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Abstract

Peel essential oil of bergamot (Citrus bergamia Risso) growing in Tunisia was separated by hydrodistillation and obtained in a yield of 9.7%. The oil composition was investigated using GC and GC-MS with two columns HP-1 and HP-Innowax. Fifteen compounds accounting for 98.52% of the oil were identified. The oil was characterized by high content of limonene (59.21%), linalool (9.51%) and linalyl acetate (16.83%).
Apr. 2010, Volume 4, No.4 (Serial No.29)
Journal of Chemistry and Chemical Engineering, ISSN 1934-7375, USA
Chemical Composition of Bergamot (Citrus Bergamia
Risso) Essential Oil Obtained by Hydrodistillation
Bouzouita Nabiha
1
, El Omri Abdelfatteh
1
, Kachouri Faten
1
, Casabianca Hervé
2
and Chaabouni Mohamed
Moncef
1
1. Higher Institute of Food Industries of Tunis, 58, Avenue Alain Savary, Tunis 1003, Tunisia
2. National Centre of the Scientific Research, Echangeur de solaize, Vernaison B .P. 22-69390, France
Received: October 9, 2009 / Accepted: October 27, 2009 / Published: April 30, 2010.
Abstract: Peel essential oil of bergamot (Citrus bergamia Risso) growing in Tunisia was separated by hydrodistillation and obtained in
a yield of 9.7%. The oil composition was investigated using GC and GC-MS with two columns HP-1 and HP-Innowax. Fifteen
compounds accounting for 98.52% of the oil were identified. The oil was characterized by high content of limonene (59.21%), linalool
(9.51%) and linalyl acetate (16.83%).
Key words: Citrus bergamia Risso, bergamot peel oil, essential oil composition, limonene, linalyl acetate.
1. Introduction
Citrus peel oils are widely used in the perfume and
cosmetic industries. Among them, bergamot (Citrus
bergamia Risso) peel oil is the most valuable essential
oil due to its unique fragrance and freshness. The
essence composed of a volatile part and non-volatile
fraction find application in the cosmetic, pharmace-
utical and food industries [1-3]. In the volatile fraction,
the oxygenated compounds are included in a superior
amount to that contained in other citrus essential oils
extracted from peels. This oxygenated terpene fraction
provides much of the characteristic flavor of bergamot
oil and its high amount makes this citrus essential oil
unique by its fragrance and aroma [4].
Many studies
concerning the chemical composition of the peel of
different varieties of citrus have been reviewed [5-9].
The bergamot essential oil produces in Reggio
Calabria, Italy, has been ranked as the highest quality at
the international trading market [10]. In 1994,
Corresponding author: Chaabouni Mohamed Moncef,
professor, research field: Valorization of the natural com-
pounds of origin vegetable. E-mail: chaabouni.medmon-
cef@iresa.agrinet.tn.
Mondello et al. [11] studied the chemical composition
of bergamot essential oil. They detected more than 100
volatile compounds in Italian bergamot oil, of which
linalyl acetate and linalool were predominant in
addition to limonene. In 1995, Giacomo and Mincione
[12] reviewed this chemical composition.
This study aims to investigate the oil composition of
bergamot peel obtained by hydrodistillation and to
compare it with composition of bergamot essential oil
provided by the Bergamot Consortium of Reggio
Clabria, Italy [10].
2. Experiment
Bergamot fruit was collected in November 2004
from Tunisia. Grated peel (50 g) were mixed with 200
ml H
2
O and subjected to hydrodistillation using
Dean-Stark apparatus (until there was no significant
increased in the volume of oil collection) to give the
following yield (w/w): 9.7%. The oil was dried over
anhydrous sodium sulfate and stored under N
2
at 4 .
The determination of retention data and the area
percentage of the identified constituents were carried
out on a two GC-FID systems.
Chemical Composition of Bergamot (Citrus Bergamia Risso) Essential Oil Obtained by Hydrodistillation
61
(1) An Agilent 5890 system equipped with HP-1 (ref
1909 1 Z-115) column (50 × 320 µm, 0.5 µm film
thickness). GC oven temperature was kept at 80 °C for
8 min and programmed to 220 °C at a rate of 2 °C /min.
(2) An Agilent 6890 system equipped with
HP-Innowax (ref 19091 N-216) column (60 m x 320
µm i.d., 0.5 µm film thickness). GC oven temperature
was kept at 60 °C and programmed to 245 °C at a rate
of 2 °C /min, then constant at 250 °C for 20 min.
The split ratio was adjusted to 1/100. The injector
temperature was 250 °C. The FID detector was kept at
250 °C. The carrier gas was helium (1.3 ml/min).
GC-MS analysis was carried out using the first
system, Agilent 5890 equipped with HP-1 column. The
mass spectra was recorded in the electron impact mode
at 70 eV using the aforementioned chromatographic
conditions. Individual components of bergamot peel
essential oil were identified by their retention indices
compared with literature values [13, 14] and their mass
spectra were interpreted on the basis of the WILEY 275
L computer library.
3. Results and Discussion
The compounds identified in the Tunisian Citrus
bergamia peel oil are listed in Table 1. The forty six
identified components constituted 98.52% of the total
oil. GC and GC–MS analysis showed that the oil
consisted of three main groups of constituents named
monoterpenes hydrocarbons, oxygenated monoter-
penes and sesquiterpenes. Bergamot peel oil studied
here contained 66.37% of monoterpenes hydrocarbons
with limonene as the major component (59.21%).
Furthermore, the oil contained 31% oxygenated
monoterpenes, the main components being linalyl
acetate (16.83%) and linalool (9.51%). The oil had
1.15% of sesquiterpenes. The main sesquiterpenes
were β-Bisabolene (0.47%) and Trans α-Bergamotene
Table 1 Chemical composition of peel Citrus bergamia
essential oil from Tunisia.
Kovats Indices
Compound Percentage HP-1 HP-Innowax
α-Thujene 0.01 924 1028
α-Pinene 0.48 932 1028
Camphene 0.02 945 1074
Sabinene 0.73 966 1126
β-Pinene 4.38 973 1118
Octanal 0.02 979 1273
Myrcene 1.23 981 1163
α-Phellandrene 0.07 993 1163
p-Cymene 0.03 1014 1271
Limonene 59.21 1029 1214
β- Phellandrene 0.14 1029 1219
(Z)-β-Ocimene 0.01 1033 1234
(E)-β-Ocimene 0.05 1037 1251
γ-Terpinene 0.01 1051 1251
(E)-Thujan-4-ol 0.01 1053 1463
(Z)-Linalool Oxide 0.02 1053 1451
(E)-Linalool Oxide 0.03 1072 1463
Terpinène 0.01 1080 1273
Linalool 9.51 1087 1542
(Z)-Limonene Oxide 0.18 1117 1451
(E)-Limonene Oxide 0.06 1124 1463
Citronellal 0.02 1131 1470
Terpinen-4-ol 0.05 1162 1601
α-Terpineol 1.09 1173 1691
Decanal 0.02 1184 1475
Octyl acetate 0.06 1192 1475
Nerol 0.28 1210 1788
Neral 0.28 1214 1681
Geraniol 0.62 1236 1833
Linalyl acetate 16.83 1244 1559
Geranial 0.27 1256 1730
Bornyl acetate 0.01 1270 1589
Terpinen-4-yl acetate 0.33 1287 -
Linalyl propionate 0.08 1331 1606
Citronnellyl acetate 0.18 1333 1681
Neryl acetate 0.4 1342 1721
Geranyl acetate 0.64 1360 1751
β-Bourbonene 0.01 1386 -
Decyl acetate 0.01 1392 -
(Z)-α-Bergamotene 0.02 1411 1574
β-Caryophyllene 0.1 1419 1606
(E)-α-Bergamotene 0.32 1433 1589
(E)-β-Farnesene 0.03 1447 1663
α-Humulene 0.01 1452 1677
γ-Muurolene 0.11 1471 1695
Germacrene D 0.02 1480 1720
Bicyclogermacrene 0.02 1493 1751
β-Bisabolene 0.47 1501 1728
Caryophyllene oxide 0.02 1571 1990
α-Bisabolol 0.01 1669 -
Total (%) 98.52
Chemical Composition of Bergamot (Citrus Bergamia Risso) Essential Oil Obtained by Hydrodistillation
62
(0.32%). The results obtained were compared with
those reported in the literature (bergamot oil produced
in
Reggio Calabria in Italy). The proportion of
limonene in bergamot peel essential oil from Tunisia is
high (59.21%) compared with that in essential oil
produced in Reggio Calabria (37.2%). It is know that
the ratio of linalool to linalyl acetate “essence degree”
is one of the quality indices of bergamot essential oil
and affects the aroma of the essence of bergamot. The
value of this ratio is 0.6 in the present work. The mean
ratio of bergamot oil produced in Reggio Calabria has
been reported to be approximately 0.3 [10].
According to the existing literature the oil of
bergamot peel obtained by cold-pressing consists of
limonene, linalool, linalyl acetate and non volatiles
compounds such as Bergamottin, Bergapten and
Citropten [1, 9]
which may be deleterious.
Pervaporation is reported as an alternative process to
the traditional techniques (steam distillation and
solvent extraction) used nowadays for extraction of
aroma compounds from natural matrixes [1]. The
extraction of essential oil from bergamot fruit with
enzymatic pre-treatment has been studied; the enzymes
have the function to degrade cell membrane and wall
allowing the almost total release of aroma compounds
[15]. Supercritical fluid chromatography was used in
order to investigate the possibility of detoxification of
this essential oil [9]. However, this purification may be
detrimental to the flavor of the oil, since the processed
oil will have a lower content of the oxygenated
terpenes which are responsible for the olfactory
characteristics [9].
4. Conclusions
The results of the oil composition obtained by
hydrodistillation showed a high proportion of limonene
(59.21%) and a high ratio of linalool to linalyl acetate
(0.6). This oil presents a good essence degree which is
better than thus of Calabria essential oil obtained by
expression.
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Citrus Essential Oils (CEOs) from the peel of six minor Citrus fruits (C. bergamia ‘Castagnaro,’ ‘Fantastico,’ and ‘Femminello,’ C. × myrtifolia , C. mitis, and C. japonica ) were obtained by hydrodistillation and cold hand pressing of the flavedo to investigate their volatile constituents and antimycotic activities. The volatile compounds present in the juices of the same fruits, obtained by manual squeezing of the endocarps, were evaluated by direct immersion and Solid Phase Micro Extraction. Monoterpenes were identified as the main class of components in all the six CEOs. Limonene was the most abundant compound, while BEOs (Bergamot Essential Oils) changed its composition according to the different extraction method and the fruit varieties. Non‐metric Multidimensional Scaling (NMDS) of the matrix taxa x chemical compounds showed that five chemical compounds had a significant discriminative function among the samples: high amounts of limonene characterized the cluster of C japonica , C . × myrtifolia, and C mitis , while the group of three cultivars of C bergamia differed in its predominance of linalool and linalyl acetate. Furfural and 4‐terpineol were identified in the highest amounts in the Citrus juices analyzed by direct immersion. BEO obtained by hydrodistillation of C bergamia ‘Fantastico’ was the most active in the antifungal tests. The antimycotic activity of C japonica EOs against dermatophytic species was also demonstrated. Based on our results, the use of these products would appear an interesting alternative in producing topical herbal products for the treatment of affected animals or for the purpose of environmental fungal control.
Thesis
Une triple attente socio-économique dans les domaines du développement durable (réduction des matières synthétiques non biodégradables), des solutions naturelles de conservation des aliments (tendance du « clean label » par la protection des denrées par des emballages actifs et intelligents évitant des additifs à outrance dans les aliments) et de la sécurité alimentaire (sécurité microbiologique et traçabilité) est à l’origine du développement de nouveaux matériaux à la fois biodégradables, comestibles et fonctionnalisés. Cette recherche commencée quelques décennies plus tôt est freinée par un mode de production difficilement industrialisable (voie solvant). Cependant, depuis quelques années des procédés applicables à l’échelle industrielle sont développées (voie fondue/extrusion). Dans le travail présenté ici, la technologie d’extrusion bivis a été appliquée avec succès sur différentes matières premières protéiques : la caséine acide, la caséine présure et le caséinate de sodium. Extraites toutes trois du lait de vache, ces caséines montrent des caractéristiques différentes qui affectent les propriétés du matériau (mécaniques, sensibilité aux molécules d’eau). La fonctionnalisation de la matrice par l’ajout d’acides organiques offre un potentiel antimicrobien intéressant contre Escherichia coli. Une complexation supplémentaire du matériau par incorporation de molécules hydrophobes telles que des cires (cires d’abeille, de candelilla et de carnauba) permet d’élargir une fois de plus l’éventail des propriétés disponibles pour ces matériaux composites, comme l’amélioration de la propriété barrière à la vapeur d’eau apportée par la cire d’abeille. La sensibilité aux molécules d’eau de ce type de matériau étant un critère à considérer à chaque étape de développement et de compréhension des interactions inter-ingrédients (protéine, plastifiant, cires, composés antimicrobiens). Ce manuscrit expose le potentiel de développement de matériaux à base de caséine, biodégradables, comestibles et antimicrobiens, qu’il s’agit d’appliquer en emballage agroalimentaire tout comme dans bien d’autres secteurs
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Peel and leaf oils of 58 mandarin cultivars, belonging to 15 different species were obtained from fruits and leaves collected on mandarin-trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition was investigated by capillary GC, GC/MS and NMR and the results were submitted to a cluster analysis and a discriminant analysis. Three major chemotypes, limonene, limonene/γ-terpinene and linalyl acetate/limonene, were distinguished for peel oils while three other chemotypes, sabinene/linalool, γ-terpinene/linalool and methyl N-methylanthranilate, were observed for leaf oils.
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The high-pressure phase behavior of the ternary system carbon dioxide+limonene+linalool was determined experimentally by a synthetic method. All the experiments were carried out in an approximately constant molar concentration of carbon dioxide equal to 98.00%. The ratio of limonene to linalool was varied from 0 to 1 through 12 different concentrations. Under these conditions, no liquid–liquid immiscibility was observed for this system. The data included bubble points, critical points and dew points within a temperature and pressure range of 293–349K and 5–14MPa, respectively. The results were compared with ternary data of ethane+limonene+linalool at similar conditions of constant supercritical fluid concentration and varying limonene to linalool ratios. The results indicated that supercritical extraction of citrus oils could be carried out at lower pressures if ethane is used instead of carbon dioxide.
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A fully automatic on-line LC-GC-MS system for the analysis of bergamot essential oil has been used. The system allows the pre-separation by LC of the oil into compound classes by gradient elution followed by the transfer of these fractions into a capillary GC column and detection by MS (ITD) and FID. Combining LC-GC-MS produces data which are considerably more informative than data from GC-MS of the whole essential oil.
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The volatile components of bergamot (Citrus bergamia Risso) essential oil produced in Reggio Calabria in Italy were investigated using GC, GC–MS and gas chromatography–olfactometry (GC–O). Fifty-five compounds in the oil were identified by GC and GC–MS. The major compounds were limonene (37.2%), linalyl acetate (30.1%), linalool (8.8%), -terpinene (6.8%) and β-pinene (6.2%). In sensory analysis, odour description and flavour dilution (FD) factors of each component were evaluated by GC-sniffing and aroma extraction dilution analysis (AEDA). Bergamot-like odour components were (Z)-limonene oxide, decanal, linalyl acetate and geraniol. A mixture of eight other components, such as limonene, linalool, -terpinene and others, in addition to the four bergamot-like aroma compounds, brought about an aroma model of bergamot odour with the similarity of 7.1 by the nine-point-score sensory test. Copyright © 2006 John Wiley & Sons, Ltd.
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A fully automated HPLC-HRGC-MS(ITD) system was used for the analysis of the terpene hydrocarbon fraction of eight essential oils: bergamot, lemon, mandarin, sweet orange, bitter orange, grapefruit, clementine and Mexican lime. The system allows the isolation by LC of the hydrocarbon fraction followed by transfer into the GC and identification of the single components by MS(ITD). LC-GC-MS coupling gives more accurate results than those obtained from GC-MS analysis of the whole essential oil. The results obtained were compared with those reported in the literature, and represent a reference for the characterization of the citrus essential oils.
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The efficiency of separation of bergamot essential oil, performed by a countercurrent column filled with Raschig rings and using supercritical carbon dioxide as partition solvent, is affected by various parameters. In the experiments explained in this work, the direct effect of CO2 density was shown and the ratio between the amount of oil loaded to on the column and the amount of CO2 used were discussed. The conditions that produced extracts with a similar volatile fraction composition of starting material and with a high yield (more than 80% of recovery) were those with a low feed:solvent ratio; the lowest bergaptene content was obtained at low CO2 density or at high feed:solvent ratio. A good result was observed at a CO2 density of 206 g/dm(3) (8 MPa of pressure and a temperature gradient of 46-50-54degreesC) and a feed:solvent ratio of 9.4-9.6; in this separation, a yield of 74-77% and a bergaptene content lower than 0.01% was measured. Copyright (C) 2003 John Wiley Sons, Ltd.
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Supercritical fluid chromatography was used in order to investigate the possibility of detoxification of an essential oil. Bergamot peel oil contains phototoxic compounds, the psoralens, which must be removed prior to its use. The retention of the major constituents of the oil was determined under various levels of pressure (from 75 to 160 bar) and temperature (37 to 57°C) of pure carbon dioxide. The highest selectivity against psoralens, and specifically, against bergapten was obtained at low pressure and high temperature. Bergapten elimination was then successfully achieved by adsorption from a supercritical feed.
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Bergamot peel oil is the most valuable essential oil due to its unique fragrance and freshness. The essence finds application in the cosmetic, pharmaceutical and food industries. However, strong limitations have been imposed on its use since bergamot oil contains several coumarins and psoralens which may be photoactive. Qualitative and quantitative analyses with GC–MS were carried out to evaluate the aroma flavour bouquet of the bergamot essential oil obtained by pervaporation (PV). In all PV experiments, made at different ethanol feed concentration and temperature, the bergapten was not detected in the permeate while the aroma components, present in the feed, permeate through the commercial Pervap 1070 membrane. Bergapten is a photoactive component of bergamot essential oil which, in combination with UV radiation, promotes melanogenesis and causes thickening of the stratum corneum. Therefore, PV is a valid alternative for the high quality of essential oil produced without bergapten to the traditional techniques employed in which the bergapten can be removed after an extra-chemical treatment.
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The concentration of bergamot peel oils by pervaporation, with and without enzymatic pre-treatment, is studied. The influence of different PV membranes, industrial enzymes and operational parameters on the PV process are also investigated. GC-MS analyses are carried out to evaluate the recovery of the main aroma compounds such as linalool, linalyl acetate and limonene.