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ORIGINAL PAPER
Characterization of Aromatherapy Massage Oils Prepared
from Virgin Coconut Oil and Some Essential Oils
Sarunyoo Songkro ÆAnusak Sirikatitham ÆSupreedee Sungkarak Æ
Khemmarat Buaking ÆJuraithip Wungsintaweekul Æ
Duangkhae Maneenuan ÆKwunchit Oungbho
Received: 31 March 2009 / Revised: 16 July 2009 / Accepted: 9 August 2009
ÓAOCS 2009
Abstract The aim of this study was to characterize aroma-
therapy massage oils prepared from virgin coconut oil
(VCO) and some essential oils. VCO extracted from fresh
coconut endosperm by a centrifugation method, which was
the most effective method to prepare VCO, was composed
mainly of saturated fatty acids, in particular myristic acid.
Three essential oils (lemon, eucalyptus and lavender oils)
at concentrations of 1, 3 and 5% w/w were blended with
the VCO to prepare massage oils. Physical and chemical
properties as well as microbial analysis of the massage oils
were assessed to evaluate quality characteristics of the
preparations. Results showed that types and concentrations
of essential oils used somewhat affected viscosity, refrac-
tive index and three chemical characteristics (acid, per-
oxide, and iodine values) associated with oxidative stability
of the massage oils. Generally the rank order of acid,
peroxide and iodine values of the freshly prepared massage
oils appeared to be lemon oil [lavender oil [eucalyptus
oil. The results of a accelerated storage stability study
(45 °C, 4 months) clearly showed a dramatic increase in
both acid and peroxide values of VCO and the blended
massage oils compared to initial values, whereas the iodine
values of these preparations decreased slightly. The plain
VCO and the blended massage oils did not exhibit anti-
microbial activity on the test microorganisms and were free
from microbial contamination.
Keywords Virgin coconut oil Lemon oil
Eucalyptus oil Lavender oil Essential oil Acid value
Peroxide value Iodine value Refractive index
Viscosity
Introduction
Coconut, Cocos nucifera L. (Arecaceae) [1], is a typical
palm distributed over most of the islands and coasts of the
tropical regions of the world [2]. Coconut palm is one of the
major economic crops in Thailand. It produces an ovoid
fruit consisting of husk (35%), shell (28%), meat (endo-
sperm) (28%) and water (15%) [3]. It is generally recog-
nized that the coconut provides many items of great value to
man, such as a source of coconut meat, juice, milk and oil.
In traditional folklore medicines of many cultures, coconut
has been used to treat several health problems, including
intestinal worm infections, skin diseases or lesions (rashes,
cuts, injuries, and swellings), gastrointestinal diseases (e.g.
diarrhea) [4–6]. Currently, there is a great deal of research
and commercial interest in coconut products including
coconut protein isolate, coconut skim milk, coconut flour
S. Songkro S. Sungkarak K. Buaking D. Maneenuan
K. Oungbho (&)
Department of Pharmaceutical Technology,
Faculty of Pharmaceutical Sciences,
Prince of Songkla University, Songkhla 90112, Thailand
e-mail: kwunchit.o@psu.ac.th
A. Sirikatitham
Department of Pharmaceutical Chemistry,
Faculty of Pharmaceutical Sciences,
Prince of Songkla University, Songkhla 90112, Thailand
J. Wungsintaweekul
Department of Pharmacognosy and Pharmaceutical Botany,
Faculty of Pharmaceutical Sciences, Prince of Songkla
University, Songkhla 90112, Thailand
S. Songkro A. Sirikatitham S. Sungkarak K. Buaking
J. Wungsintaweekul D. Maneenuan K. Oungbho
Drug Delivery System Excellence Center,
Prince of Songkla University, Hat Yai,
Songkhla 90112, Thailand
123
J Am Oil Chem Soc
DOI 10.1007/s11746-009-1465-5
and coconut oil, and the latter, especially virgin coconut oil
(VCO), has gained a lot of attention.
Coconut oil can be extracted from coconut meat using
two different processes, namely the dry and the wet pro-
cesses. In the dry process, the coconut meat is dried first by
exposing to sunlight or very high temperatures for several
days. However, upon exposure to sunlight and high tem-
perature, the bioactive components (e.g. tocopherols and
polyphenols) may be inactivated. The unrefined oil is
extracted from the copra (dried coconut meat) by expres-
sion or prepress solvent-extraction methods [4]. Before
consumption, the coconut oil needs to go through refining,
bleaching and deodorization processes [7]. In the wet
process, the oil is extracted from fresh coconut meat under
mild temperature [4], resulting in the production of VCO,
which retains more biologically active components.
Coconut oil has many applications. For example, a large
percentage of coconut oil is used for edible proposes, such
as in cooking (especially frying) and making margarine. It
is a source of medium chain triglycerides which can be
used as nutritional supplement for patients with mal-
absorption [8]. Coconut oil is used for the manufacture of
chemical feedstocks, synthetic detergents, soaps and cos-
metics [9,10]. To reduce the use of mineral oils which can
cause environmental damage, coconut oil has been selected
as an alternative base oil for industrial lubricants [11]. In
addition, the need for odorous essential oils in aromather-
apy has led to a remarkable growth in the use of botanical
ingredients including VCO.
In view of the ever expanding use of aromatherapy as a
complimentary therapy, the development of safe, effective
and high quality natural aromatherapy products is of great
interest. One of the aromatherapy products commercially
available is aromatherapy massage oil. The main ingredi-
ents of the massage oil are carrier oil(s) and essential oil(s)
[12]. Carrier oils, also known as base oils or vegetable oils,
are used to dilute essential oils prior to skin application to
carry the essential oils into the skin. Among the different
vegetable oils, VCO has shown high potential as carrier oil
for aromatherapy [13]. Despite its widespread use, little
scientific data about the characteristics of VCO as aroma-
therapy carrier oil have been published. The characteriza-
tion of VCO and some of its aromatherapy massage oil
products, therefore, was a major aim of this study. Initially,
a small batch of VCO (starting with 100 mL of coconut
milk) was prepared using three different methods, namely
fermentation, refrigeration and centrifugation. The most
suitable method was selected to produce a large scale
production. Certain physical, chemical and microbiological
properties of the preparations were measured to ascertain
their quality characteristics. In this investigation, VCO was
blended with three selected essential oils (lemon, euca-
lyptus and lavender oils) to produce the massage oil
formulations. Effects of types and concentrations of
essential oils on the aforementioned properties and accel-
erated stability study of the VCO and blended massage oils
were also evaluated.
Materials and Methods
Materials
All the mature coconuts (12–14 months) used in the cur-
rent study were obtained from the same healthy coconut
plantation cultivated in Songkhla Province, Thailand. The
coconuts were chosen with care and only those which had
the same stage of maturity were used. Staphylococcus
aureus ATCC 25923, Escherichia coli ATCC 25922,
Pseudomonas aeruginosa ATCC 27853 were obtained
from the American Type Culture Collection. Bacillus
subtilis (clinical isolate) and Candida albicans (clinical
isolate) were kindly provided by Songklanagarind Hospi-
tal, Songkhla, Thailand. Phenolphthalein Test Solution
(TS) used for determination of acid and saponification
values was from ScienceLab (TX, USA). Potassium
hydroxide, hydrochloric acid and methanol were from JT
Baker Inc. (NJ, USA). Alcohol, petroleum ether and
chloroform were purchased from BDH Laboratory Sup-
plies (Poole, UK). Iodobromide TS, potassium iodide TS,
starch TS and sodium thiosulfate Volumetric Solution (VS)
used for determination of iodine values were supplied by
ScienceLab (TX, USA). Lemon oil (B.P.) (Citrus limon,
L.), eucalyptus oil (B.P.) (Eucalyptus globulus, Labill.) and
lavender oil (B.P.) (Lavandula vera, DC.) were purchased
from Srichand United Dispensary Co., Ltd (distributor),
Bangkok, Thailand. Karl Fisher reagent was obtained from
Riedel-de Hae
¨n (Seelze, Germany).Gentamycin and
ketoconazole were supplied by Fluka (Buchs, Switzerland).
a-Tocopherol (97%) was obtained from Sigma-Aldrich
Chemical Company, Inc. (MO, USA). Soybean–Casein
Digest Medium and Mueller Hinton agar were supplied by
Merck (Darmstadt, Germany). Sabouraud’s dextrose agar
was obtained from Difco (KS, USA). Sodium dihydrogen
orthophosphate dihydrate, disodium hydrogen orthophos-
phate anhydrous and sodium chloride used to prepare
phosphate buffer saline pH 7.2 (0.1 M) were purchased
from Univar (NSW, Australia). All chemicals and solvents
were pharmaceutical grade or analytical grade.
Methods
Preparation of Coconut Milk
The coconuts were opened within 24 h after harvesting.
To obtain the fresh squeezed coconut milk (milky white
J Am Oil Chem Soc
123
oil-in-water emulsion), the fresh endosperm of the mature
coconut was grated and pressed using an electric grater and
a mechanical press, respectively. This process was per-
formed without addition of water.
Preparation of Virgin Coconut Oil
To separate oil from water in the coconut milk, the coconut
milk was processed using three different procedures
including fermentation, refrigeration and centrifugation.
This study was conducted in small scale batches to deter-
mine the optimum extraction method for VCO production.
The study was also performed to investigate the suitable
conditions (i.e. fermentation temperature, cooling period)
for the VCO preparation. The most suitable method which
gave the highest yield of VCO was selected to prepare a
pilot scale preparation.
Fermentation A sample (100 mL) of fresh coconut milk
was fermented at different fermentation temperatures (30,
45 and 60 °C) for 24–30 h. After the fermentation, the two
layers were formed, a kind of cream at the top and the
watery layer underneath. The volume of the cream phase
was measured and the cream was further separated from
the water phase. The cream obtained was kept at room
temperature for 2–3 days. After that, the VCO was sepa-
rated from any residues by decantation. Then, the volume
of the resulting VCO was measured.
Refrigeration A sample (100 mL) of fresh coconut milk
was cooled at 4 °C for 2, 4, 6, 8 and 24 h in order to
separate it into two phases; an upper cream phase and a
lower watery phase. The volume of the cream phase was
determined and the cream was further separated from the
water phase. The cream obtained was subjected to mild
heating (50 °C) in a thermostat oven for 1, 2, 4, 6 and 24 h.
Then, the VCO was separated from any residues by
decantation. The volume of the resulting VCO was
measured.
Centrifugation A sample (100 mL) of fresh coconut milk
was cooled to 4 °C for 0, 0.5, 1, 1.5, 2 and 4 h. After
the cooling process, the sample was centrifuged (Sorvall
RC-5B Plus refrigerated centrifuge, Pegasus Scientific Inc.,
USA) at 9,000 rpm at 10 °C for 5 min resulting in the
formation of two layers; a creamy layer at the top, and a
watery layer underneath. After separation from the water
phase, the oily layer obtained was subjected to mild heating
(50 °C) for 15 min and subsequently centrifuged at
9,000 rpm at 25 °C for 5 min to obtain VCO. Next, the
VCO was decanted from the residues at the bottom of
the centrifuge tube. The measurement of the coconut oil
volume was carried out.
Chemical Characteristics of Virgin Coconut Oil
Determination of Acid, Saponification, Iodine and Peroxide
Values Acid, saponification, iodine and peroxide values
of the VCO obtained (small scale batch) were analyzed
chemically according to the official protocols described in
the section of Fats and Fixed Oils of USP 26 and NF21
[14].
Determination of Ester Value The ester value is the
number of mg of potassium hydroxide that is required to
saponify the esters in 1.0 g of the substance. The ester
value is a measure of the combined acids present in the
substance. It is determined by subtraction of the acid value
from the saponification value.
Determination of Fatty Acid Composition The fatty acid
determination of the VCO (small scale batch) was divided
into two steps: the first step was preparation of fatty acid
methyl esters and the second step was GC-MS analysis.
Preparation of Fatty Acid Methyl Ester The preparation
of fatty acid methyl ester was carried out according to the
published guideline by Jham et al. [15]. A 50 lL sample of
VCO was hydrolyzed with 1 mL of 0.5 M potassium
hydroxide in methanol at 100 °C for 5 min in screw-cap
test tubes. Then, the hydrolysis mixture was esterified with
400 lL of hydrochloric acid in methanol (4:1 v/v). The
mixture was heated in an oil bath at 100 °C for 15 min and
allowed to cool to room temperature. After which 2 mL of
distilled water was added and the mixture was extracted
with 2 93 mL of petroleum ether. The upper layer
(petroleum ether) was dried over anhydrous sodium sulfate
and evaporated. Finally, the obtained fatty acid methyl
ester was dissolved in 500 lL of chloroform and further
analyzed by Gas Chromatography–Mass Spectrometry
(GC–MS).
Gas Chromatography–Mass Spectrometry Analysis A
GC-MS was performed on a Hewlett-Packard gas chro-
matograph (HP model 5890 Series, Palo Alto, USA)
equipped with HP 5972 Mass Selective detector; an elec-
tron ionization was used. An aliquot of the test solution
(1.0 lL) was injected into the fused silica capillary column
Stabilwax (30 m 90.25 mm i.d., 0.25 lm film thickness,
Restek, Bellefonte, PA, USA). The injection port temper-
ature was maintained at 225 °C. The transferline temper-
ature was 240 °C. Carrier gas was helium with a flow rate
of 1.0 mL/min. The column oven temperature was pro-
grammed as follows: 100 °C (4 min), 100–240 °C(3°C/
min), 240 °C (10 min).
The components were identified by matching their mass
spectral data with the Wiley 275.L Mass Spectra Database
J Am Oil Chem Soc
123
Library. The percentage compositions of fatty acids were
computed from GC peak areas and calculated as a per-
centage of the total.
Determination of Water Content Of Virgin Coconut Oil
The water content in the VCO was measured by a Karl-
Fisher titrator (Mettler DL 18, Mettler, Switzerland). Karl-
Fisher reagent was standardized with sodium tartrate
dihydrate. A sample of 1.0 mL of VCO was dissolved in a
solvent mixture (1:1 v/v anhydrous methanol-chloroform)
and was then titrated with the standardized Karl-Fisher
reagent.
Pilot Scale Production of VCO
The centrifugation method was selected to prepare a pilot
scale production of VCO, since it provided the highest
yield of VCO. Samples (1.5, 3.5 and 6.5 L) of fresh
coconut milk were cooled to 4 °C for 2 h. After the cooling
process, the sample was centrifuged at 9,000 rpm at 10 °C
for 10 min resulting in the formation of two layers; a
creamy layer at the top, and a watery layer underneath.
After separation from the water phase, the creamy layer
obtained was subjected to mild heating (50 °C) until the oil
was separated and subsequently centrifuged at 9,000 rpm
at 25 °C for 10 min to obtain VCO. The VCO was then
decanted from the residues at the bottom of the centrifuge
tube.
Water content, refractive index and viscosity of VCO
from each batch were determined. To prepare aromather-
apy massage oils, VCO from all three batches were blended
together and stored in air-tight light resistant containers at
room temperature.
Preparation of Aromatherapy Massage Oils
In the current study, the carrier oil was the VCO and the
selected essential oils were lemon, eucalyptus and lavender
oils at three different concentrations, 1, 3 and 5% w/w. The
antioxidant used in the current study was a-tocopherol
(0.5% w/w). The VCO and the essential oil with or without
the antioxidant were mixed together and stored in air-tight-
light resistant containers at room temperature. Three
samples of each formulation type were prepared. The
containers were best kept as full as possible in order to
exclude the action of air.
Physical Characteristics of Massage Oils
Viscosity Measurement The viscosity of freshly prepared
massage oils and VCO was measured with a Brookfield
bob-cup viscometer (LV type, Brookfield, UK) at 30 rpm at
room temperature (32 ±1°C). The formulation was placed
in the sample cup and allowed to stand until it reached room
temperature before the viscosity was measured. The vis-
cosity measurement of the test materials was performed
again after 6-month storage at room temperature.
Refractive Index Measurement The refractive indices of
freshly prepared massage oils and the VCO were deter-
mined with a Refractometer (ABBE ‘60’ Refractometer,
Bellingham & Stanley Ltd, UK) at room temperature
(32 ±1°C). The refractive index of the test materials
was determined again after 6 months of storage at room
temperature.
Chemical Characteristics of Massage Oils
The chemical properties of the massage oils and the VCO
were determined by measurement of three important indi-
cators associated with oxidation and rancidity, namely acid
value, peroxide value and iodine value. The details of the
experiments are described in the section of Fats and Fixed
Oils of USP 26 and NF21 [14].
Storage Stability Study
The stability of VCO and blended massage oils was
determined by storing the samples of VCO and massage
oils under accelerated temperature (45 °C), 70–75% R.H.
for 4 months. Three samples of each formulation (40 g)
were placed into well-filled air tight glass bottle and pro-
tected from light. The level of oxidative deterioration was
investigated by measurement of the acid, iodine and per-
oxide values. Determination of these three indicators was
carried out according to the official methods of the USP 26
and NF21 [14].
Antimicrobial Assay
The test bacteria used in this study were Staphylococcus
aureus ATCC 25923 (gram?), Escherichia coli ATCC
25922 (gram-), Pseudomonas aeruginosa ATCC 27853
(gram-) and Bacillus subtilis (gram?), and the fungus
used was Candida albicans. All strains, except Candida
albicans, were cultured on Mueller Hinton agar (MHA) at
35–37 °C for 24 h. Candida albicans was cultured on
Sabouraud’s dextrose agar (SDA) at 35–37 °C for 24–48 h.
Sterile normal saline was added to the slant and the sus-
pension was transfer to a sterile tube. Then, the turbidity of
the resulting suspension was adjusted to 25% transmittance
at 540 nm with sterile normal saline.
The susceptibility of the microbial to the test materials
(massage oils containing 5% w/w essential oils and VCO)
was determined using the well-diffusion method as
J Am Oil Chem Soc
123
described by Shadomy et al. [16] with minor modifications.
A sterile cotton swab was dipped in the inoculum (sus-
pension) and the excess was removed by rotating the swab
several times against the inside wall of the tube above the
fluid level. The surface of MHA or SDA plates was inoc-
ulated with bacteria or fungus by streaking the swab over
the surface. Streaking was repeated 3 times. After each
time, the plate was rotated by 60°. In each of these plates,
six wells were cut out using a sterile cork border (5 mm
diameter). The space between each well was 15–20 mm and
the space between the well and the edge of the plate was at
least 15 mm. Solutions of the test substances (100 lL) were
carefully filled into each well and the plates were then
incubated at 35–37 °C for 16–18 h. The positive controls
were gentamicin and ketoconazole. In addition, three pure
essential oils were used as reference compounds and posi-
tive controls. The antimicrobial activity was evaluated by
measuring the diameter of inhibition zone (clear zone). The
inhibition zones were recorded at 16–18 h after incubation
at 35–37 °C. Three samples of each formulation were tested
for their antimicrobial activity. The antimicrobial assay was
carried out with freshly prepared formulations and with
formulations stored at room temperature for 6 months.
Microbial Count
The microbial count of VCO and the massage oil formu-
lations containing 5% w/w essential oils was determined.
Total Aerobic Bacteria Count The total aerobic bacteria
count was performed following standard procedures as
described in USP 26 & NF21 [14]. The test was carried out
by mixing 5 mL of the test material with 95 mL of phos-
phate buffer saline pH 7.2, which resulted in a 10
-1
dilu-
tion. Ten-fold serial dilutions were made in the same
dilution to a 10
-6
dilution. This gave the number of col-
onies from 30 to 300 colonies per plate. Subsequently,
1 mL of each dilution was pipetted into the plate, using two
plates for each dilution. After that, 15–20 mL of Soybean-
Casein Digest Medium (50 °C) was poured into the plate.
The dilutions and the culture medium were mixed together
and allowed to solidify. Plates were inverted and incubated
at 35–37 °C for 24–48 h. After the incubation, the number
of colonies was recorded for each plate. Arithmetic mean
counts were obtained from each item having from 30 to
300 colonies per plate. Three samples of each formulation
were tested for their total aerobic bacteria count. The test
was carried out with freshly prepared formulations and
with stored formulations at room temperature for 6 months.
Total Mold and Yeast Count The total mold and yeast
count was determined using standard procedures as
described in the USP 26 & NF21 [14]. The experiment was
performed in the same way as previously described in the
total aerobic bacterial count. However, SDA was used as
the culture medium and the plates were incubated at 20–
25 °C for 5–7 days. Three samples of each formulation
were tested for their total mold and yeast count. The test
was carried out with freshly prepared formulations and
with formulations stored at room temperature for 6 months.
Statistical Analysis
Results were expressed as means ±standard deviation
(SD). Statistical analysis (paired ttest, Student’s ttest,
One-way ANOVA) was determined using Minitab release
version 14 (Minitab Inc., State College, USA). Differences
at p\0.05 were considered to be significant.
Results and Discussion
Preparation of Virgin Coconut Oil (Small Scale Batch)
In the current study, the VCO was obtained from fresh
coconut meat since it has been reported that the coconut oil
produced from dried copra is often of poor quality [4]. Fur-
thermore, there are losses of the oil caused by microbial
spoilage and insects during the drying or storage stages.
Losses also occur due to incomplete oil recovery from the
copra cake [4]. The use of the wet milling process should
result in a better quality of coconut oil and the quantitative
recovery of the oil should be increased. Three methods
namely, fermentation, refrigeration and centrifugation were
employed in order to investigate the suitable method for the
oil extraction. At this stage, only a small amount of the
coconut milk (100 mL) was used. In the case of the fer-
mentation process, it was observed that at the experimental
temperatures, the coconut milk separated into two layers
which were a cream phase (the oil-rich phase) and a water
phase. Only the cream phase was collected and kept at room
temperature for 3 days. After the storage period, it was found
that the cream had further separated into four fractions. From
top to bottom, the fractions were free oil, cream, water and
sediment products. The VCO obtained was clear and color-
less. As seen from Table 1, the fermentation temperature of
45 °C gave the highest amount of the oil when compared to
the other two fermentation temperatures, 30 and 60 °C
(p\0.05, ANOVA). Moreover, at 45 °C, the coconut oil
had a very pleasant odor.
Using the refrigeration process to prepare the coconut
oil was not successful in this study. When the coconut milk
was cooled at 4 °C with different cooling periods from 2 to
24 h, only a small amount of water was separated. More-
over, the coconut oil was not separated after the cream
phase was heated at 50 °C for 1–24 hours.
J Am Oil Chem Soc
123
In the centrifugation method, it was observed that the
coconut milk was separated into two layers after centrifu-
gation at 10 °C from 0 to 4 h. These layers were cream
phase and water phase which contained sediment products.
Only the cream phase was collected and subjected to mild
heating at 50 °C until the oil was separated. After a further
centrifugation at 25 °C for 5 min, four fractions were
observed: free oil, cream, water and sediment products.
The VCO was separated from the other three unwanted
layers by decantation. The cooling period seemed to affect
the yield of VCO. It was found that the cooling period of
2 h tended to give the highest amount of VCO production
(Table 2). The VCO obtained was clear and colorless with
a faint odor of coconut. The VCO was stored in well-filled,
air-tight glass containers and protected from light during
storage.
Chemical Properties of Virgin Coconut Oil
Obtained by Small Scale Production
Fatty acid compositions of VCO prepared by fermentation
and centrifugation methods are given in Table 3. Accord-
ing to GC-MS analysis, the medium chain fatty acids with
12 to 18 carbon atoms were found in the VCO. Unlike
other studies [3,17,18], no short chain fractions (caprylic
and capric acids) were detected in the VCO prepared in this
study. It was found that the VCO contained only small
amounts of unsaturated fatty acids, octadecanoic acid and
linoleic acid. Most of the fatty acids in the VCO were
saturated indicating that the oil had excellent resistance to
oxidative rancidity. With GC-MS library identification, the
major fatty acids in the VCO prepared by both methods
were myristic acid (35–38%), lauric acid (22–30%) and
palmitic acid (23–24%). It was noted that the content of
lauric acid in this study was lower than that reported in the
published literature, which was about 50% [3,17–19]. This
variation is probably due to the differences in soil types,
weather conditions, geological location and extraction
method. Lauric acid has been reported to have antiviral,
antibacterial, anticaries, antiplaque and antiprotozoal
properties [20–22].
Table 1 Effect of fermentation temperature on the yield of virgin
coconut oil (VCO) (mean ±SD, n=6)
Temperature (°C) Yield of virgin coconut oil
(mL/100 mL of coconut milk)
30 10.25 ±0.88
45 18.17 ±0.98
60 12.00 ±1.90
nnumber of sample
Table 2 Effect of cooling period on the yield of virgin coconut oil
prepared by centrifugation method (means ±SD, n=6)
Cooling period (h) Yield of virgin coconut oil
(mL/100 mL of coconut milk)
0.0 15.83 ±1.60
0.5 25.00 ±1.41
1.0 24.67 ±1.97
1.5 28.00 ±0.89
2.0 29.83 ±0.47
4.0 27.00 ±1.41
nnumber of sample
Table 3 Fatty acid constitutions and water content of virgin coconut oil prepared by fermentation and centrifugation methods
Method Fatty acid in virgin
coconut oil
Retention
time (min)
Ratio of fatty
acid (%)
Water content
(% w/v; mean ±SD, n=3)
Fermentation C12:0, Lauric acid 13.264 22.3 1.93 ±0.04
C14:0, Myristic acid 19.597 34.6
C16:0, Palmitic acid 25.780 22.7
C18:0, Stearic acid 31.422 4.8
C18:1, Octadecanoic acid 32.003 12.8
C18:2, Linoleic acid 33.005 2.9
Centrifugation C12:0, Lauric acid 13.201 30.3 1.62 ±0.04
C14:0, Myristic acid 19.574 37.8
C16:0, Palmitic acid 25.777 23.9
C18:0, Stearic acid N/A N/A
C18:1, Octadecanoic acid 31.999 8.0
C18:2, Linoleic acid N/A N/A
nnumber of sample (water content determination)
J Am Oil Chem Soc
123
As shown in Table 3, the water content of VCO pre-
pared by the centrifugation method was significantly lower
than that found in the VCO produced by the fermentation
method (Student’s ttest, p\0.05). However, the water
content of the VCO from these two methods was higher
than the water content limit of 0.2% w/v set by the Thai
Industrial Standards Institute, TIS 203-2520 (1977). Thus,
the reduction of water content in the VCO was required in
the pilot scale production.
Owing to its being the highest amount of VCO pro-
duced, the VCO obtained from the centrifugation method
was further characterized for some of its quality indicators,
namely acid value, saponification value, ester value, iodine
value and peroxide value.
It was found that the VCO had a low acid value of about
0.13, suggesting its low susceptibility to hydrolytic ran-
cidity. The VCO had a saponification value of about 254.8,
which was in close agreement with the value reported by
Thieme [17]. Both acid and saponification values were
within the specified limit of the Thai Industrial Standards
Institute for VCO: acid value, 4; saponification value, 248–
264. The ester value of the VCO was about 254.6. The
VCO had a low iodine value of about 3.19, indicating the
presence of few unsaturated bonds and hence low suscep-
tibility to oxidative rancidity. Notably, the iodine value was
lower than that reported by other publications (7–12) [17,
18,23]. The peroxide value of 0.28 appeared to meet the
published specification [24] and the requirement of the
Thai Industrial Standards Institute.
It must be pointed out that in the current investigation,
the methods used (USP methods) to determine these
aforementioned indicators were quite different from those
recommended by the Thai Industrial Standards Institute.
The limits specified by this institute, therefore, are only a
rough guideline for the VCO quality. Nevertheless, it could
be concluded that the VCO prepared from fresh coconut by
the centrifugation method was of superior quality. It was
slow to oxidize and thus highly resistant to the develop-
ment of rancidity, as indicated by the low value of the
important quality parameters (acid, iodine and peroxide
values). However, the water (moisture) content of the oil
([0.2%) did not meet the requirement of the Thai Indus-
trial Standards Institute and this could shorten the shelf life
of the coconut oil, or make the oil more susceptible to
microbial degradation. In addition, moisture would lead to
hydrolysis, resulting in increased free fatty acid content
[17]. For this reason, reducing the amount of water in the
VCO was necessary for larger scale preparation.
Pilot Scale Production
The information above provided us with the optimal way to
extract VCO for massage application. The centrifugation
method was selected to carry out pilot scale production
because the highest amount of VCO was produced. In the
current study, three batches of VCO were prepared.
Refractive index, viscosity and % yield of each batch were
measured. The results showed that an increase in the cen-
trifugation time resulted in a much lower water content of
the VCO (\0.25%). The VCO obtained was clear, colorless
with natural coconut scent, and free from rancid odors. A
similar yield (30%) was obtained even though the scale of
production was increased from 1.5 to 3.5 L and to 6.5 L of
coconut milk. The refractive index of each batch was about
the same (1.4524) whereas the viscosity value ranged from
30.0 to 35.0 cps. The VCO from all three batches were
blended together in order to prepare the aromatherapy
massage oils.
Aromatherapy Massage Oils Prepared
from Pilot Scale VCO
As previously mentioned the major ingredients of aroma-
therapy massage oils are carrier oils and essential oils [12].
Coconut oil, as a carrier oil, is generally recognized as safe
(GRAS) by the U.S. Food and Drug Administration [3]. In
addition to its non-irritancy, coconut oil has been reported
to penetrate the skin very well, making the skin smoother
and helps to reduce fine lines and wrinkles [3]. Further-
more, Masterjohn [25] demonstrated that coconut oil had
anti-inflammatory properties, which could help to reduce
the inflammation occurring in muscles. Also, the selected
three essential oils, lemon, eucalyptus and lavender oils,
have GRAS status granted by the Flavor and Extract
Manufacturers Association (FEMA) [12]. Both lemon and
eucalyptus oils are colorless, while lavender oil is pale
yellow. Dermal LD
50
of these three essential oils is more
than 5 g/kg (rabbit) [12]. For aromatherapy use, lemon oil
has been shown to possess several useful properties, such
as treatment for poor circulation as well as stimulation of
the brain, sense organs and parasympathetic nervous sys-
tem [12]. Eucalyptus oil has also been used to treat several
illnesses, including poor circulation, rheumatic pain and
muscular problems [12]. Lavender oil, the most used
essential oil of all in aromatherapy, has been used for
treatment of headaches, exhaustion, muscular spasm,
strains, cramps and rheumatic pain [12]. Furthermore, it
has been found to absorb through the stratum corneum into
the deeper layers of the skin (epidermis/dermis) and sub-
sequently into the blood supply [26,27]. Generally, these
essential oils can relax the mind and reduce anxiety [12].
Apart from their benefits, skin irritation potential and/or
possible damage caused by these three essential oils should
be taken into account. Lavender at 10% has caused skin
sensitization in humans and animals. However, little or no
skin irritation has been observed. Lemon oil at 10% and
J Am Oil Chem Soc
123
100% has caused skin allergy in dermatitis patients (0.5%).
Eucalyptus oil at 10% has caused no skin irritation in
human but an incidence of skin sensitization has been
reported [12].
Since no chemical agents or high heat were involved in
VCO extraction in the current investigation, it was assumed
that all the nutrients and vitamins providing numerous
benefits to the skin were preserved [8]. This makes VCO
one of the most suitable carrier oils for essential oils in
aromatherapy [13]. It has been demonstrated that VCO has
positive benefits in aromatherapy massage oils, particularly
in skin care. A perfect skin coverage of VCO results in
slowing down transepidermal water loss and thus increas-
ing hydration within the skin. Accordingly, skin dryness
and roughness can subside [28].
The physical characteristics of the massages oils
including appearance, viscosity and refractive index were
investigated. The results showed that all prepared massage
oils were clear and colorless. It was observed that the
massage oil containing lemon oil had a pleasant coconut
scent and a fresh odor reminiscent of lemon peel. In the
case of eucalyptus oil, the massage oil had a pleasant
coconut scent and a fresh rosy-citronella-like, citrusy odor
of the essential oil. The VCO blended with lavender oil had
a pleasant coconut scent and a sweet, floral, refreshing odor
of the lavender oil. The increase in concentrations of
essential oils from 1 to 5% w/w resulted in increasing the
scent of massage oils. Furthermore, all the massage oils
were found to be clear and colorless after they were stored
at room temperature for 6 months.
Refractive Index and Viscosity of Massage Oils
The apparent viscosities and refractive indices of the
massage oils are summarized in Table 4. Both measure-
ments were performed when the massage oils were freshly
prepared and repeated when they had been kept at room
temperature for 6 months. The viscosities of VCO and its
Table 4 Apparent viscosity and refractive index of virgin coconut oil and blended massage oils after storage at room temperature (32 ±1°C)
for 6 months (mean ±SD, n=3)
Formulations Apparent viscosity (cps) Refractive index
0 month 6 months 0 month 6 months
VCO
a
33.5 ±2.4 35.5 ±2.1 1.4528 ±0.0001 1.4526 ±0.0004
1% w/w lemon oil in VCO 34.0 ±0.0 34.7 ±0.6 1.4535 ±0.0003 1.4529 ±0.0001
1% w/w lemon oil in VCO-E
b
33.3 ±1.2 34.3 ±0.6 1.4537 ±0.0001 1.4529 ±0.0000
d
3% w/w lemon oil in VCO 25.3 ±0.6 31.0 ±1.7
c
1.4530 ±0.0000 1.4529 ±0.0000
d
3% w/w lemon oil in VCO-E 26.3 ±0.6 30.3 ±0.6
c
1.4537 ±0.0000 1.4531 ±0.0001
d
5% w/w lemon oil in VCO 23.3 ±0.6 26.3 ±0.6
c
1.4537 ±0.0001 1.4531 ±0.0001
d
5% w/w lemon oil in VCO-E 23.7 ±0.6 26.7 ±1.2
c
1.4539 ±0.0002 1.4538 ±0.0000
1% w/w eucalyptus oil in VCO 30.0 ±0.0 36.3 ±0.6
c
1.4531 ±0.0001 1.4525 ±0.0000
d
1% w/w eucalyptus oil in VCO-E 30.3 ±0.6 37.0 ±0.0
c
1.4532 ±0.0004 1.4529 ±0.0001
3% w/w eucalyptus oil in VCO 32.7 ±1.2 32.0 ±1.0 1.4528 ±0.0000 1.4530 ±0.0000
d
3% w/w eucalyptus oil in VCO-E 33.0 ±1.0 32.7 ±1.5 1.4529 ±0.0001 1.4531 ±0.0000
5% w/w eucalyptus oil in VCO 30.3 ±0.6 30.3 ±1.5 1.4529 ±0.0001 1.4530 ±0.0000
5% w/w eucalyptus oil in VCO-E 31.0 ±0.0 31.3 ±1.2 1.4535 ±0.0004 1.4530 ±0.0000
1% w/w lavender oil in VCO 34.7 ±0.6 35.7 ±0.6 1.4527 ±0.0000 1.4527 ±0.0003
1% w/w lavender oil in VCO-E 34.7 ±0.6 35.0 ±0.0 1.4530 ±0.0000 1.4530 ±0.0000
3% w/w lavender oil in VCO 34.0 ±0.0 34.0 ±1.7 1.4527 ±0.0000 1.4523 ±0.0002
3% w/w lavender oil in VCO-E 34.3 ±0.6 34.3 ±0.6 1.4527 ±0.0000 1.4529 ±0.0000
d
5% w/w lavender oil in VCO 34.0 ±1.0 33.7 ±1.2 1.4529 ±0.0002 1.4523 ±0.0002
5% w/w lavender oil in VCO-E 34.0 ±0.0 33.3 ±2.9 1.4527 ±0.0000 1.4530 ±0.0000
d
a
VCO, virgin coconut oil from pilot scale production (three batches blended together)
b
VCO-E, virgin coconut oil with the antioxidant (0.5% w/w a-tocopherol)
c
For the same formulation, the viscosity of massage oils after 6-month storage was significantly different from that at 0 month (paired ttest,
p\0.05)
d
For the same formulation, the refractive index of massage oils after 6-month storage was significantly different from that at 0 month (paired t
test, p\0.05)
nnumber of sample
J Am Oil Chem Soc
123
aromatherapy products were rather low. For the freshly
prepared formulations, the viscosities of the massage oils
were in the range of 23.3–34.7 cps. The viscosities varied
with the compositions of the formulations. It can be seen
that the viscosity of the massage oils containing lemon oil
decreased significantly when the amount of the lemon oil
was increased from 1 to 5% w/w (One-way ANOVA,
p\0.05). The viscosity of the formulation containing
5% w/w lemon oil was the lowest. The viscosity of the
massage oil containing 3% w/w eucalyptus oil was sig-
nificantly different from that of the formulations contained
1% w/w or 5% w/w of such oil (One-way ANOVA,
p\0.05). The viscosities of massage oils at three different
concentrations of lavender oil were about the same, indi-
cating that the viscosity of lavender massage oils was not
affected by the concentrations used in the current
investigation.
After 6 months of storage at room temperature
(32 ±1°C), the viscosities of massage oil formulations
containing lemon oil at 3 and 5% w/w, with or without the
antioxidant, increased significantly (paired ttest, p\0.05).
The viscosities of massage oils containing 3 and 5% w/w
eucalyptus oil did not change whereas the viscosity of the
1% w/w concentration increased significantly (paired ttest,
p\0.05). No significant changes in viscosities were
observed in the VCO and the massage oils containing
lavender oil at all concentrations (1–5% w/w) (paired ttest,
p[0.05).
Massage usually involves the use of lubricating oils to
help the aromatherapist’s hands glide more evenly over the
customer’s skin. The viscosity of the massage oil directly
relates to how easily the oil can be massaged onto the body.
The massage oils containing lavender oil appeared to be the
most suitable oil for body massage since its viscosities
were appropriate and did not alter after 6 months of storage
at room temperature. On the other hand, the viscosities of
massage oils containing lemon oil increased during the
storage. This could affect the spreadability and the flow of
the products.
The refractive indices of all prepared massage oils at
room temperature were about 1.453 (see Table 4).
Refractive index measures the light refraction of oil. When
they were freshly prepared, the refractive index of the
massage oil containing lemon oil at 1% w/w was not sig-
nificantly different from those of the massage oils con-
taining lemon oil at 3 and 5% w/w (One-way ANOVA,
p[0.05). There were no significant differences of
refractive indices in any of massage oils containing lemon
oil plus the antioxidant (One-way ANOVA, p[0.05).
In the case of eucalyptus oil, the refractive index of the
1% w/w was significantly higher than that of the 3 and
5% w/w concentrations (One-way ANOVA, p\0.05). No
significant differences were observed when the antioxidant
was added in these eucalyptus oil formulations (One-way
ANOVA, p[0.05). For lavender oil, the refractive index
of the massage oil containing 1% w/w lavender oil was
the highest when compared to that of the 3 and 5% w/w
formulations.
After 6 months of storage at room temperature
(32 ±1°C), significant changes in the refractive indices
were found mostly in the massage oil formulations con-
taining lemon oil (paired ttest, p\0.05). Similar to the
viscosity, the refractive index of the VCO did not signifi-
cantly change after a 6-month storage period at room
temperature (paired ttest, p[0.05).
Chemical Characterization of Massage Oils
Chemical characteristics associated with oxidation and
rancidity of the massage oils are shown in Table 5.
According to the Thai Industrial Standards Institute [TIS
203-2520 (1977)], the specified limit for acid, peroxide and
iodine values are 4, 3 and 7–11, respectively. It was found
that the VCO (large scale) met the requirement of the Thai
Industrial Standards Institute. Generally, blending of
essential oils with the VCO resulted in an increase in these
three indicators. Hence, the incorporation of essential oils
into the VCO could increase the susceptibility to oxidation
and rancidity. In general, the rank order of acid value,
peroxide value and iodine value of the freshly prepared
formulations appeared to be lemon oil [lavender
oil [eucalyptus oil. Apart from the types of essential oils,
amount (concentrations) of these essential oils seemed to
affect the oxidation process. For example, in the case of
acid value, it was found that the massage oil containing 1%
lemon oil gave significant higher acid value than that of the
3 and 5% concentrations (One-way ANOVA, p\0.05).
However, no significant differences could be found in the
presence of the antioxidant. In the case of eucalyptus oil,
there were significant differences in the acid value of the
eucalyptus massage oils at three different concentrations
(ANOVA, p\0.05). Overall, the highest acid value was
obtained in the massage oil containing 1% w/w lemon oil
whereas the lowest value seemed to observe in the for-
mulation containing 3% w/w eucalyptus oil with the
antioxidant.
It is known that coconut oil is very resistant to the
development of rancidity since it has a low content of
oxidizable unsaturated fatty acids. In addition, VCO itself
contains beneficial natural antioxidants, namely tocophe-
rols which can protect the oil against atmospheric oxidation
and rancidity [29]. In an attempt to increase the antioxidant
protection, extra tocopherol was also added to the formu-
lations. According to the Thai Industrial Standards Institute
[TIS 203-2520 (1977)], both natural and synthetic toco-
pherols are recommended for use as antioxidants for
J Am Oil Chem Soc
123
coconut oil. When the formulations with and without the
antioxidant were compared, it was found that the acid
values of the formulations containing the antioxidant
showed a tendency to reduce, although significant reduc-
tion was observed only in the massage oils containing
lemon oil at 3% w/w or eucalyptus oil at 5% w/w
(Table 5) (Student’s ttest, p\0.05). The peroxide values
of the preparations with the antioxidant were generally
higher than those of the formulations without the antioxi-
dant. A significant decrease in the peroxide value was
found only in the massage oil containing lavender oil at
1% w/w (Student’s ttest, p\0.05).
In the case of the iodine value, no significant differences
were found in the formulations containing lemon oil at
every concentration. For lavender oil, a significant increase
in the iodine value was observed in the formulation con-
taining the highest concentration of lavender oil (5% w/w)
(Student’s ttest, p\0.05). The significant increase in the
iodine value was found in the formulations containing
eucalyptus oil at the concentrations higher than 1% w/w
(Student’s ttest, p\0.05). The result suggests that the
iodine value of the formulations is affected by types and
concentrations of the essential oils. Generally, tocopherol
at 0.5% w/w concentration did not seem to have significant
inhibitory effects on the oxidation reaction as it was
expected. Apart from increasing the amount of the anti-
oxidant, it is likely that the addition of antioxidant-syner-
gists into the formulations may enhance the effect of
tocopherol. Further investigation using higher concentra-
tions of tocopherol or certain antioxidant-synergists is
recommended for future work.
Antimicrobial Properties of Massage Oils
As seen in Table 6, VCO and its massage oil formulations
did not exhibit antibacterial or antifungal activities on the
microorganisms tested. These findings are not in agreement
with the results reported by Ogbolu et al. [30]. Using the
agar-well diffusion technique, they found that VCO
showed antifungal properties against Candida species,
Table 5 Quality characteristics of virgin coconut oil and freshly prepared blended massage oils (mean ±SD, n=3)
Formulations Quality characteristics of blend oils
Acid value
(mg of KOH/1 g oil)
Peroxide value
(mequiv/1,000 g oil)
Iodine value
(g of iodine/100 g oil)
VCO
a
0.118 ±0.040 0.160 ±0.058 7.371 ±0.620
1% w/w lemon oil in VCO 0.351 ±0.026 0.277 ±0.108 19.746 ±0.257
1% w/w lemon oil in VCO-E
b
0.231 ±0.096 2.220 ±0.699
d
20.588 ±0.561
3% w/w lemon oil in VCO 0.246 ±0.019 1.946 ±0.954 17.524 ±0.341
3% w/w lemon oil in VCO-E 0.167 ±0.045
c
3.303 ±1.676 20.730 ±2.278
5% w/w lemon oil in VCO 0.211 ±0.031 6.990 ±3.848 23.485 ±5.622
5% w/w lemon oil in VCO-E 0.227 ±0.018 6.106 ±0.492 24.546 ±2.335
1% w/w eucalyptus oil in VCO 0.205 ±0.025 0.976 ±0.339 6.920 ±0.672
1% w/w eucalyptus oil in VCO-E 0.211 ±0.041 1.746 ±0.095
d
8.321 ±1.142
3% w/w eucalyptus oil in VCO 0.093 ±0.020 1.510 ±0.489 8.310 ±0.059
3% w/w eucalyptus oil in VCO-E 0.066 ±0.012 2.859 ±0.518
d
8.879 ±0.254
d
5% w/w eucalyptus oil in VCO 0.148 ±0.018 1.570 ±0.453 11.158 ±0.123
5% w/w eucalyptus oil in VCO-E 0.140 ±0.028 2.722 ±1.154 11.823 ±0.223
d
1% w/w lavender oil in VCO 0.123 ±0.024 3.159 ±0.240 9.079 ±0.799
1% w/w lavender oil in VCO-E 0.111 ±0.010 1.470 ±0.500
c
9.126 ±0.202
3% w/w lavender oil in VCO 0.107 ±0.021 0.812 ±0.302 10.753 ±1.031
3% w/w lavender oil in VCO-E 0.095 ±0.013 1.672 ±0.399
d
11.681 ±0.633
5% w/w lavender oil in VCO 0.254 ±0.006 0.698 ±0.539 12.481 ±0.075
5% w/w lavender oil in VCO-E 0.170 ±0.049
c
1.405 ±0.245
d
13.409 ±0.275
d
a
VCO, virgin coconut oil from pilot scale production (three batches blended together)
b
VCO-E, virgin coconut oil with the antioxidant (0.5% w/w a-tocopherol)
c
A significant reduction in the acid value or peroxide value was observed (Student’s ttest, p\0.05) when compared with the formulation
without tocopherol
d
A significant increase in the peroxide value or iodine value was observed (Student’s ttest, p\0.05) when compared with the formulation
without tocopherol
nnumber of sample
J Am Oil Chem Soc
123
particularly C. albicans. It has been reported that lauric
acid and short chain fatty acids (caprylic and capric acids)
show antimicrobial effects [22]. Although the VCO con-
tained reasonable amounts of lauric acid, the antimicrobial
effects were not detected. It might be speculated that these
microorganisms may be more susceptible to short chain
fatty acids which were not found in our VCO.
In addition to VCO, essential oils used in the current
study, especially lavender oil and eucalyptus oil, have been
reported to exhibit extensive antimicrobial activities [12],
[31,32]. In deed, it was found that pure lavender oil,
eucalyptus oil and lemon oils were effective against the test
bacteria (see Table 6). Nevertheless, the inhibitory prop-
erties of essential oils in combination with VCO were not
observed in the current investigation. This is probably due
to the fact that the amount of essential oils used may not be
sufficient to inhibit the microbial growth. Furthermore, the
antimicrobial effects of these essential oils may be diluted
by adding VCO. Similarly, Donoyama et al. [33] found that
undiluted tea tree oil exhibited antibacterial activity against
S. aureus in vitro, but it was not effective when added to a
jojoba base oil. After 6 months of storage at room tem-
perature, the VCO and its massage oils were found not to
show any antibacterial or antifungal activities on the test
microorganism.
Microbial Counts in VCO and Blended Massage Oils
To ensure the safety of the products, a microbial count was
performed. Aerobic bacteria, mold and yeast were not
detected in the VCO and massage oil formulations. In
addition, a similar result was observed after the prepara-
tions were stored at room temperature for 6 months. This
result indicates that the preparations were free from
microbial contamination and considered safe for
customers.
Accelerated Storage Stability Studies
The storage stability of the VCO and the massage oil for-
mulations was carried out at high temperature of 45 °Cin
order to accelerate oxidation development. Acid, iodine
and peroxide values of these preparations were measured to
examine possible rancidity. It was found that the devel-
opment of rancidity of VCO and its massage oil products
occurred during storage at elevated temperature as indi-
cated by the significant increase in the acid value and
peroxide value in most formulations (paired ttest,
p\0.05) (Figs. 1,2). For example, both acid and peroxide
values of the massage oils containing lavender oil
increased significantly after the formulations were stored at
45 °C for 4 months (paired ttest, p\0.05) (Figs. 1c, 2c).
Similar to lavender oil, the massage oil formulations con-
taining eucalyptus oil or lemon oil, which were stored at
accelerated condition, exhibited higher acid and peroxide
values than those of such freshly prepared formulations.
However, no significant differences of these values were
observed at some concentrations of these oils (paired ttest,
p[0.05) (see Figs. 1a, b, 2a, b). Based on the aforemen-
tioned results, it can be summarized that lavender oil was
Table 6 Antimicrobial properties of virgin coconut oil and blended massage oils compared with positive controls (mean ±SD, n=3)
Blended massage oils Inhibition zone (mm)
S. aureus
ATCC 25923
E. coli
ATCC 25922
P. aeruginosa
ATCC 27853
B. subtilis C. albicans
VCO
a
––– ––
5% w/w lemon oil in VCO – – – – –
5% w/w lemon oil in VCO-E
b
––– ––
5% w/w eucalyptus oil in VCO – – – – –
5% w/w eucalyptus oil in VCO-E – – – – –
5% w/w lavender oil in VCO – – – – –
5% w/w lavender oil in VCO-E – – – – –
Lemon oil 18.67 ±0.29 28.50 ±0.70 21.07 ±1.03 17.10 ±0.36 –
Eucalyptus oil – 27.37 ±2.51 16.77 ±1.46 – –
Lavender oil – – 17.07 ±1.60 14.12 ±0.35 –
Gentamicin HCl (16 lg/mL) 25.6 ±4.32 22.0 ±3.0 16.5 ±1.2 30.0 ±2.25 n.d.
Ketoconazole (5 lg/mL) n.d. n.d. n.d. n.d. 35.0 ±4.75
a
VCO, virgin coconut oil from pilot scale production (three batches blended together)
b
VCO-E, virgin coconut oil with the antioxidant (0.5% w/w a-tocopherol)
–, no inhibition zone was observed; n.d. not determined; nnumber of sample
J Am Oil Chem Soc
123
highly susceptible to oxidation processes followed by
lemon oil and eucalyptus oil. In contrast to the acid and the
peroxide values, the iodine value of the VCO after
4 months of storage at accelerated temperature was sig-
nificantly lower than the initial iodine value (paired ttest
p\0.05) (Fig. 3). It is generally recognized that a
decrease in the iodine value indicates a decrease in
unsaturated fatty acids. Hence, it was likely that the
reduction of these unsaturated acids occurred during the
storage.
*
*
*
*
**
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
VCO 1% 1% +
tocopherol 3% 3% +
tocopherol 5% 5% +
tocopherol
VCO 1% 1% +
tocopherol 3% 3% +
tocopherol 5% 5% +
tocopherol
VCO 1% 1% +
tocopherol 3% 3% +
tocopherol 5% 5% +
tocopherol
Lemon oil (%w/w)
Acid value
0 month
4 months
*
*
*
**
*
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Eucalytus oil (%w/w)
Acid value
0 month
4 months
B
A
*
***
**
*
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
Lavender oil (%w/w)
Acid value
0 month
4 months
C
Fig. 1 Acid values of virgin coconut oil (VCO) and blended massage
oils after 4 months at 45 °C; lemon oil (a), eucalyptus oil (b) and
lavender oil (c). Each value represents mean ±S.D. (n=3, nnumber
of sample). *Acid value of the sample at 0 month is significantly
different from that at 4-month storage at 45 °C (paired ttest,
p\0.05)
*
*
*
*
*
*
0
5
10
15
20
25
VCO 1% 1% +
tocopherol
3% 3% +
tocopherol
5% 5% +
tocopherol
VCO 1% 1% +
tocopherol 3% 3% +
tocopherol 5% 5% +
tocopherol
VCO 1% 1% +
tocopherol
3% 3% +
tocopherol
5% 5% +
tocopherol
Lemon oil (%w/w)
Peroxide value
0 month
4 months
*
*
*
*
0
5
10
15
20
25
30
35
Eucalyptus oil (%w/w)
Peroxide value
0 month
4 months
A
B
*
*
*
*
*
*
*
0
5
10
15
20
25
30
35
Lavender oil (%w/w)
Peroxide value
0 month
4 months
C
Fig. 2 Peroxide values of virgin coconut oil (VCO) and blended
massage oils after 4 months at 45 °C; lemon oil (a), eucalyptus oil (b)
and lavender oil (c). Each value represents mean ±S.D. (n=3,
nnumber of sample). *Peroxide value of the sample at 0 month is
significantly different from that at 4-month storage at 45 °C (paired
ttest, p\0.05)
J Am Oil Chem Soc
123
Generally, the iodine value of the massage oils at the
accelerated temperature was not significantly different
from the initial value (paired ttest, p[0.05) (Fig. 3).
Besides, the reduction of the iodine value was observed in
some formulations. In the case of lemon oil, the formula-
tions containing 1% w/w lemon oil with and without
tocopherol showed a significant decrease in the iodine
value (paired ttest, p\0.05) (Fig. 3a). However, there
was no significant difference in the iodine value at higher
concentrations of the oil (paired ttest, p[0.05). For
eucalyptus oil, the iodine value showed significant reduc-
tion in the formulations containing 1% w/w concentration
with tocopherol whereas no significant differences were
found in the other formulations (Fig. 3b). In the case of
lavender oil, the iodine value did not significantly change
after the storage at accelerated temperature (paired ttest,
p[0.05) (Fig. 3c). A significantly lower iodine value was
found only in the formulation containing 1% w/w lavender
oil with the antioxidant (paired ttest, p\0.05). It is
interesting to note that at the end of storage period, the acid
and peroxide values of the VCO and massage oils
increased, whereas the iodine value showed a tendency to
decrease. Similarly, Anwar et al. [34], who studied the
effect of Moringa oleifera oil on the oxidative stability of
some vegetable oils, reported that with the advance of the
storage period (ambient temperature), the peroxide values
of the investigated oils increased from the initial values,
whereas the iodine values of the oils decreased. After
4 months of storage at 45 °C, the VCO and the massage oil
formulations were still clear and colorless with aromatic
scents of coconut oil and essential oils.
At accelerated condition of 45 °C, the positive effect of
tocopherol was demonstrated to some extent by the acid
value. Generally, the acid values of stored formulations
containing tocopherol (0.5% w/w) tended to be lower than
those of such formulations without antioxidant (Fig. 1).
The significant reduction in the acid value was observed in
the stored formulations containing 3% lemon oil or 3%
eucalyptus oil in the presence of the antioxidant (Student’s
ttest, p\0.05). Contrary to the acid value, the peroxide
values of the stored formulations containing tocopherol
were significantly higher than those of such formulations
without the antioxidant (Student’s ttest, p\0.05) (Fig. 2).
In generally, the iodine values of the stored formulations
with tocopherol did not significantly differ from those of
such formulations without tocopherol (Fig. 3).
The present oxidative stability data suggest that VCO
and the aromatherapy massage oils should not be stored at
high temperature. In order to gain more storage stability
details, a further stability study using lowered storage
temperatures (i.e. 4 °C, room temperature) and different
storage periods needs to be performed to determine the
effects of these parameters on the storage stability of the
massage oil products.
Positive Remarks of VCO and Massage Oil
Formulations
For tropical countries, especially Thailand, VCO can be
used as an easily accessible source of vegetable base oil
for aromatherapy. In the current study, VCO, which was
*
*
*
0
5
10
15
20
25
30
35
VCO 1% 1% +
tocopherol
3% 3% +
tocopherol
5% 5% +
tocopherol
VCO 1% 1% +
tocopherol
3% 3% +
tocopherol
5% 5% +
tocopherol
VCO 1% 1% +
tocopherol
3% 3% +
tocopherol
5% 5% +
tocopherol
Lemon oil (%w/w)
Iodine value
0 month
4 months
*
*
*
0
2
4
6
8
10
12
14
Eucalyptus oil (%w/w)
Iodine value
B
A
*
*
0
2
4
6
8
10
12
14
16
Lavender oil (%w/w)
Iodine value
0 month
4 months
C
0 month
4 months
Fig. 3 Iodine values of virgin coconut oil (VCO) and blended
massage oils after 4 months at 45 °C; lemon oil (a), eucalyptus oil (b)
and lavender oil (c). Each value represents mean ±S.D. (n=3,
nnumber of sample). *Iodine value of the sample at 0 month is
significantly different from that at 4-month storage at 45 °C (paired
ttest, p\0.05)
J Am Oil Chem Soc
123
produced by the centrifugation process, seemed to meet the
specifications of the Thai Industrial Standards Institute.
VCO was a good source of saturated fatty acids such as
myristic acid and lauric acid. The saturation of VCO and
the low values of the important quality parameters obtained
suggest its high stability and low susceptibility to becom-
ing rancid. Using visual inspection, all the prepared mas-
sage oils exhibited good physical stability as shown by no
color change and no precipitation during the study periods
of 4 months or 6 months at 45 °C and at room temperature,
respectively. In addition, there was no alteration in the
aromatic scents of the massage oils during the storage
periods. The apparent viscosities of freshly prepared aro-
matherapy products were rather low and thus only small
pressure was required to rub the massage oils onto the skin.
Due to their low viscosities, the massage oil preparations
could be easily spread over the skin surface. It was
revealed that the viscosities of some formulations, partic-
ularly the formulations containing lavender oil, did not
alter after a 6-month storage period at room temperature.
Importantly, both fresh and stored massage oil preparations
were free from microbial contamination.
Conclusions
This study has revealed that the most appropriate method for
VCO extraction was centrifugation as it gave the highest
yield of VCO. The VCO obtained was clear, colorless with a
pleasant coconut scent. Most of the fatty acids found in the
VCO prepared by the centrifugation method were saturated
and the predominant saturated fatty acid was myristic acid.
All the prepared massage oils were clear and colorless with
the characteristic odor of each essential oil (lemon oil,
eucalyptus oil and lavender oil). The viscosity and refractive
index of the massage oils was somewhat affected by the
formulation composition. In an attempt to increase the oxi-
dative stability of the formulations, additional antioxidant,
5% w/w tocopherol, was added into the massage oils. The
results showed that the tocopherol did not seem to have any
significant inhibitory effects on the oxidation reaction as it
had been expected. Both types and concentrations of the
essential oils influenced the oxidation and rancidity of the
aromatherapy massage oils as indicated by the alteration of
the three indicators; acid, peroxide and iodine values. Gen-
erally the rank order of acid value, peroxide value and iodine
value of freshly prepared massage oils appeared to be lemon
oil [lavender oil [eucalyptus oil. During storage at high
temperature (45 °C) for a period of 4 months, both acid
value and peroxide value of VCO and the massage oils were
found to increase from the initial values whereas the iodine
value of the preparations tended to decline. The massage oils
containing lavender oil were found to be highly susceptible
to the oxidation process followed by lemon oil and euca-
lyptus oil. Antimicrobial activity was not observed in the
VCO and the massage oils. In addition, VCO and its massage
oil products were considered safe for customers since they
were free from microbial contamination.
Acknowledgments The authors would like to acknowledge
National Research Council of Thailand for financial support. The
authors wish to thank Faculty of Pharmaceutical Sciences, Prince of
Songkla University, Thailand, for their facilities and contributions.
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