Vetiver Oil Valorization
J. Agric. Food Chem., Vol. 52, No. 21, 2004 6579
(13), and even on lemongrass and lemon eucalyptus (14). As
in every vegetal organism, the vetiver root cells are protected
by a thick wall composed of cellulose and pectin, which may
be an obstacle to the extraction. The use of enzymes to act over
the cell walls has been tested as a previous step of the oil
extraction.
The use of supercritical fluid extraction (SFE) to obtain
vegetable extracts can be of great interest to improve the quality
of the product, since it is a clean technology, which does not
employ organic solvents that may be toxic. Another potential
advantage of SFE is that high-process temperatures are not
required as in steam distillation, so that the thermal modifications
in the chemical composition of the extract may be avoided. SFE
has been studied as an extraction method of many products from
vegetable sources, which are of interest in food and pharma-
ceutical industries, like ginger (15). Carbon dioxide is an
appropriate solvent to these kinds of products because of its
low viscosity if compared to liquids and high solubility power
compared to gases at near critical or supercritical conditions.
The objective of this work was to evaluate different methods
of oil extraction from Brazilian vetiver roots. This evaluation
took in account the extraction yields and the quality of the
products. The performed extraction methods were hydrodistil-
lation with or without pretreatment and SFE. The extracts
obtained with each method from roots collected in Brazil as
well as commercial vetiver oils from different sources were
chemically analyzed and the chemical composition was related
to their sensorial properties. Some chemical reactions were also
performed on the acid fraction isolated from the Brazilian vetiver
oil, as a trial to improve its quality and acceptability to the
market.
Figure 1. Flow chart of the pretreatments of vetiver roots before
hydrodistillation.
the optimal condition for these enzymes (12). Fifty grams of vetiver
roots were mixed into the solution. The system was shaken for 8 h at
room temperature and was kept without shaking for another 16 h before
the distillation.
Combined Treatment. A combined pretreatment of NaOH and
enzymes was also performed: the roots were treated with NaOH as
described previously; after 8 h under stirring and 16 h without stirring,
the solution was re-acidified with acetic acid until pH 4.5. Then, the
enzymatic treatment was performed as already described.
Extraction Procedures. Hydrodistillation. A 50-g fraction of vetiver
roots was hydrodistilled using a Clevenger type apparatus. The roots
were put into a 2-L flask with 1 L of distilled water. Two milliliters of
hexane were introduced in the decantation part of the Clevenger
apparatus to dissolve the volatile oil during the 16 h of the extraction
process. The oil phase was periodically collected and the hexane was
evaporated so that the amount of oil could be evaluated in function of
the distillation time.
Supercritical Fluid Extraction (SFE). An experimental design of two
factors (temperature and pressure) and two levels (30 and 40 °C, 80
and 200 bar) was performed to define the conditions in which the
highest yield in extract was achieved. Because the extraction was
exhaustive for these experiments, the extraction time used was 2 h.
The conditions that provided the highest yield were 40 °C and 200
bar, so this temperature and pressure were used for all SFE experiments.
Thirty grams of vetiver roots were used in each SFE experiment, with
a CO2 flow rate of 6.9 × 10-5 kg/s, during 1 h. The SFE unit used was
built in the Technical University of Hamburg-Harburg (TUHH,
Hamburg, Germany) (16). The CO2 at the required conditions was
pumped into the line, entering in contact with the vetiver roots
compacted in a 100-mL stainless steel column. The mixture of CO2
and extract had its pressure decreased in the outlet valve, so the extract
could be collected in a flask cooled with ethylene glycol and then
weighed. A micrometer valve was used to control the CO2 flow rate
that was measured in a calibrated rotameter. The extraction yield was
measured as the ratio between mass of extract and dried raw material.
The extract was separated from the solvent through expansion in
the micrometer valve by reducing the pressure to ambient. Some
samples of SFE extract were submitted to a hydrodistillation process
at the conditions previously described to get the ratio between volatile
and nonvolatile components and to determine the chemical composition
of the volatile fraction.
MATERIALS AND METHODS
Materials. Vetiver roots were purchased from a local producer in
the state of Sa˜o Paulo, Southeastern Brazil. Some commercial samples
of vetiver oil were studied for comparison purposes: volatile oil of
vetiver variety Haiti (Charabot, Lot 0000079172, Grasse, France),
volatile oil of vetiver variety Java (Charabot, Lot 0015430002, Grasse,
France), volatile oil of vetiver variety Bourbon (personal sample), and
volatile oil of Brazilian vetiver from the same supplier of the roots.
Preparation of Raw Material. Vetiver roots were dried in an air-
conditioned room for 48 h and milled in a knife mill (Tecnal TE-631,
Piracicaba, Brazil) before every performed extraction procedure. The
particles of milled roots were separated according to their particle size
in a vibratory sieve system (Series Tyler, W. S. Tyler, Wheeling, IL).
The particles with mean diameter of 8.6 × 10-4 m were selected for
the extraction procedures and stored in a domestic freezer at -18 °C.
In some cases, before the hydrodistillation process itself, the vetiver
roots were submitted to some pretreatments, with the objective of
improving the contact between the oil and the extraction medium. The
process from pretreatments to hydrodistillation and SFE is shown
schematically in Figure 1. The performed pretreatments before hy-
drodistillation were the following:
Milling in Liquid Nitrogen. The roots were cryomilled in liquid
nitrogen with a Dangoumill 300 freezer-mill (Prolabo, Paris, France)
for 3 min (top impact frequency). The milled roots were stored at -20
°C.
Treatment with Sodium Hydroxide. Fifty grams of vetiver roots were
immerged into 1 L of a 1 M NaOH solution. The mixture was first
kept 8 h under stirring. After that, it was kept without stirring for another
16 h. Then, it was re-acidified with acetic acid until its original pH,
which was 4.5, before starting the distillation process.
Chemical Composition of Vetiver Oil. The extracted samples from
Brazilian vetiver roots, as well as commercial oil samples from varieties
Haiti, Java, Bourbon, and Brazil were analyzed by gas chromatography
(GC) and GC-mass spectrometry.
Gas Chromatography. GC analyses were performed on a Varian
gas chromatograph, model CP-3380, equipped with flame ionization
detector containing two silica capillary columns: CP Sil 5 CB low
bleed/MS (100% dimethyl polysiloxane, Chrompack/Varian, Palo Alto,
Enzymatic Treatment. For the enzymatic treatment of vetiver roots,
two commercial enzymes were used: Celluclast (Lot CCN 3017, Novo-
Nordisk, Denmark) and Pectinex Ultra SP-L (Lot KRN 05401,
Dittingen, Switzerland). Twenty microliters of each enzyme solution
was dissolved into 1 L of an acetic acid solution of pH 4.5, which is