The multiple role of polyphenol chemistry in coffee associated … · 2014-11-23 · The multiple...

The multiple role of polyphenol chemistry

in coffee associated with quality attributes

24th ASIC Conference, Costa Rica, 13.11.2012 Arne Glabasnia, Imre Blank, Federico Mora, Valérie Leloup, Josef Kerler

Nestlé PTC Orbe

AGENDA

• Introduction

• Coffee polyphenols as quality markers for green coffee

• Coffee Polyphenols and aroma

• Coffee Polyphenols and taste

• Coffee Polyphenols and health

• Conclusion

PTC Orbe-Science&Nutrition / AGL / 13.11.2012

(Poly)phenols

Flavanols

Isoflavones (genistein,

daidzein)

Flavonols (e.g. quercetin)

Anthocyanins

Catechins Pro(antho)cyanidins

Flavanones

e.g. hesperidin

Flavonoids

Phenolic acids (e.g ferulic

acid, caffeic acid,

chlorogenic acids)

Ellagic acid/ellagitannins

The family tree of (poly)phenols

Antioxidants

Others (BHT, Vit C)


Chlorogenic acids are the major phenols in coffee


Quinic acid Intermediate from the shikimic acid cycle

Chlorogenic acids Esters of quinic acid with hydroxycinnamic acids

Cinnamic acids Common metabolites in plants

OH

OH

OH

OH

O

OH

R

OH

O

OH

OH

OH

OH

O

O

OH

RO

OH

O

OH

OH

O

OH

R

O

OH

OH

O

OH

O

OH

R

O

O

OH

OH

OH

O

OH O

R

Diversity of chlorogenic acids in coffee


3-caffeoyl quinic acid 4-caffeoyl quinic acid 5-caffeoyl quinic acid

coumaric acid dimethoxycaffeic acid trimethoxycaffeic acid sinapic acid

RO

O

OH

RO

O

OH

OCH3

OCH3

RO

O

OCH3

OCH3

OCH3

RO

O

OCH3

OCH3

OH

O

OH

OH

O

OH

O

OH

OH

OH

OH

OH

O

O

OH

O

OH

OH

OH

OH

O

OH

O

OH O OH

OH

3-feruoyl quinic acid 4-feruoyl quinic acid 5-feruoyl quinic acid

OH

O

OH

OH

O

OH

O

OH

H3CO

OH

OH

OH

O

O

OH

O

OH

OCH3

OH

OH

O

OH

O

OH O OH

OCH3

Diversity further increased by presence of diesters


Di-Caffeoylquinic acids

1C,3CQA

1C,4CQA

1C,5CQA

1F,3FQA

1F,4FQA

1F,5FQA

3F,4FQA

3F,5FQA

4F,5FQA

1C,3FQA

1C,4FQA

1C,5FQA

3C,4FQA

3C,5FQA

4C,5FQA

1F,3CQA

1F,4CQA

1F,5CQA

3F,4CQA

3F,5CQA

4F,5CQA

+ all homo- and heterodiesters containing

- coumaric acid

- dimethoxycaffeic acid

- trimethoxycaffeic acid

- sinapic acid

More than 100 different Di-Chlorogenic acid

3,4-dicaffeoyl quinic acid 3,5-dicaffeoyl quinic acid 4,5-dicaffeoyl quinic acid

OH

O

O

OH

O

OH O OH

OH

O

OH

OH

OH

O

OH

O

O

OH

O

OHOH

O

OH OH

OH

OH

O

O

O

OH

O

OH

OH

O

OH

OH

Coffee phenols as quality

markers for green coffee


Chlorogenic acids as quality markers for blend

• To differentiate between Robusta and Arabica

• To calculate blend of unknown samples

– LC-DAD (Mullen et al. 2011)

– by NIR (Haiduc et al.)

– by NMR (Wei et al. 2010)

– by LC/MS direct infusion (Garrett et al. 2012)


Arabica

Robusta

Haiduc et al, unpublished Garrett et al, 2012

Chlorogenic acids as markers for coffee origin

• CGA used in as indicator of origin (Alonso-Salces et al, 2009)

- to classify Robusta coffees from Cameroon, Indonesia, Vietnam

- to classify Arabicas from America and Africa

• No effect for origin for Robusta from Africa (Ky et al 2001)


Robusta Arabica

Alonso-Salces, 2009 Alonso-Salces, 2009

Differentiation of cultivar by CGA content


Monteiro et al (2012)

• Differentiation of cultivars by CGA profile sometimes possible

• Crop to crop variety for one cultivar bigger than from cultivar to cultivar

Chlorogenic acids as quality markers for post-harvest

treatment

• 17 brazilians cultivars analysed for CGAs, trigonelline, caffeine and sucrose

• In average higher CGA content in wet-processed coffee compared to semi-dry

• Trigonelline higher as well, sucrose lower, no effect on caffeine


0

1000

2000

3000

4000

5000

6000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

5-C

QA

[m

g/1

00g

]

semi-dry wet

(adapted from Duarte et al, 2010)

Chlorogenic acids in correlation with cup quality

• Correlation of CGA content with cup quality (Farah et al, 2006)

• The higher the CGA content the lower the cup quality


Cup quality

Farah et al (2006)

Coffee phenols and their role in

coffee aroma



Chlorogenic acids as aroma precursors upon roasting

Important aroma compounds in roasted coffee


Semmelroch et al. (1995)

CH2

OH

OCH3

O

OH

OCH3

CH3

OH

OCH3

OH

OCH3

4-vinylguaiacol

guaiacol

4-ethylguaiacol

vanillin

Phenolic impact compounds Compound Arabica Robusta

(E)-beta-damescenone 260000 270000

furfurylthiol 110000 170000

MMBF 37000 33000

MBT 27300 27700

3-isobutyl-2-methoxypyrazin 16600 2400

homofuraneol 15000 12000

furaneol 11000 5700

2,3-butandione 3390 3190

4-vinylguaiacol 3200 8900

guaiacol 1700 11000

2,3-pentandione 1320 660

methional 1200 500

vanillin 192 644

2-ethyl-3,5-dimethylpyrazin 165 470

2,3-diethyl-5-methylpyrazin 95 310

sotolon 74 32

4-ethylguaiacol 32 362

abhexon 21 11

Dose-over threshold


0

20

40

60

80

100

0 10 20

Rela

tiv

e h

ead

sp

ace c

on

cen

trati

on

(%

)

DMS

Ethanethiol

FFT

MMBF

N-Methylpyrrole

2,3-Pentanedione

Significant losses in headspace concentration

of e.g. thiols, pyrroles occur within hours

Time (hours)

Role of chlorogenic acids in aroma staling

Mueller et al, 2007

Losses in headspace concentration

of FFT occur within minutes

Are chlorogenic acids involved in that degradation?

hydroxyhydroquinone

(HHQ)

(Müller et al, 2007)

Trapping of key odorants (thiols) by polyphenols via

oxidative coupling


The loss of 2-furfurylthiol during coffee storage is mainly due to the oxidative coupling

of the odorant to hydroxyhydroquinone (2), giving rise to the conjugates 9 and 10.

Reaction possible for intact CGAs but not found in coffee


catechol adduct

caffeic acid adduct

CQA adduct

Formed in model experiments Found in coffee brew

OH

OH

S

OOH

S

OOH

OH

S

OOH

OH

CH3

OH

OH

S

OOH

O

(Mueller et al, 2007)

S

Chlorogenic acids involved in coffee staling but not

exclusively


?

OSH

OSH

R

OS

radical inducedoxidation (C-radical)

RS

oxidation - director radical induced(S-radical)

N

N SO

SO

R

R

R

N

N

RR

N

N

R

nucleophilicaddition at melanoidins

OH

OH

S

O

SO

OH

OH

O

Onucleophilicaddition at chlorogenic acid

derivatives

+ .

+

+

reaction with aldehydes/

heterocycles

N

S

O

Hofmann &

Schieberle

(2002)

Müller &

Hofmann

(2005)

Munro et al.

(2003)

Milo et al.

(unpublished )

Coffee phenols and their role in

coffee taste


CGAs as precursors for tastants: lactones

• Lactone formation well known (Farah et al, 2005)

• Lactones have been identified as bitter compounds in coffee (Frank et al.

2006) giving pleasant coffee-like bitter taste


Frank et al., 2006

Frank et al., 2006

Compound mg/l umol/l

3-O-caffeoyl-γ-quinide (2a) 13.4 40

4-O-caffeoyl-γ- quinide (3a) 12.1 36

5-O-caffeoyl-epi-δ-qunide (4a) 60.5 180

4-O-caffeoyl-muco-γ- quinide (5a) 11.2 30

5-O-caffeoyl-muco-γ- quinide (6a) 9.7 29

3-O-feruoyl-γ-quinide (2b) 13.7 39

4-O-feruoyl-γ- quinide (3b) 13.7 39

3,4-O-dicaffeoyl-γ-quinide 4.8 9.8

3,5-O-dicaffeoyl-epi-δ-quinide 24.9 50

4,5-O-dicaffeoyl-muco-γ- quinide (3a) 4.8 9.8

Bitter threshold

CGAs as precursors for tastants: phenylindanes

• Phenylindanes another class of bitter compounds formed from CQA degradation


HO OH

O

O

OH

OHOH

HOOC

HO OH

O

OH

HO COOH

HO

OH

HO OH

HO OH

H+

H

OH

OH

R1 OH

H3C

OH

OH

R1

HO

OH

OH

R1

HO

H

OHHO

R1 OH

H3C

HO OH

Interm.

H

OH

OH

R1 OH

H3C

HO

HO

5-Chlorogenic acid caffeic acid

quinic acid

4-vinyl catechol

phenylindanes

phenylbutanes

phenylbutenes

diphenylindanes

5-CQA caffeic acid vinylcatechol

phenylbutanes

phenylbutenes

phenylindanes

diphenylindanes

Compound mg/l µmol/l

Phenylbutanes 6 23

Phenylbutenes 39 145

Phenylindanes 9-40 32-148

Diphenylindanes 15-27 37-67

Bitter threshold

Frank et al., 2007 Frank et al., 2007

CGA as precursors for tastants: furan benzene diols

• Benzene diols are formed from catechols and furan derivatives in

model roast experiments (Kreppenhofer et al. 2010)


O

OH

O+

CH2

OCH2

+

H+

- H20

OH

OH

O

OH

O

OH O OH

OH OH

OH

R O

O

R

O

OH

OH

furfuryl alcohol

catechol 4-CQA

4-(furan-2-ylmethyl)benzene-1,2-diol

O

OH

OH

O

OH

OH

OH

O

OH

OH

CH3

O

OH CH3

OH

TC: 9.6 mg/L TC: 6.5 mg/L

TC: 5.7 mg/L TC: 7.5 mg/L

+

Kreppenhofer et al, 2007

Formation of bitter tastants upon roasting


0

20

40

60

80

100

120

green 110 90 70 50

Rel%

Roast degree

Roasting

Caffeine CQL DKP Phenylindane • Bitter precursor content

depends on blend

• Bitter compound formation

depends on roasting degree

• Kinetics are different for

different chemical classes

• Bitter quality also different

coffee-like

harsh

caffeine-like

metallic

Compound class Threshold for bitterness (umol/L)

Caffeine 750

Lactones 30-200

DKPs 190-4000

Phenylindanes 30-150

Benzenediols 100-800

Sensory analytical correlation

Profiling was carried out with an expert panel (n=12)

The basic

attributes...

• roasty

• bitter

• acid

The ‚subtle‘ aroma descriptors...

fruity-floral

red fruits, lemon, jasmine

green-vegetal

herbs, fresh vegetables

dry-vegetal

wood, malt, cereal

vegetal-humus

earthy, mushroom

cacao

roasted, cacao, dark chocolate

sweet

vanilla, caramel, honey

... describe the basic

properties of an

Espresso coffee

... describe the signature

aroma of an Espresso coffee

... are grouped based on

olfactive similarity

Baggenstoss et al, ASIC 2010


54 aroma and taste compounds were analyzed for the

present study

substance flavor quality substance flavor quality

1 methanethiol sulfur, garlic 28 2-acetylthiazole roasty, popcorn

2 dimethyl sulfide cabbage, sulfur 29 furfural grass, almond 3 dimethyl trisulfide sulfur, cabbage 30 furfuryl acetate -

4 furfurylthiol sulfur, roast 31 2,3,5-trimethylpyrazine roasty

5 3-mercapto-3-methylbutylformate catty 32 2-ethyl-3,6-dimethylpyrazine roasty, earthy 6 methional potato 33 2-ethyl-3,5-dimethylpyrazine roasty, earthy

7 3-methyl-2-butenethiol sulfur, amine 34 2-ethenyl-3,5-dimethylpyrazine roasty, earthy 8 2-methyl-3-furanthiol meat 35 2,3-diethyl-5-methylpyrazine roasty, earthy 9 acetaldehyde pungent, fruity 36 2-acetylpyrazine roasty

10 propanal solvent, pungent, fruity 37 2-isopropyl-3-methoxypyrazine pea, earthy 11 2-methylpropanal fruity, pungent 38 2-isobutyl-3-methoxypyrazine pea, earthy 12 2-methylbutanal fruity, cocoa 39 β-damascenone rose, honey 13 3-methylbutanal malty 40 sotolon maggi, curry 14 phenylacetaldehyde honey 41 furaneol caramel 15 hexanal grass 42 maltol caramel 16 2,3-butanedione buttery 43 3-CQA - 17 2,3-pentanedione buttery 44 5-CQA -

18 vanilline vanilla 45 4-CQA - 19 ethyl 2-methylbutanoate fruity 46 5-CQL bitter 20 ethyl 3-methylbutanoate fruity 47 4-CQL bitter

21 p-cresol medicinal, phenolic, smoke 48 5-FQA - 22 guaiacol smoke, medicine 49 4-FQA -

23 4-ethylguaiacol spice, clove 50 cyclo-Val-Pro bitter

24 4-vinylguaiacol spice, clove 51 cyclo-Ala-Pro bitter 25 N-methylpyrrole - 52 cyclo-Pro-Leu bitter

26 pyridine - 53 cyclo-Phe-Pro bitter

27 2-acetylpyridine popcorn 54 caffeine bitter



Around 30 compounds exhibit strong correlation to

aroma quality


-1.0 -0.5 0.0 0.5 1.0

-1.0

-0

.5

0.0

0

.5

1.0

Comp1

Com

p2

R1

E1

E5

L1 L2

R2

R3

E4

E2

E6

L3

E3

CTn

dimethyl trisulfide

2,3-pentanedione

N-methylpyrrole

2-acetylpyridine

guaiacol

furaneol

methanethiol

dimethyl sulfide

furfurylthiol acetaldehyde

2-methylpropanal

2-methylbutanal

phenylacetaldehyde

hexanal

2,3-butanedione

pyridine

2-acetylthiazole

furfural

furfuryl acetate

2,3,5-trimethylpyrazine

2,3-diethyl-5-methylpyrazine

2-isopropyl-3-

methoxypyrazine

2-isobutyl-3-methoxypyrazine

p-cresol

4-ethylguaiacol 4-vinylguaiacol

3-methyl-2-

butene-1-thiol

2-methyl-3-furanthiol methional

sotolon

vanilline

25mL (Ristretto) 40mL (Espresso)

110mL (Lungo)

green-vegetal

vegetal-humus

cocoa fruity-flowery

sweet

roasty

bitter acid

dry-vegetal

No correlation with lactones

found for bitterness perception


Around 30 compounds exhibit strong correlation to the

sensory descriptors

sweet

roasty

dry vegetal

cocoa

bitter

vegetal-humus

green vegetal

acid

fruity-flowery

2-acetylpyridine

pyridine furfuryl acetate

phenylacetaldehyde

3-methyl-2-butene-

thiol

N-methylpyrrole

2-isopropyl-3-methoxypyrazine

2-methyl-3-furanthiol

4-ethylguaiacol

guaiacol

4-vinylguaiacol

dimethyl trisulfide

2,3-diethyl-5-methylpyrazine p-cresol

2-isobutyl-3-methoxypyrazine

2-methylpropanal

vanilline

2-acetylthiazole

hexanal

2-methylbutanal

methional

furfural

sotolon

furaneol

2,3-pentanedione

dimethyl sulfide

2,3,5-trimethylpyrazine

2-furfurylthiol

acetaldehyde

methanethiol

2,3-butanedione

Correlation found for aroma

compounds derived from CQA

breakdown with bitterness

perception



Bitterness prediction model from aroma compounds

including those derived from CQA is very good



Coffee phenols and their role for

health


Polyphenols/flavonoids have been considered to

have an effect on health for many years

1936

1957

Albert von Szent-

Györgyi Nobel Prize in

Physiology or Medicine

(1937)


The importance of coffee polyphenols in human diet

Coffee

• 36. place in mg/100g

• 6. place per serving

• 1. place for daily consumption

(3-4 cups per day)


0 40 80 120 160

dark chocolate

blackberry

highbush blueberry

plum

cider apple

orange juice

green tea infusion

strawberry

grapefruit

raspberry

peach

broad bean

dessert apple

red wine

nectarine

black grape

pecan

apricot

black tea

pearepicatechincatechinprocyanidin B2procyanidin B3procyanidin B1procyanidin C1procyanidin EECEGCEGCGcyanidindelphinidinmalvidinpelargonidinpetunidinquercetinhesperidinnaringenin

(mg/100g fresh weight)

Scalbert et al, 2010

CQAs most contributors to polyphenol intake in French

adults

Scalbert et al, 2011


More and more reports on positive effects on health for a

moderate coffee consumption

• Robust inverse relation between regular coffee consumption, including

decaffeinated, and risk of type 2 diabetes based on meta-analyses of

epidemiological studies (van Dam 2006; van Dam and Hu 2005)

• Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2

diabetes mellitus: a systematic review with meta-analysis. (Huxley et al 2009)

• The use of green coffee extract as a weight loss supplement: a systematic

review and meta-analysis of randomised clinical trials. (Onakpoya et al 2011)

• Lipophilic antioxidants more neuroprotective than hydrophilic (e.g. lactones

(Chu et al 2009)

• High CQA coffees prevent oxidative damage (Hoelzl et al 2010)

• Antioxidant rich coffee reduces DNA damage (Bakuradze et al, 2011)

• CGA rich coffee induce chemopreventive phase II enzymes (Boettler et al.

2011)

• Coffee has positive effects to reduce cognitive decline (Abreu et al, 2011)

• ASIC session yesterday


Antioxidant activity of green coffee comes mainly from

CGAs

• More than 100 coffee polyphenols have been already reported in the

literature by the scientific community (Clifford & Kuhnert )

Total Antioxidant Activity

by folin in%

CQA FQA di-CQA

• 80% of the total antioxidant activity in green coffee comes from the 9

main chlorogenic acid

OH

OH

OH

O

O

OH

O

OH

OH

OH

OH

OH

O

O

OH

O

OH

OCH3

OH

O

O

OH

O

OH O OH

OH

O

OH

OH



0

50

100

150

200

250

300

350

400

GC Light Medium DarkT

ota

l po

lyp

hen

ols

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

0

50

100

150

200

250

300

350

400

GC Light Medium Dark

An

tio

xid

ant

cap

acit

y

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

0

50

100

150

200

250

300

350

400


An

tio

xid

ant

cap

acit

y

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

0

100

200

300

400

500

600


An

tio

xid

ant

cap

acit

y

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

0

50

100

150

200

250

300

350

400


To

tal p

oly

ph

eno

ls

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

0

100

200

300

400

500

600


To

tal p

oly

ph

eno

ls

(µm

ol 3

CQ

A /g

gre

en c

offe

e d.

b.)

From 9 CGAs

From melanoidins

a)Total polyphenols by FOLIN

b) Antioxidant capacity by ABTS

Antioxidant activity in roasted coffee stays at high level but

is less explained by CGAs

Leloup et al, ASIC 2010

-150

-100

-50

0

50

100

150

0 10 20 30 40 50 60 70 80

retention time (min)

Abso

rptio

n

5mg/mL 325nm

ABTS


-200

-100

0

100

200

300

400

500

0 10 20 30 40 50 60 70 80

retention time (min)

Abso

rptio

n 5mg/mL

325nm

ABTS

CQAs diCQAs

FQAs

Antioxidant activity of roasted coffee derives from small

new peaks but mainly from a unresolved hump



▼

＊

＊

＊

● ●

●

▼

▼

＊

CQA

Lactones

di-CQA

Caffeic acid moiety

＊

CafTrp

Inte

ns

ity

Retention time (min)

5 10 15 20 25 30 35 40 45 50

▼

＊

＊

＊

● ●

●

▼

▼

＊

CQA

Lactones

di-CQA

Caffeic acid moiety

＊

CafTrp▼

＊

＊

＊

● ●

●

▼

▼

＊

CQA

Lactones

di-CQA

Caffeic acid moiety

＊

CafTrp▼

＊

＊

＊

● ●

●

▼

▼

＊

CQA

Lactones

di-CQA

Caffeic acid moiety

＊

CafTrp

Inte

ns

ity

Retention time (min)

5 10 15 20 25 30 35 40 45 50

Precursor ion scan by LC/MS of a roasted coffee to detect

precursors of caffeic acid moiety


Caffeic acid moiety largely present in unresolved hump


Incorporation of chlorogenic acids into coffee melanoidins

Bekedam et al, 2007

Model roasting of 5-CQA at 200°C in dry state

0

20

40

60

80

100

120

0 10 20 30

g/1

00g

heating time in minutes

CQA content Folin response

RT: 0.08 - 38.21

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

Time (min)

-5000

0

5000

10000

15000

20000

-5000

0

5000

10000

15000

20000

-5000

0

5000

10000

15000

20000

uA

U

-5000

0

5000

10000

15000

20000

RT: 4.22

AA: 756821.2310.391.46 14.37

5.30

4.0914.2311.02

12.173.62 15.17

4.76

3.17 15.9011.11 14.763.36 16.48 28.7517.452.62 6.38 12.68

RT: 15.98

MA: 905098

17.554.74

3.13 11.15 14.75

28.8928.4724.766.372.53 12.81

NL:

2.37E4

Channel B

UV

Genesis

NHW_1112

08_02_111

208161859

NL:

2.37E4

Channel B

UV

nhw_11120

8_04

NL:

2.37E4

Channel B

UV

nhw_11120

8_06

NL:

2.37E4

Channel B

UV

nhw_11120

8_08lactones

HPLC chromatogram from final reaction mixture Degradation of 5-CQA and Folin of reaction mixture

• 5-CQA is rapidly degraded in model roast mix at 200°C

• TPP by Folin of reaction mixture remains almost constant

• Lactones are formed but cannot explain loss of 5-CQA and Folin values

• A lot of minor peaks are detectable

• Chromatographic tools suitable?


C:\Xcalibur\data\Kaffee\111208c 09.12.2011 17:05:03 CQA + Sucrose 30 min

111208c #10 RT: 0.27 AV: 1 NL: 4.23E7

T: - c ESI Full ms [ 150.00-2000.00]

200 400 600 800 1000 1200 1400 1600 1800 2000

m/z

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Re

lativ

e A

bu

nd

an

ce

689.12

1025.15671.08 707.18

191.12

851.15

515.10

1007.11

1361.14

352.93

863.15 1187.20833.09497.07

255.191169.15

1343.17

1697.081523.141043.16

1679.25995.17 1859.27651.15471.10 807.06 1143.12881.11 1223.29 1996.90561.06 1736.08

Direct infusion into LC/MS of model roast of 5-CQA

Polymerization of CQA can be observed

CQA

CQL

DiCQA

Di-CQL

+174

QA-H2O

+162

CA-H2O

+174

QA-H2O +162

CA-H2O

OH

OH

OH

OH

O

OH

OH

OH

O

O

O

OH

OH

OOH

O

O

OHO

O

OH

OH

OH

OH

O

OH

OH

OH

O

O

O

OH

O

OOH

O

O

OHO

OH

OH

O

O

OH

OH

O

OH

OH

OH

OH

O

O

OH

OH

OOH

O

O

OHO

+174

QA-H2O

OH

OH

OH

OH

O

O

OOH

OH

O

OH

O


OH

OH

OH

OOH

OH

O

OHO

polymers

Possible transformations of CGA and the effect on AOX

properties

OH

OH

OH

OOH

OH

O

OHO

Chlorogenic acid

AOX property

Polymerization

OH

OH

OH

OH

O

OH

OH

OH

O

O

O

OH

O

OOH

O

O

OHO

OH

OH

O

O

OH

OH

OH

OH

O

OH

OH

OH

O

O

O

OH

OH

OOH

O

O

OHO

O

OH

OH OH

O

O

OHO

OH

OH

OH

OH

OOH

OH

O

OHO

OH

OH

O

OOH

OH

O

OO


x 2

OH

OH

O

OH

CH2

OH

OH

OH

OH

OH

OH

OH

OH

CH3

S

O

OH

OH

Nucl.

Conclusions

• Chlorogenic acids can be used to evaluate green coffee quality

with regards to variety, origin and post-harvest treatment

• Chlorogenic acids play a crucial role in the formation and

degradation of important coffee aroma compounds

• Chlorogenic acids are the main precursors of several bitter

compounds in coffee

• Chlorogenic acids are converted into various compounds upon

thermal treatment whilst maintaining the antioxidant activity


…Coffee is the

most pleasurable

hot beverage in

the world

But one thing is sure...


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