Pigments: Anthocyanins, Flavonoids and others Flashcards
(35 cards)
Anthocyanins:
- water or fat soluble?
- plant or animal pigment?
- imparts what 3 colors of various f and veg?
- basic structure/common central group = ?
- water soluble!
- plant pigment
- red, blue and violet
- flavylium ion
how many rings does anthocyanins have?
3 rings!
- 2 are fused together –> benzo 3-hydroxypyran = ring A
- 1 benzene attached to position 2 of the 3-hydroxypyran group = ring B
flavylium ion vs anthocyanidin vs aglycone vs anthocyanins vs glycosides
- flavylium ion = basic structure of anthocyanins
- anthocyanidin and aglycone –> anthocyanin that only has the basic structure (flavylium ion) –> no sugar glycosylated
- anthocyanins = glycosides of anthocyanidin
- glycosides: anthocyanidins that have sugars glycosylated to it
monosides vs biosides vs triosides
- monosides: only 1 sugar glycosylated to anthocyanidins
- biosides: 2 sugars! either 2 monosacs or 1 disac
- triosides: 3 sugars! either 1 trisacs, 1 mono and 1 disacs, or 3 monosacs
examples of sugars of anthocyanins:
- monosacs (5)
- disacs (4)
- trisacs (3)
MONOSACS:
- D-glucose, D-galactose, L-arabinose, D-xylose, L-rhamnose
DISACS:
- gentiobiose, rutinose, sophorose, neohesperidose
TRISACS:
- gentiotriose, xylosylrutinose, glucosylrutinose
difference between gentiobiose and gentiotriose?
- gentiobiose: glycosyl glucose constiting of 2 D-glucopyranose units connected by a b-1-6 linkage
- gentiotriose: 3 D-glucopyranose units connected by b-1-6 linkage –> 3rd glucose is open(?)
4 sources of anthocyanins
- plants (fruits and veg)
- microorganisms
- extraction
- biosynthesis
5 steps for extraction of anthocyanins from natural sources
- source material is pretreated (drying, defatting, grinding/crushing)
- mix/blend powder with solvent for extraction (ie water, acidified water or acidified water + ethanol)
- after extraction, homogenate undergoes heat treatment –> coagulates proteins (coextracted with anthocyanins) + breaks down enzymes like anthocyanases
- extract is filtered to exclude insoluble material –> anthocyanins are collected by adsorption chromatography with amberlight as support material
- purified anthocyanin may be dried to reduce size/volume and have it in a stable form to facilitate transportation/distribution for us in various applications
biosynthesis of anthocyanins
1. which 2 components are condensed together
2.
3.
- malonyl-CoA + Coumaroyl-CoA –> chalcones
- chalcones unergoe series of changes to form various flavonoids (flavones –> hydroxyflavonols)
- flavonoids go on to produce anthocyanidin
- anthocyanidins are glycosylated to produce various anthocyanins
what are 4 different R groups for anthocyanins?
- OH
- methoxyl group (OCH3)
- sugars
- H
what color + which fruits/vegs?
- cyanidin
- delphinidin
- malvinidin
- pelargonidin
- peonidin
- petunidin
- cyanidin: orange-red –> apples, cherries, oranges, plums, raspberries, cabbage
- delphinidin: blue-red –> grapes and oranges
- malvinidin: blue-red –> blue grapes
- pelargonidin: orange –> strawberries
- peonidin: orange-red –> cherries and plums
- petunidin: blue-red –> blueberries
because of _________ nature, anthocyanins can serve as substrates for __________ ________ (by which enzyme?) –> this reaction requires what as coreactant?
- polyphenolic nature
- enzymatic browning by Polyphenol oxidase (PPO)
- O2 as coreactant
anthocyanins:
- increasing OH content enhances which color?
- increasing OCH3 content enhances which color?
- OH –>blue
- OCH3 –> red (ie rosinidin)
effects of handling and processing on anthocyanins:
- pH: acidic vs alkaline results in what color?
- effects of cooking/wash water –> result?
- adding additives like sulfites, ascorbic acid, H2O2?
- processing with metals?
- acidic = OCH3 = red VS alkaline = OH = blue or colorless
- color lost to cooking/wash water bc anthocyanins soluble in water
- anthocyanins can form complexes with sulfites and ascorbic acid = color changes/decolorization
- anthocyanins can chelate metals (Cu, Fe, Zn) –> even colorless forms of pigmentation acquire pinkish, purpleish and grayish colors
- what does high temp do to anthocyanins?
- what does high sugar content do to anthocyanins?
- what does presence of O2 do to anthocyanins?
- anthocyanins are glycosides and glycosidic bonds can be cleaved at high temp = destruction of pigment = color loss
- high [sugar] cause glycosylation of OH groups in molecules and cause destruction of color
- colorless forms of anthocyanins may undergo oxidation in presence of O2 to form colored products (ie pinking of canned pears)
ALSO presence of O2 enhances destruction of anthocyanins (bc of polyphenolic nature
why can anthocyanins scavenge radicals and chelate metal ions?
- what does that make them?
- because of high unsaturation, aromatic form and polyphenolic nature
- serve as antioxidants!
which 2 enzymes can remove sugars from anthocyanins, thus destabilizing the molecule and causing loss of _______
- glucosidases and anthocyanases (split glycosidic linkages)
- loss of color
how to curtail/reduce deletrious effects of glucosidases and anthocyanases?
by microwave bleaching! short time high temp treatment can destroy the enzymes!
- heat treatment not extensive enough to kill pigments
major difference btw anthocyanins and flavonoids?
- 3 similarities?
central unit!
- anthocyanins –> benzo 3-hydroxyl pyran
- flavonoids –> benzopyrone (double bonded O on the right ring of the A ring)
1. both formed via common pathway
2. both can by glycosylated –> both are glycosides
3. both have polyphenolic nature –> both can serve as subtrates in enzymatic browning
flavonoids:
- water or fat soluble?
- found in (2)
- most abundant ________ in the diet
- they are _______ with a ________ nucleus
- also known as _________
- most common sugar attached = ?
- they give certain fruits, veg and herbs their (3) colors
- water soluble
- plants and microorganisms
- polyphenols
- glycosides with a benzopyrone
- anthoxanthins
- rutinose
- dark red, blue and purple
flavonoids are __________ in plants and tend to occur _______, although some plant species may be ________ in particular flavonoids than others
- widespread in plants
- occur together
- may be richer in particular flavonoids
difference between: + examples
- flavones
- isoflavones
- flavonols
- flavonones
- flavononols
- flavones: double bond at 2:3 position + benzene ring at 2 position –> apigenin
- isoflavones: double bond at 2:3 position + benzene ring at 3 position –> genistein
- flavonols: double bond at 2:3 position + OH group at 3 position –> quercetin
- flavonones –> NO double bond at 2:3 position (saturated) + benzene at 2 position –> naringenin
- flavononols –> NO double bond at 2:3 position + OH group at 3 position –> xeractinol
quercetin
- what type of flavonoids?
- causes what feeling in mouth? why?
- present where?
- what color?
- flavonol (double bond at 2:3 + benzene at 2 + OH at 3)
- bitterness + astringency! –> quercetin causes precipitation of proteins in saliva –> gives dry sensation on cheeks and tongue
- ubiquitous but predominant in unripened fruits + Granny Smith apples
- yellow/brown color
what causes bitter taste in grapefruits?
- color?
naringenin –> flavonone
- colorless
