[doi 10.1007%2f978!1!4615-4783-9_7] shahidi, fereidoon; ho, chi-tang -- flavor chemistry of ethnic...

8/8/2019 [Doi 10.1007%2F978!1!4615-4783-9_7] Shahidi, Fereidoon; Ho, Chi-Tang -- Flavor Chemistry of Ethnic Foods Chara…

1/8

CHARACTER IMPACT AROMA COMPONENTS

OF CORIANDER

CORIANDRUMSATIVUML.

HERB

K. R. Cadwallader, R. Surakarnkul, S.-P. Yang, and T.

E.

Webb

Department

o

Food Science and Technology

Mississippi Agricultural and Forestry Experiment Station

Mississippi State University

Box 9805, Mississippi State, Mississippi 39762

Volatile components were isolated from freshly harvested and market samples

o

coriander

herb cilantro) by direct solvent extraction with dichloromethane and analyzed by gas ~ r o m -

tography GC)-mass spectrometry, GC-olfactometry, and aroma extract dilution analysis

AEDA). Enzyme decompositon

o

volatiles was minimized by conducting extractions at re

duced temperature and in the presence

o

saturated sodium chloride. Volatile components

o

both samples were composed mainly

o

E)-2-alkenals and alkanals, with E)-2-decenal and

E)-2-dodecenal, and E)-2-tetradecenal being the most abundant compounds. Results o

AEDA revealed that Z)-3-Hexenal green/cut-grass) and an unknown odorant ran

cid/sour/old cut-grass) had the greatest impact on the aroma o fresh-picked cilantro; however,

in the market sample Z)-3-hexenal was not detected and the unknown was at low odor inten

sity. E)-2-Alkenals from C9-C14 and dec anal were predominant odorants in both samples.

These odorant provided mainly green/cut-grass and fatty/waxy aroma notes. Three unknown

odorants, having fresh/swimming pool-like notes, were also found a high intensity in both

samples.

INTRODUCTION

7

Coriandrum sativum L., a member o the Umbelliferae family, is cultivated world

wide to produce both coriander spice fruit) and fresh leaves herb). Coriander herb, more

commonly referred to as cilantro or Chinese parsley, is an important culinary herb and an

ingredient

o

many ethnic foods. A considerable amount o research has been conducted

on the essential oil o coriander spice; however, comparatively few studies have focused

on the volatile constituents o coriander herb.

Carlblom 1936) performed the first study on coriander herb composition and re

ported aldehydes ( ,,95%) as the major volatile components. Decanal was the most abun-

Flavor Chemistry o Ethnic Foods edited by Shahidi and Ho

Kluwer Academic / Plenum Publishers, New

York,

1999.


2/8

78

K. R. Cadwallader

t

a

dant aldehyde, with 2-decenal and 8-methyl-2-nonenal also being identified. Later studies

confirmed the presence of these compounds in coriander herb. Although these reports dif

fer from one another with respect to the relative abundances of these compounds, most

agree in that a series of saturated aldehydes and 2-alkenals are the major volatiles. Scratz

and Qadry 1966) reported 2-tridecenal and dec anal to be the predominant leaf volatiles

during the early stages of coriander development. MacLeod and Islam 1976) and Potter

and Fagerson 1990) employed simultaneous steam distillation-solvent extraction SDE)

for the isolation of the herb oil constituents. Both studies found alkanals and alkenals to be

the major constituents, but differed markedly in the actual composition reported. MacLeod

and Islam 1976) found 7-dodecenal

( ~ 2 1 ) as

the major component and did not detect

any 2-alkenals; however, 7-dodecenal was not identified by Potter and Fagerson 1990)

who reported E)-2-decenal ( ~ 4 6 )

as

predominant. Elsewhere, Lawrence 1986) reported

alkanals and 2-alkenals as major constituents of coriander plants during ontogenesis. Simi

lar results were reported by Mookherjee

t af

1989). Smallfield

t af

1993) studied the

effects

of

postharvest treatment on the composition

of

coriander herb oil isolated by steam

distillation and solvent extraction. Alkanals and alkenals were identified, with E)-2-dece

nal being the major volatile constituent. The relative levels

of

aldehydes were found to de

crease during storage of chopped herb, while levels of alcohols increased. Recently, Potter

1996) reported coriander leaf oil

to

contain mainly aldehydes C

IO

-C

I6

) with E)-2-

alkenals predominanting. Considerable quantitative differences were observed between

two commercial samples that were examined, as well as during ontogenesis for plants

propagated in growth chambers.

The above review demonstrates the considerable confusion that exists over the vola

tile composition of coriander herb. While it is clear that alkanals and 2-alkenals are major

constituents, the role of these compounds in the aroma of coriander herb has not been ad

dressed. Furthermore, previous researchers relied mainly on distillation methods for isola

tion of volatiles, but such techniques could lead to artifact formation or loss of thermally

labile constituents. The objectives of the present study were I) to develop a solvent extrac

tion technique to isolate the volatile components of coriander herb with minimal composi

tional changes and 2) to identify potent odor-active components in the extracts by aroma

extract dilution analysis and GC-MS.

M TERI LS ND METHODS

Materials

Coriander plants hereafter referred to as cilantro) were obtained from two sources.

Sample A was cultivated locally Starkville, MS) by a commercial produce and herb

grower. Sample B was obtained from a local grocery store and originated from California.

Both varieties are unknown. In the case of sample A, plants were harvested by uprooting

and extracting within 1

h.

For sample

B,

extraction was within 1 h of purchase.

Reference standards listed in Table I were obtained from the following commercial

sources: nos. 2, 3, 5,

7,

12,

13, 16,

18 20 22 and 24 Adrich Chemical Co., St. Louis,

MO); nos.

6, 9,

and II

AI fa,

Ward Hill, MA); nos. I and 26 Bedokian Research Inc.,

Danbury, CT); and no. 10 Polyscience, Niles, IL). 3-Heptanol internal standard), metha

nol, and sodium chloride were purchased from Aldrich Chemical Co. Dichloromethane

Aldrich Chemical Co.) was redistilled prior

to

use.


3/8

Character -Impact Aroma Components of Coriander

79

Isolation

o

Volatiles

Fresh leaves

lOg)

were cut from plants with stainless steel scissors. Leaves plus

10

ilL

of

an internal standard solution (3-heptanol, 3.07 Ilg/IlL in methanol) and

109 of

so

dium chloride were transferred to a 250-mL glass centrifuge bottle. The bottle was im

mersed in liquid nitrogen and the frozen contents ground into a fine powder with a pestle.

After warming the ground herb

to O°C

in an ice-water bath, ice-cold dichloromethane

(50 mL) was added and the contents blended using a hand-held mixer (Bio Homogenizer,

Biospec Products, Inc., Bartlesville, OK). The mixture was filtered through no. 40 filter

paper (Whatman) and the filtrate was stored at -20°C in order to freeze-out excess water.

Extract was concentrated to

10

mL under a gentle stream of nitrogen, dried by passage

through 2 g of anhydrous sodium sulfate and then stored at -20°C prior to analysis. Three

extracts were prepared for each sample.

Gas Chromatography-Mass Spectrometry GC-MS)

GC-MS system consisted of an HP 5890 Series II GC/HP 5972 mass selective detec

tor (MSD, Hewlett-Packard, Co., Palo Alto, CA). Separations were performed on fused sil

ica capillary columns (DB-WAX or DB-5ms, 60 m length x 0.25 mm i.d. x 0.25 lm film

thickness (d

r

); J W Scientific, Folson, CA). Extracts 3 )lL) were injected in the splitless

mode (200°C injector temperature; 30 s valve-delay). The carrier gas was helium at a linear

velocity of 25 cmls (at 40°C). Oven temperature was programmed from 40°C to 200°C at a

rate of 3°C/min with initial and final hold times

of

5 and 60 min, respectively. MSD condi

tions were as follows: capillary direct interface temperature, 280C; ionization energy, 70

eV; mass range, 33-350 a.m.u.; EM voltage (Atune 200 V); scan rate, 2.2 scans/so

Compounds were identified by comparison or their mass spectra, retention indices

(van den Dool and Kratz, 1962), and odor properties with those of authentic reference

standards.

Quantitation

MS response factors relative to the internal standard were used quantify selected

positively identified compounds. Extractions were performed as previously described ex

cept that

10

mL

of

deodorized water spiked with various amounts

of

each standard was

substituted for the cilantro sample.

Aroma Extract Dilution Analysis

GC-olfactometry was conducted on a Varian 3300 (or 3400) GC (Varian Instrument

Group, Walnut Creek, CA) equipped with a flame ionization detector (FID) and sniffing

port. Serial dilutions

l :3) were prepared in dichloromethane. Each dilution 3 ilL) was

analyzed using a capillary column (DB-WAX or DB-5ms, 30 m length x 0.32 mm i.d. x

0.25 f.lm dy J W Scientific). Column effluent was split 1:1 between FID and sniffing port

using deactivated fused silica capillary columns 1 m length

x

0.25 mm i.d.). FID and

sniffing port were maintained at a temperature

of

200°C. Sniffing port was supplied with

humidified air (30 mLlmin). GC conditions were the same as for GC-MS except that oven

temperature was programmed from 40°C to 200°C at a rate

of

6°C/min (or 10°C/min for

DB-WAX) with initial and final hold times

of

5 and 30 min, respectively. Further details

of AEDA have been previously described (Baek

et al., 1997 .


4/8

80

K. R. Cadwallader

et

al

RESULTS AND DISCUSSION

Volatile Composition o Cilantro

In our initial attempts at the isolation

of

cilantro volatiles we observed that sample

preparation and timing of extraction have a dramatic effect on extract composition and

variability of results.

To

minimize enzyme decomposition

of

volatiles during tissue disrup

tion it was necessary

to

maintain the fresh leaves in the presence of saturated sodium chlo

ride and under liquid nitrogen. Furthermore, we found it necessary to conduct solvent

extraction at

~ O ° C

Without the use

of

these measures, aldehyde content rapidly decreased

with an increase in corresponding alcohols data not shown). This phenomenon was re

ported by Smallfield et al 1993) for chopped cilantro and they suggested it might be due

to the presence of a nonspecific oxidoreductase. By employing the above measures it was

possible

to

minimize enzymatic reduction

of

aldehydes and obtain extracts with reason

ably high reproducibility Table

1 .

The incorporation

of

saturated salt during extraction

also served to retard enzyme action, such as lipoxygenase Buttery et al. 1994).

Volatile composition data for two cilantro samples are given in Table 1 The fresh

cilantro sample A) had both a greater number and higher abundance

of

volatile constitu

ents than the market sample sample B). The alkenals E)-2-decenal no. 9) and E)-2-do

decenal no. 18), and E)-2-tetradecenal no. 26) were in highest abundance in both

samples. Other alkenals found in both samples included E)-2-undecenal no. 13), E)-2-

tridecenal no. 22), E)-2-pentadecenal no. 27), and E)-2-hexadecenal no. 28). Sample A

contained several alkenals not detected in sample B e.g. nos 1,2,5,6 . Z)-3-hexenal no.

1 had not been previously reported in cilantro. Decanal no. 7) was the most abundant

saturated aldehyde in both samples, followed by undecanal no. 12 and dodecanal no.

18). Nonanal and tetradecanal were only detected in sample A, while tridecanal was found

only in sample

B

In addition to aldehydes, two alcohols, namely decanol no.

10

and E)-

2-decen-l-ol no. 11 were found at low levels in both samples.

Our quantitative results agree with those of Potter and Fagerson 1990) who found

E)-2-decenal , E)-2-dodecenal and E)-2-tetradecenal to be the major aldehydes in cilan

tro at the blooming stage. In a later study, Potter 1996) reported substantial differences in

E)-2-alkenal contents between two market cilantro samples. Unfortunately, neither of

these studies reported actual concentrations of these compounds, but instead estimated

their levels as percentages

of

the total area

of

all peaks detected. The present study is the

first to report concentration estimates of the major volatile constituents of cilantro.

Aroma Active Components o Cilantro

The aroma of fresh-cut cilantro has a typically pungent citrusy, soapy, and chlorine

like character. The two samples examined in the present study were considered to be typi

cal of fresh cilantro; however, the aroma of sample A was notably stronger had a

distinctive green and cut-leaf note that was lacking in sample

B.

The extracts prepared

from both samples were regarded by us as having the same aroma characteristics as the

original samples and were, therefore, suitable for aroma extract dilution analysis AEDA).

AEDA was conducted on two types

of

GC columns. Flavor dilution FD) chromato

grams determined on DB-WAX and DB-5ms columns are presented in Figures 1 and 2, re

spectively. The DB-WAX column yielded a total

of

10

detected dorants for sample A,

while only 8 odorants were detected for sample B. All odorants detected in sample B were

detected in sample

A.

Two odorants, Z)-3-hexenal green/cut-grass, no. I) and an un-


5/8

Character -Impact Aroma Components of Coriander

81

Table 1. Volatile components of cilantro

Retention index

b

Concentration

(Ilg/g)

No. Compound DB-5ms DB-Wax

Sample Ad

Sample

Be

Odor Description

f

Z)-3-hexenal

801

1137

2.02 ± 0.94)

g

green, cut-grass

2

E)-2-hexenal 854 1210 0.38 ± 0.16)

3

nonanal

1107 1388

0.13 (± 0.0.03)

4 unknown

1148 stale, old cut-grass

5

E)-2-nonenal 1163 1528 0.47 ± 0.10) stale, dry hay

6

(E )-4-decenal 1196 1540 green, citrus peel

7

decanal 1210 1494 10.6 ± 2.0) 5.56 ± 1.01) green, citrus peel

8 unknown

1249 1617 rancid, sour, old cut-grass

9

E)-2-decenal

1265

1639 59.2 ± 12.6)

2.41

±1.17) green, cut-grass, lettuce

10 decanol

1271

1765 0.39 ± 0.12) 0.0595 ±0.003)

II

E)-2-decen-I-ol

1274

1820 2.23 ± 0.58)

12 undecanal 1310 1599 0.23 ± 0.05) 0.35 ± 0.0 I

13

E)-2-undecenal

1369

1744 3.96 ± 0.68) 0.57 ±0.15) fresh, green, waxy

14

unknown

1379 green leaf

15

unknown 1398

1807 fresh, swimming pool area

16

dodecanal

1413

1705 0.38 (± 0.07) 1.03 ±0.09)

green

17

unknown

1453 green, waxy

18

E)-2-dodecenal

1476

1855 22.3 ± 3.2) 9.10 ±0.55) green, waxy

19

unknown 1503 fresh, swimming pool area

20 tridecanal 1510

1810 0.059

(±O.O

I)

21 unknown

1544 fatty, cheesy, waxy

22

E)-2-tridecenal

1574

1962

2.99 ± 0.56) 1.09 ±0.0.04) fatty, cheesy, waxy, floral

23 unknown 1604 fresh, swimming pool area

24 tetradecanal 1616 1917 0.18 ± 0.03)

25

unknown

1665 fish bowl

26 E)-2- tetradecenal

1685

2072 44.9 ± 8.4)

14.2

±0.16) fatty, waxy, cheesy

27

E)-2-pentadecenal

i

1784

2179 6.49 ± 1.0) 4.65 ±0.24)

28

E)-2-hexadecenal

i

1883 2288 4.86 ± 0.66) 1.93 (±O.I 0)

'Numbers

correspond to those in Figures

I and 2. bRetention indices calculated

from GC-O results.

'Average concentration

ex-

pressed

on wet

weight basis.

Numbers

in parantheses

are

standard deviations (n=3). dSample

A

was grown locally. 'Sample

was

obtained from

local

grocery

store.

fOdor descripiion

assigned

by panelists

during

GC-O. gCompound not

detected. hCompound

present at trace level. iCompound

tentatively

identified based

on

mass spectrum.

Quantitation

based on standard curve data

of

compound

no.

26.

known compound

rancid/sour/old

cut-grass, no.

8), had the highest log3FD-factors in

sample

A. Compound no. 1 was not detected in sample B, while 8 was detected at a low

log3FD-factor.

The

occurrence

of

Z)-3-hexenal

in

sample

A

was probably responsible

its

intense green and cut-leaf note. This odorant

has

a low odor detection threshold of

0.25

ppb

Buttery

t aI.

1987). Odorants having moderately high log3FD-factors in both sam

ples were decanal green/citrus peel,

no.

5), E)-2-decenal green/cut-grass/lettuce,

no. 9),

E)-2-undecenal fresh/green/waxy,

no. 13), E)-2-dodecenal green/waxy,

no.

18), and

E)-2-tridecenal fatty/cheesy/ waxylfloral, no. 22).

E)-2-Tetradecenal

fatty/waxy/

cheesy, no. 26) and an

unknown

fresh/swimming pool area, no. 15)

were

detected with

low log3FD-factors

in

both samples.

E)-2-Nonenal was only detected

in sample A

at

a

moderate

log3FD-factor.

The results of AEDA obtained on the DB-5ms column were superior those obtained

on

the DB-WAX

column

since more odorants were d etected in each of the

two

samples. A

total of 18 and 12 odorants were detected in samples A and B,

respectively.

Eleven of

these odorants

were

common to both samples. As was previously observed for the DB

WAX column, Z)-3-hexenal was only detected in sample A

and

had the highest

log3FD-


6/8

82

K. R.

Cadwallader et al

5

1

8

9

Sample A

3

5

13

18

2

7

i:

i

1

15

26

"$

:=

5

.$

E: ,

4

Q

Sample

B

3

18

2

7

9 13

22

1

8

15

26

o

11 12

13 14 15 16 17 18 19 2 2100

Retention Index DB-WAX)

Figure

1. Flavor dilution chromatograms for cilantro samples A and B determined on DB-WAX capillary column.

Numbers correspond to those in Table I and Figure 2.

factor in this sample. Two unknowns (no. 8 and 15) had the second highest log3FD-factors

in sample A followed by the 2-alkenals (nos. 13 18 and 22) and four odorants with mod

erately high log3FD-factors (nos.

5 7

9, 26). Compounds nos.

15

and

18

had the highest

log3FD-factors in sample B followed by nos.

7 8 13 22

and 26. Several odorants (nos.

19, 21, 23) had low log3FD-factors in both samples. Compounds nos. 4, 6, 14

17

and 25

were detected with low log3FD-factors in sample A only, while no.

16

was exclusively de

tected in sample

B.


7/8

Character Impact Aroma Components of Coriander

6

5

4

3

I:

2

0

1

0

a

0

' '

6

0

-

--

5

0

4

3

2

1

0

1

8

15

Sample A

13

18

22

5 7

9

26

\

6

4

17

19 21 23 25

Sample B

15

18

7 8

13

22 26

9

16

19

21

23

700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800

Retention Index (DB-Sms)

83

Figu re 2. Flavor dilution chromatograms for cilantro samples A and B determined on DB-5ms capillary column.

Numbers correspond to those in Table I and Figure I.

Due to its intense green/cut-grass aroma note, (Z)-3-exenal probably has the greatest

impact on the aroma of fresh-picked cilantro. However, this compound may not be an es

sential component of cilantro aroma since its absence from sample B did not alter the

cilantro-like character of

this sample. A similar observation could be made for com

pound no. 8, which was predominant in sample A but

of

low intensity in sample B The

(E)-2-alkenals from C9-C

14

would appear to be the most important components

of

cilan

tro aroma. We are uncertain as to which of these compounds

is

most important as the lev

els

of

these compounds could differ greatly for different cilantro samples. In addition to


8/8

84

K.

R. Cadwallader et

al

the E)-2-alkenals, three unknown odorants nos. 15,

19

and 23), which were described as

having fresh/swimming pool area-like aroma notes, may influence cilantro aroma. These

odorants provide a fresh chlorine-like note that can be readily detected

in

fresh-cut cilan

tro. Further work is in progress to elucidate the structures of these compounds.

This is manuscript no. BC-9257

of

the Mississippi Agricultural and Forestry experi

ment Station.

REFEREN ES

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muscadine grape juice. J Food Sci. 1997,62,249-252.

Buttery, R.O.; Takeoka, O.R.; Krammer, O.E.; Ling, L.C. Identification of 2,5-dimethyl-4-hydroxy-3 2H)-fura

none Furaneol) and 5-methyl-4-hydroxy-3 2H)-furanone in fresh and processed tomato. Lebensm.-Wiss.

u.-Technol. 1994 27 592-594.

Buttery, R.O.; Teranishi, R.; Ling, L.C. Fresh tomato aroma volatiles: a quantitative study. J Agric. Food Chem.

1987 35 540-544.

Carib10m A.J. Origin

of

coriander oil. Composition and structure of the components of the ethereal oil of the

flower stage

of

Coriandrum sativum.

J

Prakt. Chem. 1936,144,225-241 Chem. Abst. 1936,30,3772 .

Lawrence, B.M. Essential oil production. A discussion of influencing factors. In

Biogeneration

oj

Aromas;

Parli

ment, T.H. and Croteau, R. Eds.); ACS Symposium Series 317; American Chemical Society: Washington,

DC., 1986; Chapter 27, pp 363-369.

MacLeod, AJ.; Islam, R. Volatile flavour components of coriander leaf. J Sci. Food Agric. 1976,27, 721-725.

Mookherjee, B.D.; Wilson, R.A.; Trenkle, R.W.; Zampino, MJ.; Sands, K. New dimensions in flavor research:

herbs and spices. In Flavor Chemistry: Trends and Developments; ACS Symposium Series 338; American

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Potter, T.L.; Fagerson, I.S. Composition

of

coriander leaf volatiles.

J

Agric. Food Chem. 1990,38,2054--2056.

Potter, T.L. Essential oil composition

of

cilantro.

J

Agric. Food Chem. 1996,

44

1824--1826.

Scratz, E.; Qadry,

S.MJ.s.

Composition

of

essential oils in

Coriandrum

sativum

L.

III. Oil composition during on

togenesis. Planta Med. 1966, 14,436-442.

Smallfield, B.M.; Perry, N.B.; Bearegard, D.A.; Foster, L.M.; Dodds, K.O. Effects

of

postharvest treatments on

yield and composition

of

coriander herb oil. J Agric. Food Chem. 1993,42, 354--359.

van den 0001, H.; Kratz,

P.O.

A generalization of the retention index system including linear programmed gas-liq

uid partition chromatography. J Chromatogr. 1962,11,463-471.

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