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The minimum inhibitory concentrations (MIC) of crude essential oil of cilantro (Coriandrum sativum L.) and four fractions recovered by fractional distillation of the crude oil were determined against strains of Listeria monocytogenes, Listeria grayi, Listeria innocua and Listeria seeligeri. Crude oil inhibited all the test strains at concentrations ≤ 0.01% (v/v) and the remaining fractions were effective at concentrations < 0.07% (v/v). One fraction comprising a complex mixture of alcohols, aldehydes, alkanes and terpenes, including high concentrations of (E)-2-decenal, exhibited slightly greater potency than the other fractions. Listericidal activity was demonstrated by a rapid loss in cell viability upon exposure to crude oil dissolved in Tryptic Soy Broth. Cilantro oil is a potent antilisterial plant extract with potential applications as a food preservative or in the formulation of disinfectants for the control of Listeria monocytogenes in the food processing environment.
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Cilantro
Vol. 16, September/October 2004 Journal of Essential Oil Research/409
Received: March 2003
Revised: April 2003
Accepted: April 2003
Antilisterial Properties of Cilantro Essential Oil
Pascal J. Delaquis
*
and Kareen Stanich
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97, Summerland, British
Columbia, Canada V0H 1Z0
Abstract
The minimum inhibitory concentrations (MIC) of crude essential oil of cilantro (Coriandrum sativum L.) and
four fractions recovered by fractional distillation of the crude oil were determined against strains of Listeria
monocytogenes, Listeria grayi, Listeria innocua and Listeria seeligeri. Crude oil inhibited all the test strains at
concentrations 0.01% (v/v) and the remaining fractions were effective at concentrations < 0.07% (v/v). One fraction
comprising a complex mixture of alcohols, aldehydes, alkanes and terpenes, including high concentrations of (E)-2-
decenal, exhibited slightly greater potency than the other fractions. Listericidal activity was demonstrated by a rapid
loss in cell viability upon exposure to crude oil dissolved in Tryptic Soy Broth. Cilantro oil is a potent antilisterial plant
extract with potential applications as a food preservative or in the formulation of disinfectants for the control of
Listeria monocytogenes in the food processing environment.
Key Word Index
Coriandrum sativum, Apiaceae, cilantro, Listeria spp., antilisterial activity, essential oil composition, linalool,
(E)-2-decenal, (E)-2-decenol, decanol, decanal, carvone.
1041-2905/04/0005-0409$6.00/0—© 2004 Allured Publishing Corp.
J. Essent. Oil Res., 16, 409-414 (September/October 2004)
*Address for correspondence
Introduction
Recurring outbreaks of food borne illness caused by List-
eria monocytogenes have sustained the demand for preserva-
tion systems that limit the proliferation of this psychrotrophic
pathogen in refrigerated foods. The development of suitable
control strategies for this pathogen would benefit from the
availability of functional, effective antilisterial preservatives.
Several spices, herbs, plant extracts and essential oils are
known to inhibit species of the genus Listeria (1-6). Unfortu-
nately, attempts to eliminate or control the growth of L.
monocytogenes in foods with antimicrobials from plants often
yield disappointing results (3,7-9). Several explanations have
been put forward to explain the limited efficacy of plant
extracts in food systems. These include, but may not be
limited to, insufficient or assumed understanding of mode of
action, poor solubility in the aqueous phase, partitioning of
the antimicrobials in the lipid phase and loss in activity due to
reactions with food components. In addition, effective control
of L. monocytogenes in foods often requires concentrations
that affect sensory quality due to the aromatic nature of most
antimicrobial phytochemicals. There is clearly a need for
more potent antilisterial agents and for better characteriza-
tion of their mode of action.
An evaluation of the antimicrobial properties of various
plant essential oils by Delaquis et al. (10) revealed that steam
distillates of cilantro (the immature plant of Coriandrum
sativum L., source of coriander seed) are highly effective
against L. monocytogenes. Cilantro oil was also far more
potent than the oil derived from coriander seed. To our
knowledge, the antilisterial properties of cilantro oils has not
been described previously, and the mechanisms underlying
inhibition are unknown. The purpose of the present investiga-
tion was threefold: to verify the spectrum of activity against
several strains of the genus Listeria; to determine which
component(s) of cilantro oil are responsible for antilisterial
activity; and to determine whether the oil exerts bacteriostatic
or bactericidal activity against species from this genus.
Experimental
Microorganisms and cultural methods: Listeria strains
and their origins are provided in Table I. Stock cultures were
maintained at 4°C on plates of Trypticase Soy Broth (BBL,
Cockeysville, MD) amended with 5 g/L Yeast Extract and 15
g/L Agar (TSAYE). Active cultures were prepared by transfer-
ring cells from the stock cultures to 10 mL of Trypticase Soy
Broth amended with 5 g/L Yeast Extract (TSBYE), followed
by incubation for 24 h at 30°C. Inocula for experiments were
prepared by dilution of the cultures with fresh TSBYE and
spectrophotometric (620 nm) adjustment to reach the desired
cell densities according to standard curves for each strain
(data not shown).
Cilantro oil and oil fractions: Crude cilantro oil was
obtained from Northern Essentials Ltd. (Prince Albert, SK,
Canada). Several fractions of variable chemical composition
Delaquis and Stanich
410/Journal of Essential Oil Research Vol. 16, September/October 2004
were recovered by fractional distillation of the crude oil in
batch mode under vacuum using a custom built, proprietary
column. Four separate fractions were retained for further
study. Chemical composition, provided in Table III, was
determined by gas chromatography/mass spectroscopy as
described in Delaquis et al. (10). Crude and fractionated
cilantro oil fractions were diluted in hexane (approximately
25.0 mg/25 mL). Aliquots (1 µL) were injected with an
autosampler (model 7673A, Hewlett Packard, Avondale, PA)
into a gas chromatograph (model HP 5890) equipped with a
flame ionization detector and an HP 3396A integrator. Com-
ponents were separated on a Supelcowax 10 fused silica
capillary column (60 m x 0.25 mm, 0.25 µm film thickness)
with helium as a carrier gas and nitrogen make-up gas. The
column pressure was maintained at 207 kPa (30 psi) and the
injector split ratio was set at 20:1. Injector and detector
temperatures were both set at 250°C, and the oven was
programmed to increase from 35°-200°C at a rate of 3°C/min,
followed by a hold time of 10 min. Quantitative data were
obtained from area percent data without the use of correction
factors.
Mass spectral data were obtained from an HP 5890-5970
GC-MSD system. The mass spectrometer operated with an
ion source at 250°C, ionizing energy of 70 eV, scan range of 25-
250 amu, threshold at 400, and a frequency of 2.6 scans/s.
Programming of column and temperature for separation was
similar to that applied in the analytical GC-FID, as described
above. Individual components were identified using HP
G1034C MS ChemStation software containing an HP G1035A
Wiley (138.1) PBM library. Where possible, identity confir-
mation was accomplished by comparing retention times with
reference standards (Aldrich Chem. Co., Milwaukee, WI).
Determination of minimum inhibitory concentra-
tions: Minimum inhibitory concentrations (MIC) were deter-
mined by a miniaturized broth dilution assay in microtiter
plates using methods derived from those of Mann and Markham
(11). Crude cilantro oil and oil fractions were serially diluted
in TSBYE + 0.30% agar (w/v) and dispensed (120 µL) into
rows of wells in microtitre plates (96 x 320 µL wells, Becton
Dickinson, NJ) with a multi-channel micro-pipettor, to achieve
a range of concentrations from 0-0.11% (v/v) in 0.01% incre-
ments. Individual bacterial cultures (120 µL) were added to
separate columns of wells and were mixed with the medium
using the micro-pipettor. The final agar concentration was
0.15% (w/v) and the inoculum level was approximately 1.0 x
10
6
cfu/mL for each strain. All plates were incubated at 30°C
with the lids on. The wells were examined for evidence of
growth after 24 and 48 h, and MIC values were determined as
the lowest antimicrobial concentration that inhibited visible
growth of the test microorganisms. Three experiments were
performed with each strain.
Effect of the oils on viability of Listeria sp.: Screw cap
test tubes (30 mL) filled with 25 mL TSBYE + 0.15% agar
containing 0.01% (v/v) crude cilantro oil were tempered to
30°C in a waterbath. At timed intervals the tubes were inocu-
lated with 0.25 mL of culture, mixed by vortexing and were
returned to the waterbath. Samples were withdrawn 0.04, 0.5,
1, 2, 3, 6, 24, 48 and 169 h after inoculation. Surviving cell
populations were estimated by spreading samples suitably
diluted in TSBYE onto TSAYE, followed by incubation at
30°C for 48 h. Recovery of cells below the detection limit (10
cfu/mL) was ensured by enrichment of a 1.0 mL sample in 100
mL TSBYE at 30°C for up to seven days. Fluids from positive
enrichments were spread onto PALCAM Agar (Difco). Typi-
cal Listeria colonies (ie. esculin hydrolysis positive) were
examined for Gram staining reaction (KOH method), motility
and catalase reaction for presumptive confirmation.
Results and Discussion
Minimum inhibitory concentrations for crude cilantro oil
and various fractions obtained by fractional distillation are
shown in Table II. Crude cilantro oil added to TSBYE at a
level 0.01% (v/v) inhibited growth of all the Listeria spp.
tested. Growth was evident in microtiter plate wells contain-
ing lower concentrations of crude oil, thus attempts to mea-
sure MICs at concentrations 0.01% (v/v) using the method
chosen for this work were unsuccessful. The remaining oil
fractions were all effective at concentrations < 0.07% (v/v).
Fraction 2 was the second most potent tested, and fractions 1,
3 and 4 yielded consistently higher MIC values. While sensi-
tivity varied between species, no differences were apparent
for individual strains of L. monocytogenes. Strict comparison
with antilisterial activities reported for other plant essential
oils is not possible given the variability in composition, meth-
odologies and microbial strains employed for individual stud-
ies (12). Nevertheless, the present results confirm the apparent
ascendency of cilantro oil antilisterial activity compared to
other plant extracts examined to date. For example, Pandit
and Shelef (3) reported that growth suppression of L.
monocytogenes in Brain Heart Infusion Broth required supple-
mentation with 0.1% (v/v) rosemary oil.
Chemical analysis of the oils (Table III) revealed that the
crude oil and fraction 2 comprised more heterogeneous mix-
tures of alcohols, aldehydes, alkanes and terpenes than frac-
tions 1, 3 and 4. Both also contained greater amounts of
(E)-2-decenal, which possibly contributed to the antilisterial
effect given the antimicrobial properties of this compound
(13). However, the remaining fractions retained strong activ-
Table I.
Listeria
strains used in the assessment of antilisterial
activity in cilantro oil
Strain Origin
L. grayi
Beef isolate, Lacombe Research
Centre, AB, Canada.
Listeria
sp. Chinese parsley isolate, Health
Canada, Ottawa, ON, Canada.
L. innocua
Watercress isolate, Health Canada,
Ottawa, ON, Canada.
L. seeligeri
Lettuce isolate, PARC, BC, Canda.
L. monocytogenes
1 Cabbage isolate, LCDC 81-861.
L. monocytogenes
2 Frozen egg yolk isolate, AAFC,
Guelph, ON, Canada.
L. monocytogenes
3 Chicken wiener isolate, AAFC,
Guelph, ON, Canada.
L. monocytogenes
4 Institut Pasteur, Paris, France.
Cilantro
Vol. 16, September/October 2004 Journal of Essential Oil Research/411
ity despite the scarcity of (E)-2-decenal. These observations
indicate that the overall antilisterial activity of crude cilantro
oil was not derived from a single compound or group of
compounds, but rather from complex interactions between
individual chemical constituents. A similar conclusion was
reached for essential oils and oil fractions of dill, coriander
and eucalyptus tested against a range of microorganisms (10).
Despite the lack of an obvious, single actuating chemical or
group of chemicals, comparisons were made with MIC data to
establish possible associations with antilisterial activity. Of
note was the abundance of medium chain length alcohols
(particularly octanol and decanol) in oil fractions 1, 3 and 4.
The latter are major constituents of distilled C. sativum leaves
(14) and are known to possess antimicrobial activity, particu-
larly against Gram-positive bacteria (15,16). The observations
reported herein indicate that they are also active against L.
monocytogenes, and further assessment of their antilisterial
activity is clearly warranted. Interestingly, MICs for the crude
oil and fraction 2 were generally similar after 24 or 48 h
incubation, while a consistent increase was noted for fractions
1, 3 and 4. A gradual loss of alcohols due to the volatility of
these compounds could explain the apparent increase in
MICs over time.
The effect of cilantro oil on viability of Listeria sp. was
verified in TSBYE supplemented with oil at a level of 0.01%
(v/v). Figure 1 shows populations of viable L. monocytogenes
cells after variable times of exposure. Strains 1, 2 and 4 were
completely inactivated by the oil and could not be recovered
by enrichment. The effect was generally achieved after 3 h of
exposure. L. monocytogenes strain 3 was more resistant to the
oil and growth of this strain resumed after 24 h in two of three
replicate trials. Medium from both trials was applied to
freshly prepared plates of TSBYE + 0.01% (v/v) cilantro oil
after 48 h incubation to verify whether the cells had acquired
resistance to the oil. No growth was observed after 72 h.
Potential changes in sensitivity were also verified by perform-
Table II. Minimum inhibitory concentrations (MIC, % v/v) of crude cilantro oil and distilled fractions against several
Listeria
strains
after 24 and 48 h incubation at 30°C
24 h 48 h 24 h 48 h
MIC MIC MIC MIC
Crude cilantro oil
L. grayi
0.01
1
0.01 to 0.02
L. monocytogenes
1 0.01 0.01
Listeria
sp. 0.01 0.01
L. monocytogenes
2 0.01 0.01
L. innocua
0.01 0.01
L. monocytogenes
3 0.01 0.01
L. seeligeri
0.01 0.01
L. monocytogenes
4 0.01 0.01
Cilantro fraction 1
L. grayi
0.03 - 0.04 0.04 - 0.06
L. monocytogenes
1 0.04 0.05 - 0.07
Listeria
sp. 0.03 - 0.04 0.04 - 0.06
L. monocytogenes
2 0.03 - 0.04 0.05 - 0.06
L. innocua
0.03 - 0.04 0.04 - 0.06
L. monocytogenes
3 0.03 - 0.04 0.05 - 0.07
L. seeligeri
0.03 - 0.04 0.05 - 0.06
L. monocytogenes
4 0.03 - 0.04 0.05 - 0.06
Cilantro fraction 2
L. grayi
0.01 - 0.02 0.02
L. monocytogenes
1 0.01 - 0.02 0.02
Listeria
sp. 0.01 0.02
L. monocytogenes
2 0.01 - 0.02 0.02
L. innocua
0.01 ± 0.02 0.02
L. monocytogenes
3 0.02 0.02
L. seeligeri
0.01 0.02
L. monocytogenes
4 0.01 - 0.02 0.02 - 0.03
Cilantro fraction 3
L. grayi
0.02 - 0.03 0.04 - 0.05
L. monocytogenes
1 0.02 0.03 -0.04
Listeria
sp. 0.02 - 0.03 0.03 - 0.05
L. monocytogenes
2 0.02 0.03 - 0.04
L. innocua
0.02 0.03 - 0.04
L. monocytogenes
3 0.02 0.04
L. seeligeri
0.02 0.03
L. monocytogenes
4 0.02 0.03 - 0.04
Cilantro fraction 4
L. grayi
0.03 0.04 -0.07
L. monocytogenes
1 0.03 - 0.04 0.05 - 0.06
Listeria
sp. 0.03 - 0.04 0.05 - 0.07
L. monocytogenes
2 0.03 - 0.04 0.05 - 0.07
L. innocua
0.02 - 0.03 0.03 -0.05
L. monocytogenes
3 0.03 - 0.04 0.05 - 0.06
L. seeligeri
0.02 - 0.03 0.03 - 0.05
L. monocytogenes
4 0.03 - 0.04 0.05 - 0.06
1
values represent the range of MICs measured in three independent experiments
Delaquis and Stanich
412/Journal of Essential Oil Research Vol. 16, September/October 2004
Table III. Percentage composition of major volatile components of cilantro oil and of fractions recovered by fractional distillation
Distilled fractions
Crude oil
1
1234
nonane 2.5 0.1 0.1 - -
α-pinene 2.7 ----
limonene 1.8 - 0.1 - -
γ-terpinene 0.9 ----
p-cymene 3.5 0.3 0.4 0.2 -
(Z)-3-hexenol 0.3 ----
decanal 8.4 21.7 3.2 0.6 0.7
camphor 1.9 4.4 0.3 - -
linalool 25.9 11.5 1.2 0.4 -
octanol 0.3 15.2 9.9 1.1 0.4
(E)-2-decenal 20.2 6.9 43.1 4.6 1.7
carvone 1.2 12 18.1 2.5 0.2
decanol 3.9 - 0.4 25.8 15.2
(E)-2-decenol 7.9 - 0.8 36.2 12.8
Unknown - - - 1.0
2
44.3
3
Total 91.4 72.1 77.6 72.4 75.5
1
values represent the relative abundance (%) of each compound;
2
m/z (%) - Unknown: 190 (39), 172 (1), 161 (9), 159 (1), 157 (1), 147 (7), 133 (9), 131 (4), 120 (100),
119 (74), 105 (13), 103 (8), 91 (88), 79 (8), 77 (18), 65 (25);
3
m/z (%) - Unknown: 204 (15), 161 (3), 147 (4), 133 (4), 120 (46), 119 (29), 105 (9), 103 (5), 92 (31), 91 (31),
77 (6), 65 (10)
Figure 1. Fate of four
L. monocytogenes
strains incubated at 30°C in Tryptic Soy Broth amended with 0.01% (v/v) cilantro oil;
results obtained from three independent experiments are shown; viable cells were recovered by enrichment at sampling
times marked with a vertical arrow
Cilantro
Vol. 16, September/October 2004 Journal of Essential Oil Research/413
ing MIC determinations on isolates recovered from the en-
richment cultures. This yielded MICs of 0.01% (v/v), values
identical to those determined for the stock cultures. The
effect of cilantro oil on four additional Listeria species is
shown in Figure 2. L. grayi was highly susceptible to the
antilisterial effect and the decline in cell viability was fastest
among the strains examined. However, growth resumed in
one replicate trial. A similar pattern was observed with the
Listeria sp.
Rapid losses in viability observed with all strains provided
evidence that cilantro oil possesses strong listericidal activity.
The effect was not always complete however, and some cells
resumed growth after exposure to the oil. It is tempting to
conclude that part of the cell population was resistant, or
developed resistance to cilantro oil. The latter contains a
complex mixture of antimicrobial components however, and
simultaneous resistance to such a broad range of chemicals is
unlikely. The multiplicity of potentially toxic components in
the oil would also preclude the possibility of acquiring resis-
tance through spontaneous mutation within the time frame of
the experiment. A more plausible explanation is that active
chemical components were lost or degraded within 24 h,
thereby allowing sub-lethally injured cells to repair and re-
sume growth. Depletion of active principles through chemical
reactions with food components is believed to interfere with
long term protection against microbial growth in foods supple-
mented with antimicrobial plant extracts (9). Many of the
active principles in cilantro oil, particularly phenolic com-
pounds, are also volatile, prone to oxidation, and readily react
with proteins. Such limitations could hamper potential appli-
cations for cilantro oil in food preservation until means are
found to ensure lasting stability, by encapsulation for example.
More immediate, practical uses for cilantro essential oil can
be envisaged however, including the formulation of sanitizers
or topical disinfectants for the control of L. monocytogenes
and other hazardous microorganisms in the food-processing
environment.
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... 53 The essential oil from C. sativum herb (cilantro) typically has as its major components linalool (0%-26%), decanal (3%-20%), (2E)-decenal (1%-30%), (2E)-decen-1-ol (0%-19%), 1-decanol (2%-36%), (2E)-undecenal (0%-5%), (2E)-dodecen-1-ol (0%-18%), (2E)-tetradecenal (0%-13%), and (2E)pentadecenal (4.8%). 43,[54][55][56][57][58][59][60][61] The high concentrations of unsaturated aldehydes in cilantro are the source of the aroma of the herb as well as the source of the well-documented preference or disdain for cilantro. 62 (2E)-Decenal has been described as having a fatty, pungent odor; (2E)-dodecenal has a floral, pungent odor; (2E)-tetradecenal has a pungent, spicy, floral odor; while the unsaturated alcohol, (2E)-decen-1-ol, has been described as having a wet dog odor. ...
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Coriander and cilantro, the fruit and herb of Coriandrum sativum, are popular additives in various cuisines worldwide. The essential oils derived from coriander and cilantro are also popular and have shown some remarkable biological properties and health benefits. In this report, we have analyzed the essential oil compositions of 19 commercial coriander and 28 commercial cilantro essential oil samples by gas chromatography–mass spectrometry (GC–MS) techniques. In addition, 5 coriander and 4 cilantro commercial essential oil samples were analyzed by chiral GC–MS. Commercial coriander essential oil is dominated by linalool (62.2%-76.7%) with lesser quantities of α-pinene (0.3%-11.4%), γ-terpinene (0.6%-11.6%), and camphor (0.0%-5.5%). Commercial cilantro essential oil is composed largely of (2 E)-decenal (16.0%-46.6%), linalool (11.8%-29.8%), (2 E)-decen-1-ol (0.0%-24.7%), decanal (5.2%-18.7%), (2 E)-dodecenal (4.1%-8.7%), and 1-decanol (0.0%-9.5%). The enantiomeric distribution of linalool was 87% (+)-linalool:13% (−)-linalool in both coriander and cilantro essential oils, while α-pinene was 93% (+):7% (−) in coriander, 90% (+):10% (−) in cilantro; and (+)-camphor:(−)-camphor was 13%:87% in both essential oils. Chiral GC–MS analysis was able to detect an adulterated coriander essential oil sample. The data provided in this study serves to establish a baseline for future evaluations of these essential oils as well as a screen for authenticity or adulteration.
... The inability of EOs to completely eradicate biofilm growth in the present study also confirmed that biofilm cells are more resistant than planktonic cells to antimicrobial agents. Previous studies have reported that the antimicrobial effect of EOs can be attributed to interactions among EO components and not to any individual component (Delaquis and Stanich 2004;Elexson et al. 2013, Mourey andCanillac 2002). The resistance of biofilms to complete eradication by EOs may be because the EOs were used individually to treat the biofilm. ...
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The antibacterial activity against Streptococcus mutans of a number of naturally occurring compounds was tested. The emphasis was placed on a series of long-chain alcohols to gain new insight into their structural functions. Maximum activity seems to depend on the hydrophobic chain length from the hydrophilic hydroxyl group. Among the alcohols tested, 1-tridecanol was found to be the most effective for controlling this cariogenic bacterium.
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The effects of the postharvest treatments of chopping and storage on the yield and composition of coriander herb oils from pilot-scale steam distillations are reported. Chopping the plant material gave an average 10.4 L/ha increase in oil yield. The oil composition is also changed by chopping and storage. The relative levels of the aldehydes [(E)-2-decenal is the major one] fall and the relative levels of alcohols rise with increased time of storage. However, oil yields drop after storage for more than 4 h. Small-scale solvent extracts confirmed these results.
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