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Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization122
7
Characteristics Variation of Lavender Oil
Produced by Different Hydrodistillation
Techniques†
G.D. KIRAN BABU★ AND BIKRAM SINGH
Natural Plant Products Division, Institute of Himalayan Bioresource Technology
(CSIR), P.O. Box No. 6, Palampur – 176 061, Himachal Pradesh, India
★Corresponding author : E-mail : gdkiran@ihbt.res.in
†IHBT Communication Number: 0838.
ABSTRACT
Lavender (Lavandula angustifolia Mill.) grown in the agro-climatic
conditions of western Himalaya was processed for extraction of volatile
oil by different hydrodistillation techniques which revealed that water
distillation of the herb produced higher yield (1.6%) than that of
water-steam distillation (1.1%) and steam distillation methods (0.9%).
The samples were analysed by GC and GC-MS to study and compare
the essential oil composition and observed that the highest
monoterpene hydrocarbon (10.05 %) and sesquiterpenoid (10.28%)
content was observed in the oil produced by steam distillation method
followed by water-steam distillation (6.31% and 7.73%) and water
distillation (5.62% and 3.18%, respectively) methods. Higher ester
content (50.44%) was observed in the oil produced by water-steam
distillation followed by steam distillation (41.29%) and water
distillation (35.52%). Linalyl acetate, one of the quality determining
constituents of lavender oil, was recovered in higher amount from
the oil produced by water-steam distillation (47.1%). The lowest
linalyl acetate (30.01%) was recovered in the oil produced by water
distillation method followed by steam distillation method (35.28%).
On the contrary, the total alcohol content was found in higher
quantities in the oil produced by water distillation method (52.32%)
followed by steam distillation method (35.58%) and lowest in water-
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
123
INTRODUCTION
True lavender (Lavandula angustifolia Mill. Syn. L. officinalis Chainx.)
is distributed in the mountainous districts of southern Europe,
bordering of western half of Mediterranean and extending from the
eastern coast of Spain, France, Switzerland, North Italy, Corsica and
north Africa. About twenty years back, an effort was made to cultivate
this plant on large scale in Kashmir valley in India to meet the
requirements of Indian market. However, commercial production did
not increase due to political disturbances (Vaze, 2000). India imports
100 tons lavender oil annually (Shawl et al., 2005). In this regard,
Institute of Himalayan Bioresource Technology, Palampur, initiated
the extension of the plantation and commissioned distillation units
in district Chamba, Himachal Pradesh, India with an objective to
produce sufficient quantities for meeting the industry requirement.
Lavender oil, obtained from the flowering tips, is used in
aromatherapy and has calmative, anti-flatulence, and anti-colic
properties (Lis-Balchin and Hart, 1999). The primary use of lavender
oils, however, is as raw ingredients in industrial perfume and
fragrance materials, with the bulk of this market filled by lavandin
oil. (McGimpsey & Porter, 1999). Lavender oil is characterized by
high levels of linalool and linalyl acetate, moderate levels of lavandulyl
acetate, terpinen-4-ol and lavandulol.
Inadequacy in Hydrodistillation
Hydrodistillation of essential oils suffer several limitations in isolating
and preserving the composition of natural fragrances. It produces
the degradation of thermo labile compounds and hydrolysis of water
steam distillation method (31.86%). These variations in the quality of
lavender oil produced by different hydrodistillation methods could be
due to the thermal degradations during the process and number of
other chemical reactions such as allylic rearrangements, hydrolysis,
elimination etc. Based on the present experimental condition, it is
recommended that the lavender oil, on commercial scale, may be
produced preferably by water-steam distillation method to reduce the
by-product formation by various chemical reactions and to get better
oil recoveries. Furthermore, the capital investment for the water-
steam distillation unit will be much lower than the steam distillation
system, as it wouldn’t require a separate boiler.
Key words : Essential oil, hydrodistillation, Labiatae, Lavandula
angustifolia Mill., lavender oil, linalool, linalyl acetate,
steam distillation
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization124
sensitive compounds. During hydrodistillation, esters present in
essential oils are generally hydrolyzed by the release of H+ ions from
water. In the presence of water, at about its boiling point, esters
hydrolyze to the corresponding acids and alcohols.
at higher
temperatures
Esters + water Corresponding acids and alcohols
The hydrolysis of esters in the geranium oils during
hydrodistillation has been discussed extensively by Babu and Kaul
(2005). Major ester present in the lavender oil is linalyl acetate, an
important quality determining constituent (Wiesenfeld, 1997). Due
to high temperatures and unfavorable conditions prevailing during
the hydrodistillation process, esters undergo molecular
rearrangements and elimination reactions leading to degradation of
molecules. Pickett et al. (1975a) examined a model system in which
pure linalyl acetate was subjected to steam distillation with pH 4.
The composition of the steam distillate was found to contain myrcene
(3.7%), limonene (1%), cis-ocimene (1.7%), trans-ocimene (3.3%), a-
terpineol (19.7%), neryl acetate (4.3%), geranyl acetate (5.3%), nerol
(1.7%) and geraniol (7%). Linalyl acetate has been found to readily
rearrange in vitro even when hops are distilled at pH 7. Linalyl
acetate was undetectable in oil obtained by steam distillation of hops
whereas; it can be easily detected in oil distilled by vacuum steam
distillation carried out at room temperature (Pickett et al., 1975b).
Linalyl acetate undergoes thermal degradation during steam
distillation, leading to linalyl, geranyl, and neryl carbocation, which
induces considerable rearrangement reactions (Fig 1). Hydration of
previously formed hydrocarbons yields corresponding alcohols (Morin
& Richard, 1985). In plants containing high proportions of linalyl
acetate, it is not surprising to encounter recemization of linalool
produced during ester thermal degradation in the steam distilled oil
(Casabianca et al., 1998). During hydrodistillation, acidic conditions
(pH=5.5-6.5) promote the decomposition of linalyl acetate and linalool
(Boelens & Sindreu, 1998). For example, linalyl acetate can be
converted by allylic rearrangement into geranyl acetate and neryl
acetate and by elimination into acyclic monoterpene hydrocarbons
such as myrcene, cis- and trans-b-ocimenes (Fig 2). Linalyl acetate
is hydrolyzed in considerable amounts during prolonged steam
distillation and under the same conditions also produces monocyclic
monoterpenes hydrocarbon – terpinolene – as the main product from
linalyl acetate via the a-terpinyl cation and terpinen-4-yl cation (Fig
3). a-Terpineol and then 1,8-cineole can be formed by hydration of
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
125
the a-terpinyl cation. So also terpinene-4-ol can be formed by the
hydration of the terpinene-4-yl cation. Linalool also shows similar
rearrangement and elimination reactions under such conditions. As
mentioned earlier, esters are hydrolyzed to their corresponding
alcohols and carboxylic acid. Hydrolysis is catalyzed by carboxyl
esterases or esterases (Satoh, 1987) (Fig 4).
Conventionally lavender oil is being produced by steam distillation
on commercial scale. However, there is no report which compares
variations in the lavender oil yields and its chemical composition
produced by different methods of hydrodistillation viz., water
distillation, water-steam distillation and steam distillation.
Theoretically, there is no fundamental difference between these three
methods. However, there are certain variations in practice and the
practical results obtained, in some cases have considerable variations
because of above discussed chemical reactions occurring during
distillation and the same are reported in the present investigation.
This paper presents the variations in the qualitative and quantitative
characteristics of the lavender oils by different hydrodistillation
techniques.
MATERIALS AND METHODS
Plant Material
A plantation of L. angustifolia is maintained at Mountain Agriculture
Research and Extension Station, Choudhary Sarvan Kumar Himachal
Pradesh Krishi Vishwavidhyalaya (CSKHPKV), Salooni, district
Chamba, Himachal Pradesh, India. The shoot or flower biomass was
harvested in the month of June 2003 from one year old plantation.
The experimental location experiences a cold-dry climate, at an
altitude of 1800 m above mean sea level (amsl) in the western
Himalayas.
Distillation
Water distillation: Two kg flowering tops (spikes) of L. angustifolia
were charged into the vessel of Clevenger-type apparatus along with
4 l of water to distil by water distillation method. This method
involves distilling the essential oil yielding herbs by keeping the
biomass in direct contact with the water. The spikes were distilled
for 3 h to isolate the essential oil completely. The oil isolated was
measured, dried over anh. Na2SO4, filtered and analyzed.
Water-Steam distillation: The design and operating procedure of
HerboStillTM used for distilling the lavender spikes were described
in earlier communications (Babu et al., 2002, 2004, 2005, 2007; Rawat
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization126
et al., 2007; Babu & Kaul, 2007). Eight kilograms lavender spikes
were charged over a false bottom/perforated grid in the HerboStillTM,
which was adjusted to accommodate 8 l of water at the bottom of the
vessel to distil the spikes by water-steam distillation method. This
method involves, distilling the plant material which was not in direct
contact with the water. A distance of 50 mm was maintained between
the plant charge and the water. The water vapor generated below
the false bottom was always in the form of saturated steam and
never superheated. This saturated steam was used to distil the
plant material. The vessel of the apparatus was heated on liquefied
petroleum gas (LPG) to commence the distillation. The vapors started
forming after 15-20 min., were condensed in a condenser and the
distillate along with oil was collected in a glass receiver. This process
was continued for 3 h. The oil was separated, measured, dried over
anh. Na2SO4, filtered and then used for analysis.
Steam Distillation
Two hundred kg flowering tops of the crop were charged over a
perforated grid (false bottom) in a commercial scale stainless steel
(SS) distillation tank which was connected to a steam boiler. The
herbage was steam distilled by feeding the steam at the bottom of
the false bottom in the tank. The steam, evolved through the plant
material consisting of water and essential oil, was condensed in a
water cooled shell and tube heat exchanger and collected in a
receiver/separator. The excess distillate (hydrosol) collected in the
receiver was removed continuously from the receiver/separator and
the whole process was continued for 4 h. At the end, 1800 mL oil
collected in the receiver was separated.
Gas Chromatography (GC)
GC analysis of essential oil samples was performed on Shimazdu Gas
Chromatograph GC-2010 fitted with BP-20 capillary column (SGE
International, Ringwood, Australia) length 30 m, internal diameter
0.25 mm, film thickness 0.25 mm using nitrogen as auxiliary carrier
gas with flow rate 4 ml/min, equipped with FID. Temperature was
programmed from 40-220oC at 4oC/min, held isothermally at 40 and
220oC for 5 min each. Sample injection volume, 2 µL; injector and
detector temperatures were kept at 220oC and 250oC, respectively.
Gas Chromatography-Mass Spectrometry (GC-MS)
GC-MS (70 eV) data were measured on MS-QP – 2010 series Shimadzu,
Tokyo, Japan equipped with MSD, AOC – 20i auto-sampler and BP-
20 capillary column (SGE International, Ringwood, Australia) 30 m
length, 0.25 mm i.d. and film thickness, 0.25 mm (polyethylene
glycol). The oven temperature was programmed as mentioned in
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
127
GC. MS source temperature, 200oC; interface temperature, 220oC,
injector and detector temperatures, 220oC. Sample injection volume,
2 µl; split ratio, 1:50 and Mass Scan, 40 -600 amu. Helium was used
as a carrier gas with 1.1 mL/min flow rate.
Identification
A mixture of alkanes (C8-C32) was used as reference in calculation of
relative rention indices. Identification of constituents was carried
out with the help of retention indices and by comparison of mass
spectra with the data available in the literature (Adams, 1995;
Jennings & Shibamoto, 1980; MacLafferty, 1989), National Institute
of Standards and Technology (NIST) (Stein, 1990) and our own created
libraries.
RESULTS AND DISCUSSION
Variation in Lavender Oil Yields
Water distillation produced higher oil yield with 1.6% (32 ml from 2
kg) closely followed by water-steam distillation with 1.1% oil yields
(88 mL from 8 kg). However, steam distillation produced lowest oil
yields with 0.9% (1800 mL from 200 kg). This trend was also observed
earlier, in the case of geranium oil production (Babu & Kaul, 2005).
The lower oil yields in the steam distillation may be attributed to
the conditions prevailed during distillation such as lump formation
and agglutination of plant material and not recycling of hydrosol to
recover the dissolved oil, which caused incomplete recovery of the
oil.
Variation in Lavender Oil Composition
The major constituents characterized in the oil were myrcene, 1,8-
cineole, (Z) and (E)-b-ocimene, linalool, linalyl acetate, b-
caryophyllene, lavandulyl acetate, a-terpineol, neryl acetate, geranyl
acetate and geraniol. Lavender oil produced by water distillation
method was found to be richer in linalool (39.74%), a-terpineol (8.01%),
geraniol (2.78%), geranyl acetate (2.16%) and neryl acetate (1.25%).
The oil produced by water-steam distillation method contained higher
percentage of linalyl acetate (47.1%), 1,8-cineole (2.3%), a-pinene
(0.29%), d-3-carene (0.28%), b-pinene (0.2%) and sabinene (0.14%).
The oil produced by the steam distillation method contained higher
amounts of b-caryophyllene (6.27%), (E)-b-ocimene (3.03%), myrcene
(2.03%), (Z)-b-ocimene (2.28%). The composition of oil recovered
from the hydrosol collected during steam distillation was also analysed
and compared with direct oil and reported elsewhere (Babu & Singh,
2007).
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization128
Fig 1. Thermal degradation of linalyl acetate
The highest monoterpene hydrocarbons (10.05%) and
sesquiterpenoids (10.28%) content were observed in the oil obtained
by steam distillation method followed by water-steam distillation
method (6.31% and 7.73%) and water distillation method (5.62% and
3.18%, respectively). This may be attributed to the non-polar nature
of the constituents possessing strong lipophillic bondages with the
fatty (oil) components (Koedam et al., 1979), which require higher
energy to break the bondage (Babu & Kaul, 2007). This energy can
be met by the higher enthalpy of the steam which is generated in a
separate boiler and delivered at a higher pressure in the distillation
tank during steam distillation method. This steam at higher pressure
also easily distills the higher boiling point constituents such as
sesquiterpene hydrocarbons. Hence, the steam distilled oil possessed
the higher monoterpene hydrocarbons and sesquiterpenoids. Contrary
to this, water and water-steam distillation methods produced oils
having lower monoterpene hydrocarbons and sesquiterpenoids, as
the steam generated in the still is always saturated and never be
superheated, which possess lower enthalpies. The highest
monoterpene cyclic ethers were found in the oil produced by water-
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
129
steam distillation method (2.66%) closely followed by water distillation
method (2.29%) and steam distillation method (1.43%). Out of 2.66%
of monoterpene cyclic ethers (in the oil produced by water-steam
distillation method), 1,8-cineole was found to be the major component
(2.3%).
Higher total ester content (50.44%) was also observed in the oil
produced by water-steam distillation method followed by steam
distillation method (41.29%). The lowest total ester content was
observed in the oil produced by water distillation method (35.52%).
The major esters present in all the oil samples produced by these
different hydrodistillation techniques were linalyl, lavandulyl, neryl
and geranyl acetates. Linalyl acetate is one of the most important
ester which determines the quality of oil produced. The oil produced
by water-steam distillation method possessed highest linalyl acetate
(47.1%). The lowest linalyl acetate (30.01%) was found in the oil
produced by water distillation method followed by steam distillation
method (35.28%). On the contrary, neryl acetate and geranyl acetate
were found to be higher in the water distillation method (1.25% and
Fig 2. Rearrangement of linalyl acetate during distillation
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization130
Fig 3. Hydrolysis of linalyl acetate
2.16%) and steam distillation (1.1% and 1.97%) than the water-steam
distillation method (0.51% and 0.8%, respectively). This can be
attributed to the fact that the linalyl acetate under acidic conditions
gets rearranged into neryl and geranyl acetates (Fig 2) (Mastelic,
2000).
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
131
In addition to experiments described above, the spent water
(generally brown in color) discharged from the vessels was tested for
its acidity after completion of the distillation process and showed
pH=5 during water distillation and that of steam distillation tank
has pH=5.5. However, the spent water in the water-steam distillation
tank possessed pH=6.8. This variation in the pH can be correlated
to the extent of these chemical reactions that had taken place during
distillation. The water present in the still during water distillation
method was high as the plant material has to be dipped/immersed
into the water. Although, initially there was no water present in the
tank during steam distillation, as distillation proceeds, steam gets
condensed through heat losses and the level of water content
increases. Higher the water contents in the vessel, higher the
degraded product formation as suggested by the reversible reaction
presented in the introduction part. Hence, the pH of spent water in
water distillation and steam distillation methods possessed higher
acidity (pH is 5 and 5.5, respectively). However, in the case of water-
steam distillation method, the water was kept below the false bottom
and the level was maintained constant through out the process, which
helps in keeping the pH near neutral.
Contrary to the total ester content, the total alcohol content was
found to be the highest in the oil produced by water distillation
method (52.32%). The lowest total alcohol content was observed in
water-steam distillation method (31.88%) followed by steam distillation
method (35.58%). Similar trend was also observed in the distillation
of geranium oils and was due to the hydrolysis of esters discussed
elsewhere (Babu & Kaul, 2005). Therefore, it can be concluded that
the more water content in the distillation tank/vessel, the more
hydrolysis of esters takes place, thereby increasing the total alcohol
content and acidity as the reversible reaction carry forward (towards
right hand-side/product side) until the equilibrium is established.
The products formed during hydrolysis of esters, for example linalyl
Fig 4. Hydrolysis of linalyl acetate by carboxyl esterase
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization132
Table 1. Lavender oil distilled by different hydrodistillation techniques
Compounds RI#Water Water-steam Steam
distillation distillation Distillation
a-Pinene 1011 0.19 0.29 0.16
Camphene 1049 0.20 0.31 0.35
b-Pinene 1114 0.13 0.20 0.14
Sabinene 1123 0.13 0.14 0.12
d-3-Carene 1149 0.19 0.28 0.16
Myrcene 1162 1.10 0.97 2.03
Limonene 1203 0.72 0.92 1.10
1,8-Cineole 1211 1.83 2.30 1.43
(Z)-b-Ocimene 1235 1.12 1.39 2.28
(E)-b-Oci mene 1252 1.47 1.50 3.03
p-Cymene 1269 0.14 0.17 0.30
a-Terpinolene 1283 0.23 0.14 0.38
1-Octen-3-yl acetate 1383 0.73 0.67 0.90
cis-Linalool oxide 1444 0.28 0.20 —
trans-Linalool oxide 1472 0.18 0.16 —
Camphor 1509 0.26 0.25 0.23
Linalool 1557 39.74 26.06 28.78
Linalyl acetate 1564 30.01 47.10 35.28
a-Santalene 1567 — — 0.74
Bornyl acetate 1578 0.24 0.14 0.24
a-trans-Bergamotene 1584 — 0.16 0.25
b-Caryophyllene 1590 1.27 5.30 6.27
Terpinen-4-ol 1602 0.79 0.72 0.53
Lavandulyl acetate 1611 1.13 1.22 1.80
a-Humulene 1659 — 0.19 0.27
(E)-a-Farnesene 1666 1.02 1.38 1.64
Lavandulol 1682 — 0.42 0.47
a-Terpineol 1699 8.01 3.55 3.78
Neryl acetate 1730 1.25 0.51 1.10
ã-Cadinene 1747 — 0.13 0.19
Geranyl acetate 1760 2.16 0.80 1.97
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
133
acetate, can be divided into two categories (i) oxygenated
monoterpenes and (ii) non-oxygenated monoterpenes. The oxygenated
monoterpenes for example 1,8-cineole, a-terpineol and terpinene-4-ol
are formed by hydration of the a-terpinyl cation and terpinene-4-yl
cation. Similarly, the non-oxygenated monoterpenes viz., terpinolene,
limonene and a-terpinene were formed through the same cations
(intermediates) but by eliminating the proton (Fig 3). Linalool also
shows similar reactions of rearrangement and elimination under the
same conditions as well (Mastelic et al., 2000). Therefore, linalool
by allylic rearrangement gives rise to geraniol and/or nerol and so
on.
Therefore, depending upon the conditions prevailed in the
distillation tanks, the reactions progressed and different products of
varying quantities were formed. For example, neryl acetate (0.51%)
and geranyl acetates (0.8%) were found minimum in the water-steam
distillation and maximum content was found in water distillation
(1.25% and 2.16%, respectively). This excess amount of neryl and
geranyl acetates might have formed by the allylic rearrangement of
linalyl acetate (Fig 2). Hence, the conditions prevailing during water
Nerol 1805 1.00 0.29 0.56
Geraniol 1854 2.78 0.82 1.46
Caryophyllene oxide 1971 0.61 0.44 0.69
ô-Cadinol 2169 0.28 0.13 0.23
Total 99.19 99.25 98.86
Monoterpene 5.62 6.31 10.05
hydrocarbons
Monoterpene cyclic 2.29 2.66 1.43
ethers
Carbonyls 0.26 0.25 0.23
Esters 35.52 50.44 41.29
Alcohols 52.32 31.86 35.58
Sesquiterpenoids 3.18 7.73 10.28
Oil yields (%) 1.60 1.1 0.90
#RI = retention indices on BP-20 column; —, absent
Table 1. Contd.
Compounds RI#Water Water-steam Steam
distillation distillation Distillation
Comp. of Bio. Nat. Pro., Vol. 8 – Quality Control & Standardization134
distillation favored the formation of neryl and geranyl acetates.
Similarly, allylic rearrangement of linalool also more favored in water
distillation and steam distillation as higher nerol (1% and 0.56%,
respectively) and geraniol (2.78% and 1.46%, respectively) contents
were found than in the water-steam distillation (0.29% and 0.82%,
respectively). Similarly, elimination (of CH3COOH or CH3COO– from
linalyl acetate and OH or O– from linalool) reactions were also favored
in water distillation and steam distillation as the formation of
myrcene, a-terpinolene and a-terpineol were found in higher
concentration than in the oil produced by water–steam distillation.
The formation of acyclic monoterpene hydrocarbons viz., (Z) and (E)-
b-ocimene (2.28% and 3.03%, respectively) were very high in steam
distillation method whereas the conditions might not be favorable in
water distillation as they are in lower quantities (1.12% and 1.47%,
respectively). Similar trends were also observed in the case of
limonene. The formation of linalool from linalyl acetate is higher in
the water distillation method than in the water-stream distillation.
Hence, the oil produced by water distillation method contained higher
amount of linalool (39.74%) and lower content of linalyl acetate
(30.01%) in contrary to the higher content of linalyl acetate (47.1%)
and lower content of linalool (26.06%) in the water-steam distillation
method.
CONCLUSIONS
It is well-known that conventionally the lavender oil is steam distilled
on commercial scale. However, the present experimental findings
reveal that water-steam distillation method produced higher yields
and better quality lavender oil in terms of higher ester content than
the steam distillation method. In general, the by-products content
formed by different chemical reactions were higher in water distillation
and lower in water-steam distillation method followed by steam
distillation method. Therefore, it is recommended that the lavender
oil, on commercial scale, may be produced preferably by water-steam
distillation method to reduce the by-product formation by various
chemical reactions and to get better oil yields. Furthermore, the
production cost can be reduced as water-steam distillation doesn’t
require steam generator, skilled operator, small space for unit
installation etc.
ACKNOWLEDGEMENTS
The authors are grateful to the Director, IHBT Palampur for
continuous encouragement and for providing necessary facilities
during the course of this investigation. The authors also gratefully
Characteristics Variation of Lavender Oil produced by Different
Hydrodistillation Techniques
135
acknowledge the funding of this project by 11th International Congress
of Essential Oils Fragrances and Flavors-1989 (ICEOFF-89), New
Delhi. Thanks are also due to Mrs. Vijaylata Pathania for providing
chromatograms and Mr. Gian Chand for technical support services.
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