pigments and other colorants - vscht.cz pigments and... · pigments and other colorants colou red...

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Pigments and other colorants Coloured compounds (colorants, pigments) colour effect based on the selective absorption of certain wavelengths resulting colour is determined by the spectrum of reflected wavelengths of light natural pigments synthetic pigments identical to natural pigments synthetic pigments natural colorants - also derived from natural raw materials by technological processes (caramel) discoloration - undesirable colour change light elmg. radiation visible to the human eye (400-800 nm)

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Page 1: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Pigments and other colorants

Coloured compounds (colorants, pigments)

colour effect based on the selective absorption of certain wavelengths

resulting colour is determined by the spectrum of reflected wavelengths of light

natural pigments

synthetic pigments identical to natural pigments

synthetic pigments

natural colorants - also derived from natural raw materials by technological processes (caramel) discoloration - undesirable colour change

light – elmg. radiation visible to

the human eye (400-800 nm)

Page 2: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

NATURAL COLOURS

formation

primary compounds natural food components natural components of other materials (microorganisms, algae, higher plants) used as additives

secondary compounds enzymatic reactions (non-enzymatic browning reaction) chemical reactions

Page 3: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

important groups

tetrapyrrole colours plants, animals

hem colours

chlorophyll colours

betalain colours plants

betacyans

betaxanthins

flavonoid colours plants

anthocyanins

anthoxanthins

phenolic and quinoid colours plants, animals

phenols

quinones

carotenoid colours plants, animals

carotenes

xanthophylls

Page 4: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

TETRAPYRROLE PIGMENTS (TETRAPYRROLES)

porphyrin pigments (porphyrins) cyclic

hem pigments (haems)

chlorophyll pigments (chlorophylls)

biline pigments (bilines) linear

phycobilins

1

2

34

56

7

8

9

10

11

12

1314

1516

17

18

19

20

NH N

N NH

A B

CD

A B C D1

2 3

4

5

6

7 8

9

10

11

12 13

14

15

16

17 18

19

N

H

N N N

porphyrins bilines

Page 5: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

haem pigments meat, meat products haem (reduced haematin, Fe2+) haemoglobin haematin (Fe3+) myoglobin (P = globin residue,16,8 kDa)

H

(II)

P

H2O

CH2

H3C

N

N

N N

N N

CH3

H3C

CH3

CH2=CH

CH=CH2

HOOCCH2CH2 CH2CH2COOH

Fe

HOOCCH2CH2 CH2CH2COOH

H3C CH3

CH3

H3C

NN

NN

Fe (II)

CH=CH2

CH2=CH

His93

Page 6: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

myoglobin (Mb) dark red

oxymyoglobin (MbO2) scarlet

metmyoglobin (MMb) red to brown

Meat Myoglobin mg.kg-1

Haemoglobin mg.kg-1

Proportion of

haemoglobin (%)

Beef 3140-7020 340-520 6-10

Pork 790-2320 360-1200 25-50

O 2

myoglobin oxymyoglobin

N

Fe

N

N

N

(II)

protein

H2O

N

Fe

N

N

N

(II)

protein

O O

OH

metmyoglobin

N

N

Fe

N

N

(III)

protein

Page 7: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

formation of MMb autoxidation

P-Fe2+ (Mb) + O2 P-Fe3+ (MMb) + O2- (superoxide anion radical)

2 O2- + 2 H+ H2O2 + O2

3+ 3+ 4+ - P-Fe + H2O2 = P-Fe=O P-Fe-O (oxen, hypervalent Fe)

initiation of lipid peroxidation

Page 8: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

reaction of MMb during temperature processing of meat

metmyoglobin globin denaturation (70-80 oC) globin hydrolysis hematin or haem (loss Fe3+ nebo Fe2+) linear tetrapyrroles

Page 9: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

stabilization of meat and meat products colour microflora

meat + NO3- NO2-

2 Mb + NO2- 2 MMb + NO + H2O

Mb + NO MbNO + H2O

heating: MbNO Mb(NO)2 + globin

MbNO = nitroxymyoglobin

Mb(NO)2 = nitroxyhaemochrom (nitrosylhaemochrom, nitroxymyochromogen)

use of ascorbic acid: MMb + H2A Mb + A

fuscous up to green colours (sulfomyoglobin, verdochrom, cholemyoglobin)

Page 10: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

CHLOROPHYLL PIGMENTS green parts of fruits and vegetables porphyrins chlorophylls complex Mg (II) chlorophylls R = CH3 chlorophyll a yellow-green R = CH=O chlorophyll b blue-green without Mg (II) pheophytin without phytol chlorophyllide without Mg (II) and phytol pheophorbide

N N

N N

Mg (II)

CH2=CH

Mg

R

(II)

CH3

CH3 CH3 CH3 CH3O

NN

NN

H3C CH2CH3

CH3

OCH2

H3C

CH2

CO O

C O

CH3 methyl

fytyl

3

1

Page 11: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

reactions of chlorophylls during processing (acids, enzymes)

chlorophylls

strong acid

weak acid

strong acid

strong acid

chlorophyllide

pheophorbide

pheophytin

Chlorophyllase

Page 12: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

colour stabilisation

chlorophylls, Cu complex of chlorophylls - Fat-soluble green dye mixture chlorophyllin (Na and K salts of various compounds) - teal, soluble in

water

Cu complex of chlorophyllin – green stable colorants

+

2 H

- 2 H+

+

Mg

- Mg2+

2+

o

feofytinchlorofyl

N N

N N

Mg (II)

H

H

N N

N N

N N

N N

Cu (II) měďnatý komplex

Cu , - 2H2+

Cu , - Mg 2+ 2+

chlorophyll phaeophytin

Chlorophyll Cu2+ complex

Page 13: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

BETALAIN PIGMENTS

beetroot prickly pear amaranth Amanita muscaria

Beta vulgaris

betacyanins red, orange

betaxanthins yellow, orange

basic structure

N COOHH

N

H

HOOC

RR1

+

Page 14: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

betanin (R = H) vulgaxanthin I (R = NH2) vulgaxanthin II (R = H)

H

CH2OR

+

N COOH

N

H

HO COOH

HOOC

H

HO

OH

OH

OO

H

H

OR

N

N

H -+

COO

COOHHOOC

dominating betacyamin in beetroot (1-2 g/kg) use powder with 6-7% dyes beet (after fermentation, drying)

dyeing of dairy and meat products, soft drinks, sweets

Page 15: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

FLAVONOID PIGMENTS

fruits, vegetables, flowers anthocyanins red, violet, blue anthoxanthins yellow, orange

(anthos = flower, kyaneos = blue, xanthos = yellow) cca 5000 compounds

basic structure

2H-chromene flavan

OO

substituted by phenyl

Page 16: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

oxidation of 3C chain (ring B)

OH groups in rings A, B, C

aglycones, glycosides

colourless colourless- light yellow yellow light pale yellow red-blue

+

O

anthokyanidiny

flavonoly

O

O

flavony

O

O

OH

flavanonoly

O

O

flavanony

O

OH

OH

leukoanthokyanidiny

O

OH

katechiny

O

O

OH

Favan-3-ols catechins

Favan-3,4-diols leucoanthocyanidins

flavanonols flavavonols

flavanones flavones

anthocyanidines

Page 17: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Anthocyanins aglycones=anthocyanidins glycosides=anthocyanins

basic structure

+

O

OH

OH

OH

HO

R

R

1

2

35

7

pelargonidin Pg R1 = H R2 = H violet-red

cyanidin Cy R1 = H R2 = OH violet

delfinidin Dp R1 = OH R2 = OH blue-violet

peonidin Pn R1 = H R2 = OCH3 violet

petunidin Pt R1 = OH R2 = OCH3 dark red

malvidin Mv R1 = OCH3 R2 = OCH3 blue-violet

saccharides: Glc, Gal, Xyl, Ara, Rha,

always at C-3, often at C-3 and C-5, seldom at C-7

acids: p-cumaric, caffeic, ferulic

Page 18: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

anthocyanins fruits and vegetables

sophorose = -D-Glcp-(12)-D-Glcp

rutinose = -L-Rhap-(16)-D-Glcp

fruit anthocyanins sacharide, acid Blueberry Dp 3-rutinoside, 5-glucoside, 3-glucoside

(myrtillin) Grapes Cy, Pn, Dp, Pt,

Mv 3-p-kumaroyl, 3-kaffeoyl-3-glucosids

Strawberries Pg, Cy 3-glucoside Raspberries Cy, Pg 3-sophoroside, 3-rutinoside, 3-glucoside Blackberry Cy, Mv 3-glucoside, 3-rutinoside, free/acyls Black currant Cy, Dp 3-glucoside, 3,5-diglucoside, 3-rutinoside Cherries Cy, Pn 3-glucoside, 3-rutinoside vegetable anthocyanins sacharide, acid Onion Cy 3-glucoside, 3-galactoside (idaein) Eggplant Dp 3-glukoside, 3-rutinoside, 3,5-diglucoside Cabbage Cy malonyl (p-coumaroyl, di-p-coumaroyl,

feruloyl)-3-sophoroside-5-glucoside

Page 19: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

colour changes due to different factors

pH

co-pigmentation, eventual transformation into other pigments

SO2

H2O2

Page 20: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

pH

,2

1R

R

R1

R2

R1

R2

R1

R2

R1

R2

R1

R2

glykosyl

glykosylglykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

glykosyl

R1

R2

+

- H+

flavyliový kation (červený) karbinolová pseudobáze (bezb.)

H+

H+

neutrální chinoidní báze (tmavě červená)

chalkon (žlutá)H

+ H+

anion chinoidní báze (modrá)

--

- -

H2O

OH

O

HO O

O

OHOH

O

HO O

O

O

O

HO O

O

OH

O

O O

OOH

O

HO

O

OHO

O

O

-O O

O

O-

O

O O

O

H2O-

pH < 1 pH 4,0-4,5

pH 7,5-8

pH > 8

pH 4,5-7,5

glycosyl

glycosyl glycosyl

glycosyl

glycosyl

glycosyl glycosyl

glycosyl

glycosyl

glycosyl

glycosyl

glycosyl glycosyl

glycosyl

flavylium cation (red) carbinol pseudo base (colourless)

chalcone (yellow)

neutral quinoid bases (dark red)

quinoid base anions (blue)

Page 21: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

copigmentation

interaction with procyanidinins

(catechins = copigments) → coloured complexes

transformation into other pigments

coloured complexes → dimers (oligomers)

OR

OR

+

8

4

HO

OH

O

R

R

OH

OH

R

RHO

OH

O

anthokyanidin

katechincatechin

anthocyanin

Page 22: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

non-soluble condensation products, polymeric compounds flobafens

SO2 colourless sulfonic acids

H2O2 colourless products

HO2SO

OSO2H

OH

O

HO O

R

R

O

1

2

glykosyl

glykosyl

OH

O

O

R

R

O

1

2

glykosyl

glykosyl

O

HO OO

CO

O

R

R

OH

glykosyl

glykosyl

1

2

glycosyl

glycosyl glycosyl

glycosyl

glycosyl

glycosyl

Page 23: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Anthoxanthins flavanones pigments of low importance

bitter compounds of grapefruits

naringin = naringenin + neohesperidose

neohesperidin = hesperetin + neohesperidose

flavanonols pigments of low importance flavones important anthoxanthins

Page 24: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

flavonols important anthoxanthins antioxidant activity, rutin = kvercetin + rutinose, bioflavonoids Isoflavones pigments of low importance (e.g. in soybeans) estrogenic activity chalcones and aurones important pigments of flowers

(karthamin) dihydrochalcones pigments of low importance neohesperidindihydrochalcone (synthetic sweet compound)

Page 26: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

quinones benzoquinones naphtoquinones anthraquinones

benzo-1,4-quinone naphtho-1,4-quinone anthra-9,10-quinone

O

O

O

O

O

O

Page 27: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Benzoquinones arbutin (cranberry leaves, antiseptic activity)

O

CH2

OH

OH

HO

HO

OH

O

Naftoquinones juglone (leaves of walnut, 4-β-D-glucosid 1,4,5-trihydroxynaphtalene) (relative gossypol in cotton seeds, related coenzymes Q, vitamins K)

O

OOH

Page 28: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Anthraquinones related emodins, bianthrons carminic acid (cochineal, dried bodies of female beatles Coccus cacti)

hypericine (St. John's wort)

O OH

CH3

HO

CH3

OHO

HO

HO

HO

HO

OH

OH

CH2OH

O

OH

COOH

OH

CH3

HO

OH

O

O

E120 – meat and diary products, candy

Page 29: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

carotenoid pigments yellow, orange, red up to violet

pigments of plants and microorganisms (in mammals)

carotenoids (tetraterpenes, 40 C atoms, trans-isomers)

hydrocarbons carotenes

O-derivatives xanthophylls

neocarotenoids (cis-isomers)

degradated carotenoids (30, 20, 15, 13, 10 C atoms)

Page 30: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Carotenes acyclic and alicyclic hydrocarbons lycopene: tomato, rose-hip, β-carotene: carrot, apricot, mango

H3C

CH3 CH3 CH3 CH3

CH3 CH3 CH3

CH3

CH3lykopen

CH3

OH

H3C

H3C

CH3CH3

CH3CH3

CH3

CH3H3C

-karoten

lycopene

β-carotene

Page 31: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Xanthophylls alcohols, ketones, epoxides free, bound (glycosides, fatty acids esters, carotenoproteins)

CH3

OH

H3C

H3C

CH3CH3

CH3CH3

CH3

CH3

HO

H3C

CH3

OH

H3C

H3C

CH3CH3

CH3CH3

CH3

CH3

HO

H3C

zeaxanthin

lutein (-xanthofyl, kukurbitaxanthin) OH

H3C CH3

CH3O

CH3CH3

CH3CH3

CH3

CH3

HO

H3C

kapsanthin

O

OH

CH3H3C

H3C

O

HO

CH3H3C

CH3

CH3CH3

CH3CH3

astaxanthin

zeaxanthin, lutein: generally wide-spread kapsanthin: red bell pepper astaxanthin: fish, shellfish (α-crustacyanin)

Page 32: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Contenten (mg/kg)

Carotenoids Apricot Orange Carrots Spinach Tomato

Carotnes Lycopene 0.1 16-750 Neurosporene 3.0 -Carotene 0.4 0.5 8.4 Phytofluene 0.3 1.3 5.1 Phytoene 0.6 0.4 6.0 -Carotene 64 0.1-0.4 46-103 33-89 2.8-5.8 -Carotene 0.1-0.2 22-49 trace -Carotene 0.2 6.3-27 0.4-1.6 Xanthophylls 5,6-epoxylycopene 5.3 -Cryptoxanthin 0.1-7.1 Zeaxanthin 0.5 Lutein 0.3 1.1-5.6 42-81 0.4-1.3 Antheraxanthin 0.6 Violaxanthin 0.7 74 Neoxanthin 24 Mutatoxanthin 0.6 5.0 Luteoxanthin 1.7 Auroxanthin 1.2

Page 33: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

degradated carotenoids crocin (18 C)

saffron (Crocus sativus), spice

HOOCCOOH

CH3 CH3

CH3CH3krocetin

krocinOH

H

O

O

H

OH

O

OH

OH

CH2

O

O

OH

CH2

O

CH2

O

OH

O OH

HOO

CH3CH3

CH3CH3

CC

O

O

O OH

OH

HOCH2OH

genciobiosa

•1 kilogram of dried saffron is roughly 150 000 and 200 000 flowers →high price • odor is sharp and pungent, tastes warm, earthy, musky

crocetin

crocin

gentiobiose

Page 34: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

annato (20 C)

bixin (Bixa orellana)

extract 0,2-0,5% = mixture cis/trans-isomers,

cheese and margarine colouring

9

,HOOCCH3

CH3 CH3

CH3

COOH

HOOC

CH3 CH3

CH3CH3

COOH

Annatto is commonly

used in Latin American

and Caribbean cuisines

as both a coloring and

flavoring agent.

Page 35: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

reactions

hydrolysis of esters, glycosides

dehydration of alcohols to hydrocarbons

cis/trans isomeration

(neocarotenoids, low colour intensity)

autoxidation

(low colour intensity, even decolourisation)

antioxidants

consequences • flour bleaching • colour changes of orange juices • food flavour • beneficial food components

Page 36: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

ENZYMATIC BROWNING REACTIONS substrates

phenols, diphenols (polyphenols), esters (depsides), glycosides

HO R HO

HO

R

Food Substrate Potatoes Tyr, chlorogenic acid, catechins Apple flesh chlorogenic acid Apple skin flavonoids (catechins) Pears chlorogenic acid (caffeic + quinic) Olives 3,4-dihydroxyphenylethanol and its derivatives Bananasy 3,4-dihydroxyphenylethylamie Dates dactyliferic (caffeic + shikimic) acid Beans DOPA Mushrooms Tyr, terfenylchinons Tea flavonoids (catechins) Coffee chlorogenic and caffeic acid Cocoa flavonoids (catechins)

Page 37: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

OH

HO

daktyliferová kyselinachlorogenová kyselina

3

COOH

OH

OH

O

O

OH

OH

3

COOH

OH

OH

OH

O

O

OH

OH

O

O

O H

HOR

R

terfenylchinony

HO

HO

NH2

3,4-dihydroxyfenylethylamin

chlorogenic acid dactyliferic acid

3,4-dihydroxyphenylethylamie terphenylquinones

Page 38: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

enzymes

Polyphenoloxidases

catecholoxidase

1/2 O2 1/2 O2

OH

R

OH

R

OH

O

O

R

H2O-

fenol o-difenol o-chinon

kresolasa katecholasa

phenol o-diphenol o-quinone

cresolase catecholase

Page 39: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

laccase

catechin oxidation yellow quinone

chlorogenic acid oxidation yellow-orange quinone

DOPA oxidation orange quinone

OH

HO

R

H2O-

R

O

O

OH

R

OH

O

O

R

H2O-

o-difenol o-chinon

p-difenol p-chinon

lakkasa

lakkasa

1/2 O2

1/2 O2

laccase

laccase

o-diphenol

p-diphenol

o-quinone

p-quinone

Page 40: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

Non-enzymatic oxidation

inhibition of browning (book 3, tab. 9.16)

inhibition of enzymes (oxygen elimination , decrease of pH)

chelatation of metals (Cu2+)

use of reducing compounds (ascorbic acid, SO2)

desirable reactions

tee fermentation

cocoa fermentation

olive fermentation

oxidace

hnědé

pigmenty

OH

R

OH

O

O

R

+

OH

OH

R

R

HO

OH

R

HO

OH

O

O

R1/2 O2

- H2O

reakce s R-SH, R-NH2

oxidace

polymerace

komplexy s kovy

oxidation

reaciton with R-SH, R-NH2

oxidation

polymerization

metal complexes

brown

pigments

Page 41: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

black tea

precursors in green tea

epigallocatechingallates

epicatechins

epicatechingallates

epigallocatechins

main types of black tea pigments

theaflavins (oxidised flavonoid dimers),

orange-red (seven-carbon tropolone cycles)

Page 42: Pigments and other colorants - vscht.cz Pigments and... · Pigments and other colorants Colou red compounds (colorants, pigments) colour effect based on the selective absorption of

thearubigines (polymers, 700-400 000 Da),

red-yellow up to orange-brown

1

OHO

OH

H

H

OH

OHOR

OR

HO

OH

O

H

HO

OH