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Review Article
Thien Hien Tran*, Thi Kim Ngan Tran, Thi Cam Quyen Ngo, Tri Nhut Pham, Long Giang Bach,
Nguyen Quynh Anh Phan, Thi Hong Nhan Le*
Color and composition of beauty products
formulated with lemongrass essential oil:
Cosmetics formulation with lemongrass
essential oil
https://doi.org/10.1515/chem-2021-0066
received March 22, 2021; accepted June 5, 2021
Abstract: Diversification of products that are derived from
essential oils carries important implications in reducing
agricultural waste and promoting the medicinal materials
industry. In this study, we formulated a shampoo and
a body wash product incorporated with lemongrass
(Cymbopogon citratus)essential oils (LEOs)and evaluated
their color stability and the LEO compositional change. We
first determined the color change and chemical composition
of bare LEO under different storage conditions. Afterward,
the washing product base was formulated, and its formula-
tion process was optimized to minimize the color change by
varying a wide range of parameters including pH, the inclu-
sion of preservatives and antioxidants, LEO/antioxidant
ratio, and emulsification temperature. The base product was
then used in body wash and shampoo formulation following
our previously reported procedure. The results indicated that
direct incorporation of the LEO into the cosmetic products
resulted in better color stability and citral retention in com-
parison with emulsion formation. In addition, shampoo and
body wash products showed no detectible presence of
compounds resulting from citral decomposition such as
3,7-dimethyl-1,3,6-octatriene, p-mentha-1,5-dien-8-ol, and
p-cymene-8-ol. The current findings are expected to aid in
diversifying LEO-derived commodities and justifying scal-
ability of the cosmetics production process with a focus on
the incorporation of naturally derived ingredients.
Keywords: Cymbopogon citratus, essential oils, shampoo,
body wash, color stability, cosmetic formulation
1 Introduction
Lemongrass (Cymbopogon citratus)is a common plant
ingredient that is used widely in daily applications and
in folk medicine [1–4]. The main product derived from the
lemongrass plant, lemongrass essential oil (LEO), is also
a commodity that is widely used in the food industry due
to its predominant content of citral in its composition,
which confers the LEO with potent antibacterial activity
and pleasant, favorable aroma [5–8]. Additionally, the
LEO is also a common material in the manufacture of
medicinal products such as antifungal agents, antide-
pressants, and indigestion remedies.
Despite that, the increasingly rapidly growing area of
lemongrass has brought about excess output on both the
raw material and LEO, causing difficulty in solving the
surplus LEO and calling for diversification of products
that are mainly or partially derived from LEO. Apart
from medicinal products, products that are manufactured
* Corresponding author: Thien Hien Tran, Department of Chemical
Engineering, Ho Chi Minh City University of Technology, 268 Ly
Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam; Vietnam
National University Ho Chi Minh City, Linh Trung Ward, Thu Duc
District, Ho Chi Minh City 700000, Vietnam; Institute of
Environmental Sciences, Nguyen Tat Thanh University, Ho Chi Minh
City, Vietnam, e-mail: 1870148@hcmut.edu.vn
Thi Kim Ngan Tran, Thi Cam Quyen Ngo, Tri Nhut Pham, Long Giang
Bach: Institute of Environmental Sciences, Nguyen Tat Thanh
University, Ho Chi Minh City, Vietnam; Center of Excellence for
Biochemistry and Natural Products, Nguyen Tat Thanh University,
Ho Chi Minh City, Vietnam
Nguyen Quynh Anh Phan: Department of Chemical Engineering, Ho
Chi Minh City University of Technology, 268 Ly Thuong Kiet Street,
District 10, Ho Chi Minh City, Vietnam; Vietnam National University
Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh
City 700000, Vietnam
* Corresponding author: Thi Hong Nhan Le, Department of Chemical
Engineering, Ho Chi Minh City University of Technology, 268 Ly
Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam; Vietnam
National University Ho Chi Minh City, Linh Trung Ward, Thu Duc
District, Ho Chi Minh City 700000, Vietnam,
e-mail: lthnhan@hcmut.edu.vn
Open Chemistry 2021; 19: 820–829
Open Access. © 2021 Thien Hien Tran et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0
International License.
with LEO as a major component are quite limited in
Vietnam, mostly comprising insect repellent products
and a relaxation agent. As a result, new and novel attempts
to incorporate LEO into consumers’products such as per-
sonal care and home products are essential to the valoriza-
tion of lemongrass and contribute to ease the burden of
lemongrass output in the upcoming years [9,10].
The main challenge in introducing LEO into con-
sumer products is that the citral component in LEO is
highly susceptible to conversion by acid catalysts and
oxidative degradation, especially in the presence of light
and heat, leading to the formation of the intensity change
of flavor [11,12]. The decomposition of citral is more expe-
dited at a higher temperature, light, and available oxygen
in this compound and may produce other compounds
such as p-cymene, p-cymene-8-ols, p-mentha-1,5-dien-8-ol,
p-menthadien-8-ol, α,p-dimethylstyrene, p-methylaceto-
phenone, and p-cresol, which may further alter the
aroma intensity of LEO [12–18]. To address this issue,
various measures have been devised to prevent or mitigate
the decomposition of citral, including the use of spray-
drying technique, the formation of oil-in-water emulsions,
and the manufacture of micelles and reverse micelles to
stabilize citral in the oil phase [19–21].However,suchtech-
niques are more labor-intensive and require modern instru-
ments, thus considerably escalating manufacturing costs
and in turn affecting consumers’acceptance due to the
high price sensitivity of demands for home products.
Driven by the aforementioned trusts, this study aims
to evaluate the stability of LEO in the formulation of various
cosmetic products. We first evaluated the color change and
chemical composition of LEO under different storage condi-
tions. Then, the formulating process of a washing product
base was optimized to minimize the color change in the base.
The best product base was then used in the formulation of
two cosmetic products, including body wash and shampoo,
following our previously reported procedure. Finally, the two
products were then evaluated for the LEO volatile composi-
tion and color change. The findings are expected to aid in
diversifying LEO-derived commodities and justifying the
scalability of the cosmetics production process with a focus
on the incorporation of naturally derived ingredients.
2 Materials and methods
2.1 Materials
LEO was obtained by steam distillation of the leaves of
emongrass (Cymbopogon citratus)harvested from Tan Phu
Dong district, Tien Giang province, Vietnam (Coordinates
10°15′N106°39′E). The extraction apparatus was of industrial
scale and operated under the following conditions: extrac-
tion time, 3 h; material quantity, 639–710 kg per batch. The
highest LEO yield was 0.273% (v/w).
2.2 Formulation of simulated product base
incorporated with LEO
Formulation of the product base was realized by using
base oil, emulsifier, or the lack thereof. The simulated
product base was formulated by using four ingredients
including LEO, preservatives, additives (base oil, emul-
sifier, or none), antioxidants, and water. The LEO (and
additive)mixture was first mixed with preservatives and
antioxidants. The afforded mixture was introduced into
heated water (70–80°C)under stirring. The result-
ing mixture was then allowed to naturally cool and
homogenized.
The formulation process was first investigated with
respect to different base oils (PEG-40 hydrogenated castor
oil (PEG-400),paraffin oil, and none), varying emulsifica-
tion temperature (room temperature to 90°C),anddif-
ferent emulsifiers (Tween 80, Tween 20, PEG 40, and
none). After determining the appropriate formulation
technique, the process was then further optimized by
experimenting at different pH values (4–7),different preser-
vatives (sodium benzoate, sodium lactate, DMDM hydantoin
(DMDM-H)), antioxidants (butylated hydroxyanisole (BHA),
and butylated hydroxy toluene (BHT)), and antioxidant/LEO
ratio (0.5:1–2.5:1).
2.3 Formulation of body wash and shampoo
products incorporated with LEO
The body wash formulation process was carried out by using
the product base following a previous report [20].Briefly, the
product base was separately formulated with the composi-
tion and conditions that were determined in previous inves-
tigations. Then, another mixture consisting of the main
detergent, detergent adjuvant, thickener, foaming agent,
humectant, preservative, and skin emollient was prepared
separately before being introduced into the mixture. After-
ward, NaCl 25% and citric acid 30% were added to the mix-
ture. Finally, the body wash was cooled and poured into a
bottle for further evaluation.
Cosmetics formulation with lemongrass essential oil 821
The shampoo product was formulated similarly to the
body wash formulation, except that the BHT/LEO ratio in
the washing base was fixed at 0.5:1 (w/w)[19].
2.4 Determination of pH and the color
change
The MP220 pH meter (Mettler Toledo)was used to deter-
mine the pH of the sample. The product samples were
diluted 100 times before the pH measurement for accu-
rate determination.
The color of the samples was measured by using a CR-
400 colorimeter (Konica Minolta, Japan).Theliquidproduct
was stored in a glass cuvette placed in a dark chamber for
the measurement. The color oftheproductwasdetermined
by the color space L*a*b*. The L*a*b*colorspaceissphe-
rical with three axes: L,a,b.Thea-axis runs from −a*
(green)to +a*(red)and the b-axis runs from −b*(light
green)to +b*(yellow). The brightness axis L*isvalid
from 0 (black at the bottom)to 100 (white at the top).
The color differences between samples or time points
are determined as follows:
=−LL LΔ
2
1
=−aa aΔ
2
1
=−bb bΔ
2
1
=++ELabΔΔΔΔ
222
where L,a, and brepresent lightness, a-axis, and b-axis,
respectively, Subscripts 2 and 1 represent after and before
color change, respectively, and
E
∆
is the color change
indicator.
2.5 Determination of chemical composition
LEOs present in the product samples were first recovered
by using hydrodistillation before the samples were used
to determine the chemical composition. Briefly, 100 g of
the sample was first introduced in water in the ratio of 1:4
(w/w). Hydrodistillation was carried out at a temperature
of 120°C until no essential oil could be recovered from the
apparatus.
Gas chromatography-mass spectrometry (GC-MS)was
adopted to determine the composition of LEO. About 25 μL
of the essential oil was diluted in 1.0 mL of n-hexane and
dehydrated with Na
2
SO
4
salt. The equipment used was GC
Agilent 6890 N (Agilent Technologies, Santa Clara, CA,
USA), with MS 5973, HP5-MS column, and column head
pressure of 9.3 psi. GC-MS was installed under the fol-
lowing conditions: He carrier gas; flow rate, 1.0 mL/min;
split line, 1:100; injection volume, 1.0 μL; and injection
temperature, 250°C. The initial temperature was kept at
50°C for 2 min; the oven temperature increased to 80°C
at a speed of 2°C/min, from 80 to 150°C at a speed of
5°C/min, from 150 to 200°C at a speed of 10°C/min, from
200 to 300°C at a speed of 20°C/min, and maintained at
300°C for 5 min.
Ethical approval: The conducted research is not related to
either human or animal use.
3 Results and discussion
3.1 Color and compositional changes of LEO
during storage
The obtained LEO via hydrodistillation was light yellow
in color with a characteristically strong citrusy and lemony
aroma. The color changes of different LEO samples are
detailed in Table 1. At ambient temperature, the color of
LEO tended to become darker as the storage time pro-
longed, yielding the ΔEvalues of 0.82 and 3.63 for LEO
stored after 1 week and 1 month, respectively. However,
visual examination of LEO samples revealed that these
color changes are indiscernible due to the insignificant
Table 1: Color changes of LEO under different storage and extraction conditions
Index Initial LEO LEO after 1 week at
ambient temperature
LEO after 1 month at
ambient temperature
LEO after
1 week at 45°C
LEO after
1 month at 45°C
Redistilled LEO after
1 month at 45°C
L61.98 62 61.99 61.79 60.09 62.48
a−7.82 −7.89 −8.4 −8.9 −8.21 −3.87
b22.57 23.39 26.15 30.47 42.13 10.54
ΔE—0.82 3.63 7.15 16.09 20.57
822 Thien Hien Tran et al.
change in the intensity of the Lindex. By contrast, storage
at elevated temperature seemed to cause more pronounced
darkening in samples, reflected by significantly higher
ΔEvalues compared to their respective values of LEO
measured at ambient temperature. The role of heat in accel-
erating citral transformation has been documented by Pea-
cock and Kuneman [22]. On the other hand, the redistilled
LEO displayed a much lighter yellow in color, less pungent
aroma than other samples, and was obtained in a lower
yield due to the mass loss of around 35.91% of the total
essential oil. According to Weerawatanakorn et al. [23],aro-
matherapy compounds are susceptible to chemical changes
that occur in different types of interactions, including oxi-
dation, hydrolysis, thermal destruction, photochemical,
and polymerization of unsaturated compounds, adversely
affecting the overall fragrance quality of the product. There-
fore, the storage temperature of 45°C was selected as the
baseconditioninthesubsequent experiment measuring
compositional changes in product formulations (Figure 1).
The major compounds that were present in the initial
LEO sample are summarized in Table 2. In total, 11 vola-
tile compounds were identified, accounting for 99.79% of
the total LEO content, of which the percentage of citral
amounted to 86.90%, followed by β-myrcene (5.656%),
and nerol (3.887%). Other components lower than 1%
included 6-methyl-5-hepten-2-one, β-linalool, β-citronellol,
geraniol acetate, β-caryophyllen, α-bergamotene, and
selina-6-en-4-ol. The composition of LEO in the present
sample is similar to that of a previous study where LEO
extracted from the lemongrass materials of the same
origin showed citral and β-myrcene contents of 79.33
and 16.65%, respectively [21]. The abundance of citral is
in line with the result of another review that indicated
that LEO contained at least 75% citral and other minor
ingredients such as nerol, geraniol, citronellal, terpino-
lene, geranyl acetate, myrecene, and terpinol methylhep-
tenone [24]. The beneficial effect of citral on the skin
membrane was elaborated by a previous study where
citral-rich LEO was found to exhibit potent antifungal
activities against several yeasts of Candida species and
did not cause skin irritation [25]. Furthermore, Modak
and Mukhopadhaya [26]also demonstrated the antiobe-
sity effects of citral in a rat model and suggested that
the effect could be attributable to the influence of citral
on energy production, thus reducing fat accumulation.
The role of citral in the food industry was also highlighted
by a previous finding suggesting that citral-containing
nanoemulsion exhibited potent antibacterial and antibio-
film activity against Listeria monocytogenes, a common
foodborne pathogen [27](Figure 2).
The compositional stability of LEO was further eval-
uated by performing GC-MS analysis of LEO samples
stored for a week, for a month at 45°C, and the redistilled
LEO sample. In comparison with citral contents of the
initial LEO, the 1-month LEO sample stored at 45°C showed
a moderately reduced percentage in α-and β-citral con-
tents, reaching 44.214 and 35.026% respectively. This LEO
sample also indicated the presence of three new com-
pounds that had not been previously detected in the initial
LEO, including 3,7-dimethyl-1,3,6-octatriene (0.395%),
p-1,5-menthadien-8-ol (0.768%),andp-cymen-8-ol (1,154%).
However, after being redistilled, the three compounds
were no longer detected in the LEO. These results imply
that the oxidation of citral occurred during storage due to
exposure to heat and light and are consistent with the
results of Weerawatanakorn et al. [23]and Ueno et al.
[28], which found that the oxidation products of citral,
including p-menthadien-8-ol, α,p-dimethylstyrene, p-cymene,
p-methylacetophenone, and p-cresol, resulted in a loss of
flavor in the LEO.
In general, exposure to both heat and light and
extended preservation have led to the degradation of
citral content and color quality. Some compounds such
as p-menthadien-8-ol and p-cymene were generated in
Figure 1: Color change of LEO at different time points: (a)initial LEO; (b)after 1 week at room temperature; (c)after 1 month at room
temperature; (d)after 1 week at 45°C; (e)after 1 month at 45°C; and (f)redistilled LEO.
Cosmetics formulation with lemongrass essential oil 823
Table 2: Chemical compositions of LEO under different storage and extraction conditions
No. RT (min)Compounds Content (%)
Initial LEO LEO after
1 week at 45°C
LEO after
1 month at 45°C
Redistilled LEO after
1 month at 45°C
1 9.771 6-Methyl-5-hepten-2-one 0.805 1.149 1.314 1.529
2 9.907 β-Myrcene 5.656 6.025 10.867 3.887
3 12.427 3,7-Dimethyl-1,3,6-
octatriene
—— 0.395 —
4 16.097 β-Linalool 0.754 0.664 0.805 1.024
5 19.799 p-Mentha-1,5-dien-8-ol —— 0.768 —
6 20.667 p-Cymene-8-ol —0.288 1.154 —
7 22.727 β-Citronellol 0.499 0.547 0.572 0.681
8 23.166 β-Citral 39.031 38.699 35.026 38.697
9 23.710 Nerol 3.887 3.583 3.612 4.402
10 24.337 α-Citral 47.868 47.588 44.214 46.802
11 28.050 Geraniol acetate 0.602 0.361 0.525 1.610
12 28.980 β-Caryophyllen 0.296 0.339 0.324 0.357
13 29.482 α-Bergamotene 0.267 0.309 0.234 0.449
14 33.884 Selina-6-en-4-ol 0.115 0.200 0.189 0.313
Citral content 86.899 86.287 79.240 85.499
Figure 2: Chromatography of essential oil samples at different storage conditions: (a)initial; (b)after 1 week at 45; (c)after 1 month at 45;
and (d)redistilled LEO.
824 Thien Hien Tran et al.
the process, necessitating further investigation in preser-
ving valuable compounds in LEOs when it is being for-
mulated in cosmetic products.
3.2 Color of the product base during
formulation
3.2.1 Effects of base oil, emulsifier, and emulsification
temperature
Incorporation of LEO into cosmetic products is usually
realized through two main approaches: direct mixing
and via the formation of emulsions. In the first investiga-
tion (effect of base oil on the product color), formulation
conditions consisted of the following: LEO content, 3%;
BHT, 1.5%; PEG-40, 15%; sodium benzoate, 0.6%; sodium
lactate, 2%; DMDM-H, 0.6%; and emulsification tempera-
ture, 70°C. All formulated product bases showed an aroma
almost identical with that of the LEOs after short and con-
stant storage conditions (7 days at 45°C).
Table 3 shows the color changes of simulated product
base formulated at different temperatures, base oils (PEG-
400, paraffin oil, and none), and emulsifiers (Tween 80,
Tween 20, PEG-40, and none). Generally, two samples
that were devoid of base oils or emulsifiers showed the
lowest ΔEvalues, of 0.96 and 0.87, respectively, indi-
cating that base oils and emulsifiers play a key role in
inducing color changes in the product base formulations
with LEO [29–31]. Further examination of the formulated
bases showed that the LEO layering phenomenon emerged
in the sample incorporated with paraffin. After 7 days of
preservation at 45°C, bases formulated with PEG-400
and paraffin exhibited moderate discoloration toward
yellow and revealed instability. Overall, the direct mixing
of LEO into product bases seemed to result in little
change in color in comparison with the emulsion route.
Therefore, direct mixing of LEO would be done in subse-
quent experiments.
3.2.2 Effects of formulation conditions on the product
base color
Influence of other mixing conditions including pH (4–7),
preservative (sodium lactate, sodium benzoate, and DMDM-
H), antioxidant (BHT and BHA), and antioxidant/LEO ratio
(0.5:1–2.5:1 w/w)on the product color was investigated in
the next series of experiments. In the experiment where the
pH value was varied, the color change was more pro-
nounced at pH 7, while the products obtained at pH 4
and5displayedcomparativelylowerΔE,of2.49and2.22,
respectively. This could be explained by the susceptibility to
the decomposition of citral at high pH and its stability in
acidic environments [14]. Apparently, at pH 5, the product
color changed to a minimal degree and thus was selected as
the condition for further investigation. Regarding color
change with respect to the added preservatives, the
base product incorporated with sodium benzoate dis-
played higher ΔE(1.75)when compared with those added
with sodium lactate (0.76)or with DMDM-H(0.77). There-
fore, DMDM-H and sodium lactate were used for further
experiments (Table 4).
The antioxidants are important ingredients that assist
in preventing and slowing down the oxidation process of
other chemicals in the formulation. They reduce the effects
of oxidation processes by binding to each other radical
molecules, reducing their decomposition power [32].In
the following experiments, the product color was investi-
gated with regard to the type of antioxidant and its con-
tent. Two common antioxidants, namely BHA and BHT,
were incorporated into the base formulation. The sample
incorporated with BHA and stored at 45°C demonstrated a
marked color quality change and major layering in the
bottle. On the contrary, samples incorporated with BHT
showed minor ΔEfluctuations and less color degradation
than BHA-containing samples. This is in part due to the
higher thermal stability of BHT structure in comparison
with BHA [33]. Thus, BHT was selected as the antioxidant
in the following experiment. Regarding the change of pro-
duct color with respect to the antioxidant/LEO ratio, a
higher ratio seemed to be associates with a more yellowish
Table 3: Color change of the washing product base after 7 days of
storage at 45°C formulated at different base oils and emulsification
conditions
Base oil Emulsification temperature (°C)Emulsifier ΔE
PEG-400 70 PEG-40 2.35
Paraffin oil 70 PEG-40 4.17
None 70 PEG-40 0.96
None Room PEG-40 1.54
None 50 PEG-40 1.58
None 60 PEG-40 1.13
None 70 PEG-40 1.26
None 80 PEG-40 1.75
None 90 PEG-40 1.83
None 60 Tween 80 1.98
None 60 Tween 20 4.31
None 60 PEG-40 1.73
None 60 None 0.87
Cosmetics formulation with lemongrass essential oil 825
product texture. However, the change was marginal and
could not be visually discernible. To be specific, at BHT/
LEO ratios of 0.5:1 and 1:1, the ΔEvalues of the base pro-
duct were 0.85 and 0.84, respectively. At higher BHT/ LEO
ratios of 1.5:1, 2:1, and 2.5:1, the color change progress was
more accelerated, reaching ΔEvalues of 1.6, 3.75, and 5.94,
respectively. The observed color degradation is largely
attributable to increased reactivity of the atmospheric
oxygen atoms having an uneven number of electrons in
the outer shell resulting in the chemical reactions occur-
ring within the base. The addition of BHT could contribute
to better color stability via a mechanism that is similar to
that of vitamin E. To be specific, BHT could donate one
hydrogen atom to the oxygen atoms with uneven electron
distribution, forming hydroperoxide [33]. However, exces-
sive addition of BHT may generate redundant electrons
than that required for radical oxygen to stabilize, adversely
affecting the product quality. From these results, the BHT/
LEO ratio of either 0.5:1 or 1:1 was used in subsequent
investigations.
3.3 Color and compositional changes of LEO
in formulated body wash and shampoo
products
The body wash and shampoo products incorporated with
LEO were stored for a month at 45°C. Sensorial examina-
tion of the samples shows that, compared with the initial
sample, the preserved products exhibit moderate color
change to light yellow and the aroma quality was com-
parable with those before storing. The ΔEvalues of the
body wash and shampoo after 1 month of storage were
1.13 and 0.85, respectively [34–37](Figure 3).
To elaborate on the degradation of the chemical com-
position of LEO after storage, different LEO samples were
analyzed by GC-MS. LEO was first recovered from the
products through a hydrodistillation process. Table 5
summarizes the compositions and contents of the com-
pounds in the bare LEO and LEO recovered from the
product base, body wash, and shampoo under different
storage times and temperatures. LEO isolated from the
Table 4: Color change of the washing product base after 7 days of storage at 45°C formulated at different process conditions
pH value Preservatives Antioxidants Antioxidant/LEO ratio (w/w)ΔE
pH 4 Sodium benzoate BHT 1:1 2.49
Sodium lactate
DMDM-H
pH 5 Sodium benzoate BHT 1:1 2.22
Sodium lactate
DMDM-H
pH 6 Sodium benzoate BHT 1:1 2.56
Sodium lactate
DMDM-H
pH 7 Sodium benzoate BHT 1:1 2.67
Sodium lactate
DMDM-H
pH 5 Sodium benzoate BHT 1:1 0.76
pH 5 Sodium lactate BHT 1:1 1.75
pH 5 DMDM-H BHT 1:1 0.77
pH 5 Sodium benzoate BHT 1:1 1.94
DMDM-H
pH 5 Sodium benzoate BHA 1:1 2.93
DMDM-H
pH 5 Sodium benzoate BHT 0.5:1 0.85
DMDM-H
pH 5 Sodium benzoate BHT 1:1 0.84
DMDM-H
pH 5 Sodium benzoate BHT 1.5:1 1.60
DMDM-H
pH 5 Sodium benzoate BHT 2:1 3.75
DMDM-H
pH 5 Sodium benzoate BHT 2.5:1 5.94
DMDM-H
826 Thien Hien Tran et al.
washing base, after 1 week and 1 month of storage, was
devoid of decomposition products of citral such as 3,7-
dimethyl-1,3,6-octatriene, p-1,5-menthadien-8-ol, and
p-cymen-8-ol. Other compounds such as isogeranial, ger-
aniol, cyclohexane, caryophyllene, α-bergamotene, buty-
lated hydroxytoluene, caryophylene oxide, m-camphorene,
and p-camphorene accounted for less than 1% of the total
content in the LEO sample recovered from the product base.
These results confirm the capability of the emulsification
technique for preserving the composition of essential oils
in the formulation of washing bases.
Regarding the citral content, the highest citral con-
tent was observed in the initial bare LEO and LEO after
7 days of storage at 45°C (86.89 and 86.28%, respectively),
closely followed by citral content in LEO recovered from
the body wash product (85.81 and 85.31% respectively).
Further comparison of the citral content in various pro-
ducts to that of the Initial bare LEO revealed that the
simulated product base stored after 1 month at 45°C
exhibited the highest citral reduction (around 9.7%).
Meanwhile, the corresponding values for the shampoo
and body wash product were only 4.9 and 1.8%, respec-
tively, suggesting that direct LEO incorporation into the
base may result in shampoo and body products with
minimized citral degradation. Some new ingredients in
shampoo and body wash with concentrations below 1%
included isogeranial, geraniol, cyclohexane, caryophyllene,
caryophylene oxide, m-camphorene, and p-camphorene.
The decrease in citral content or other ingredients is
due to the prolonged exposure to high temperatures
during the LEO recovery process. The increase of β-myr-
cene content in the base and the shampoo sample may be
Figure 3: Initial (1)and 1-month body wash product (2); initial (3)
and 1-month shampoo product (4).
Table 5: Chemical compositions of bare LEO, LEO recovered from the base sample, shampoo, and body products
No RT (min)Compounds Lemongrass oil Base sample Shampoo Body wash
Initial 7 days 1 month 7 days 1 month Initial 1 month Initial 1 month
1 9.813 6-Methyl-5-hepten-2-one 0.805 1.149 1.314 2.575 1.598 1.243 1.572 0.866 1.026
2 9.928 β-Myrcene 5.656 6.025 10.86 7.097 9.932 5.498 8.597 4.256 4.543
3 12.427 3,7-Dimethyl-1,3,6-octatriene ——0.395 —— —— — —
4 16.16 β-Linalool 0.754 0.664 0.805 1.818 0.775 0.959 0.808 0.839 0.788
5 18.942 Unknown name —0.727 0.232 0.197 0.224 —0.179
6 19.799 p-Mentha-1,5-dien-8-ol ——0.768 —— —— ——
7 20.667 p-Cymene-8-ol —0.288 1.154 —— —— ——
8 20.761 Isogeranial ——— 0.505 —0.295 0.826 —0.347
9 22.727 β-Citronellol 0.499 0.547 0.572 0.241 0.696 0.62 0.603 0.552 0.599
10 23.166 β-Citral 39.031 38.699 35.026 38.74 35.996 38.779 38.49 38.124 37.715
11 23.71 Nerol 3.887 3.583 3.612 2.601 4.306 4.294 4.249 3.831 4.277
12 23.773 Geraniol —0.4 0.429 —— 0.543 0.424
13 24.337 α-Citral 47.868 47.588 44.214 41.60 42.459 45.893 44.15 47.686 47.596
14 28.05 Geraniol acetate 0.602 0.361 0.525 1.125 0.889 0.45 0.851 0.329 0.784
15 28.227 Cyclohexane ——— —0.409 —0.366 0.369 0.784
16 29.419 Caryophyllene ——— 0.598 —0.412 0.621 —0.655
17 29.482 α-Bergamotene 0.267 0.309 0.324 —0.27 0.368 0.321 0.376 0.31
18 31.636 Butylated hydroxytoluene ——— —0.198 —— 1.735 —
19 33.226 Caryophylene oxide ——— 0.125 —0.123 0.091 —0.089
20 33.884 Selina-6-en-4-ol 0.115 0.2 0.189 —0.444 0.308 0.344 0.28 0.203
21 38.14 m-Camphorene ——— 0.289 0.266 0.314 —0.245 0.121
22 38.433 p-Camphorene ——— 0.181 —0.157 ———
23 39.552 Unknown name ——— 0.094 —0.079 ———
Citral content (%)86.899 86.287 79.24 80.34 78.455 84.672 82.64 85.81 85.311
% Citral decrease compared to initial −0.704 −8.814 −7.549 −9.717 −2.563 −4.903 −1.253 −1.827
Note: The values shown in bold in Table are due to (1)being the main ingredient in Lemon grass essential oil, (2)there is a marked variation
in content under different storage conditions.
Cosmetics formulation with lemongrass essential oil 827
attributable to its low molecular weight, making the com-
pound to be more susceptible to evaporation and in turn
more detectable during the GC-MS process. Alternatively,
the increased β-myrcene content could be attributed to the
rearrangement processes that transform surplus contents
such as citral, geraniol, and citronella [38]. The emergence
of substances such as geraniol, camphorene, and caryo-
phylene oxide, which were previously absent in the bare
LEO, could be explained by the inability of GC-MS to detect
the constituents at very low concentrations.
4 Conclusion
In this study, we attempted the incorporation of LEO into
the formulation of a washing product base, shampoo,
and body wash product. The process was optimized to
minimize color changes and citral degradation in the
final products. The incorporation of LEO into two cos-
metic products via direct mixing, rather than emulsion
forming with base oils or emulsifiers, gave products
better color stability. The best color stability of the pro-
duct base could be achieved by using the following for-
mulation conditions: pH, v5; preservatives, sodium lactate,
and DMDM-H; antioxidant, BHT; LEO/BHT ratio, 0.5:1 or 1:1
(w/w); temperature, 70°C. The obtained shampoo and body
wash also displayed negligible citral decomposition in com-
parisonwiththebareLEO.
Acknowledgements: Tran Thien Hien was funded by
Vingroup Joint Stock Company and supported by the
Domestic Master/ PhD Scholarship Programme of Vingroup
Innovation Foundation (VINIF), Vingroup Big Data Institute
(VINBIGDATA), code 2020.ThS.07.
Funding information: This work was funded by Vingroup
Joint Stock Company and supported by the Domestic
Master/Ph.D. Scholarship Programme of Vingroup
Innovation Foundation (VINIF), Vingroup Big Data
Institute (VINBIGDATA).
Author contributions: Thien Hien Tran, Cam Quyen Ngo
Thi, Tri Nhut Pham, Quynh Anh Phan Nguyen, and Kim
Ngan Tran Thi –investigation; Long Giang Bach and Le
Thi Hong Nhan –supervision; Thien Hien Tran –writing –
original draft.
Conflict of interest: The authors declare no conflict of
interest.
Data availability statement: The data that support the
findings of this study are available from the Nguyen Tat
Thanh University but restrictions apply to the availability
of these data, which were used under license for the cur-
rent study, and so are not publicly available. Data are
however available from the authors upon reasonable
request and with permission of the Nguyen Tat Thanh
University
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