonoids?
- 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
why do flavonoids exhibit pro-vitamin C activity?
Flavonoids affect the absorption of vitamin c. Because flavonoids can directly scavenge free radicals, they may "spare" vitamin C and increase its bioavailability.
88
sources of betalains?
plants and microorganisms. mostly beet plants, but also cranberries, chard, and flower plants.
89
solubility of betalains?
water
90
effect of cooking waters on betalains?
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
true or false: betalains are not glycosides
false, they are
92
what betalains are responsible for red and yellow colors?
```
red = betanin
yellow = vulgaxanthin
```
93
solubility of tannins?
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
color of tannins?
colorless, yellow, or brown
95
what are 2 common tannins?
gallic acid, ellagic acid
96
properties of tannins?
- contribute to astringency in foods
| - participate in enzymatic browning reactions
97
solubility of quinones?
water soluble
98
what similarity(ies) do quinones have with flavonoids/anthocyanins/betlains
none, because they have a dione structure that isn't present in the other mentioned pigments
99
sources of quinones?
plants and microorganisms
100
sources of tannins?
grapes, pomegranates, many berries, apples, sorghum, barley, nuts, chocolate, rhubarb, squash and legumes, such as chickpeas and beans, also contain tannins
101
color of quinones?
yellow to black
102
name 2 common quinones
emodin, spinulosin
103
applications of quinones?
- natural dyestuffs
| - purgatives
104
why can quinones be used as purgatives?
large concentrations can irritate the GI tract.
105
sources of xanthones?
plants (esp mango)
106
properties of quinones
- free radical scavenger
- metal chelator
- substrate for enzymatic browning (due to presence of OH groups)
107
color of xanthones?
mostly yellow
108
solubility of xanthones?
water soluble
109
name a common xanthone
mangiferin
110
true or false: xanthones are glycosides and therefore similar to flavonoids and quinones
true
111
can xanthones act as antioxidants?
| can they serve as substrate for enzymatic browning?
yes and yes
112
sources of melanin/melanoidins
F&V, fungi (mushrooms) and crustacea
113
color of melanin/melanoidins?
brown
114
how are melanin/melanoidins formed?
polymerization of phenolic compounds by PPO and Cu++
115
when is formation of melanins undesirable?
undesirable: discoloration in potatoes and apples
116
what are the 3 products formed by caramelization?
- caramellan
- caramellen
- caramellin
