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Preparation and Characterization of Naturally Scented Candles Using
the Lemongrass (Cymbopogon сitratus) Essential Oil
Pham Hoang Danh1,2,*, Tri Nhut Pham1, Do Thi Kim Nga1,
Ngan Thi Thu Nhung1, Tri Duc Lam2, Tran Quoc Toan4,5
1NTT Hi-Tech Institute, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam
2Faculty of Chemical Engineering and Food Technology, Nguyen Tat Thanh University
3Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology, Ha Noi,
Vietnam
4Graduate University of Science and Technology, Vietnam Academy of Science and Technology,
Ha Noi, Viet Nam
Email: phdanh@ntt.edu.vn, labams2013@gmail.com
Keywords: Cymbopogon citratus, Lemongrass, Essential oil
Abstract. At present, there are many different forms of relaxation and aromatic candles are one of
the common forms. Scented candles not only provide background lighting but also help promoting a
feeling of wellness. This study attempts to produce scented candles from natural sources such as
soy wax, beeswax, and natural essential oils to bring the most practical benefits to the users. The
produced candle should be long lasting, low cost and causes no health effects. The composition of
scented candles included 60% beeswax, 30% soy wax, 8% lemongrass essential oil, 1% citric acid,
and 1% ethanol.
1. Introduction
Nowadays, Relaxation is considered as a process that relieves stress on your mind and body.
At present, there are many different forms of relaxation and aromatic candles are one of the
common forms. Scented candles play an important function in the health spas to relieve symptoms
of bronchitis, high blood pressure, tension, insomnia. In addition, scented candles provide holistic
approaches for relieving people of emotional and mental stress, grief, and trauma. Scented candles
contain additives taken from a variety of sources such as essential oils, herbs, spices, citrus, berries,
musk, oatmeal, and sea breeze. Today, scented candles are produced on an industrial scale from
petroleum sources such as paraffin and benzene homologies to create aromas which are potentially
harmful to human health [1-4]. Therefore, it is necessary to produce aromatic candles from natural
sources such as soy wax, beeswax, natural essential oils to bring the most practical benefits to the
users.
The principal object of the present study is to produce scented candles which yield pleasant
scent or odor. This is made possible by the use of a carrier or vehicle. These carriers are the sugars,
among which may be sucrose, dextrose, levulose, mannose, and glucose [5,6]. The present attempt
includes a method of making a scented and/or a colored candle which consists of (a) forming a
plurality of separate particles of candle wax; (b) combining the coloring and/or scenting agents with
these particles; (c) coating the particles with the selected agent or agents by agitating the particles
and agent(s) together; and (d) disposing the coated and dried particles in surrounding relation to a
candle wick. Various additives are used in candles to provide desirable qualities, such as color,
scent, texture, and stability [7-9]. The quantity of diluent required is the quantity necessary for
dissolving the fragrance or the antioxidant. Scented candles utilize a scent agent, typically an a
scented oil, that is added to the wax of the candle during manufacture and that releases a scent
during the burning of the candle. The scent may be provided in different concentrations for different
candles and a growing trend is to provide highly scented candles having a strong concentration of
Materials Science Forum Submitted: 2019-07-25
ISSN: 1662-9752, Vol. 977, pp 212-217 Accepted: 2019-08-09
doi:10.4028/www.scientific.net/MSF.977.212 Online: 2020-02-05
© 2020 Trans Tech Publications Ltd, Switzerland
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications Ltd, www.scientific.net. (#538787083, Linköpings Universitetsbibliotek, Linköping, Sweden-23/04/20,05:50:57)
the scenting agent. Fragrance-emitting candles are widely available and are typically employed to
impart odorant into space.
However, very few studies on the preparation of scented candles from beeswax, soy wax,
combined with self-distilled lemongrass essential oil [10-12]. The product is made entirely from
natural materials [13,14]. In addition, with the support of antioxidants, which help long-lasting
scented candles, the aroma is less variable during storage and transport.The objectives of this study
were to (i) investigate the parameters affecting the distillation process of lemongrass essential oil;
(ii) create a candle that has long lasting, no health effects, low cost; (iii) determine some
physicochemical properties and sensory evaluation of the product.The aroma and benefits of
aromatherapy show that human emotion adjusts, so the demand for aromatic candles is widespread.
And the use of candles to provide a variety of satisfying aesthetic effects of religious, festive or
relaxation.
2. Materials and Methods
2.1. Materials
Fresh lemongrass (Cymbopogon citratus) leaves were collected from Chau Thanh district, Long An
province. All lemongrass leaves were freshly cut. The leaves were rinsed with tap water to remove
soil and dust. Prior to use for essential oil extraction, the leaves were then cut into small pieces at
approximately 0,5-1 cm long each. The collected lemongrass leaves were kept in a sealed plastic
bag at ambient temperature and protected from the light. In order to improve recovery yield, the
leaves were soaked in deionized water for 30min before distillation. Na2SO4 anhydrous and citric
acid were from China with purity of 99%. Ethanol was from China with purity of 96%. Soybean
wax and beeswax were purchased at the 3C shop, made in the USA.
2.2. Hydrodistillation of lemongrass essential oil
Hydrodistillation was performed in a circulatory Clevenger-type apparatus (1L capacity) and
stopped after ensuring no more essential oil extracted. The maximum temperature of the system was
the boiling point of water and system was operated at atmospheric pressure. After distillation,
moisture was removed from the essential oil by adsorption. The essential oil was stored in a dark
container.
2.3. The mixing of scented candles
The soy wax and beewax is weighed sufficiently into the glass. Then melt the wax by boiling it at a
temperature of 70-80◦C. Following an appropriate amounts of antioxidant in the beaker, ethanol is
added, the mixture is dissolved. Turn off the stove and add the essential oil to the mixture, stirring.
Prepare the mold and pour the wax into the mold, let cool. The scented candles are finished.
2.4. Testing and characterization
We use Ohaus MB45 moisture analyzer to analyze the moisture content of the raw material. The
density of the essential oil was determined by Pycnometer method. The percentage yield of the
essential oil is calculated using the equation: yield = mass of essential oil (g)
mass of dry material (g) × 100.
Sensory evaluation of the hardness, color, odor, and appearance of scented candles was evaluated
by 20 volunteers using 5-point scales for each descriptor (1 is minimum and 5 is maximum of a
characteristic).
3. Results and Discussion
3.1. Hydrodistillation of lemongrass essential oil
Effect of water to lemongrass leaves ratio
Figure 1 displays the effect of different water to lemongrass leaves ratios on the essential oil yield.
We fixed the mass of lemongrass leaves and changed the volume of water. The results show the
Materials Science Forum Vol. 977 213
ratio of 3:1 has the optimal amount of essential oil. Water acts as a barrier to prevent overheating of
lemongrass leaves. However, higher water content can lead to delayed extraction since more
amount of heat is required to reach the boiling point of the water. At lower water content, the
burning of lemongrass leaves was observed indicating a deficiency of water during operation. The
measured moisture content of lemongrass leaves is 72.06%. Whereby, essential oil yield is 2.36 %.
Effect of distillation time
Figure 2 displays the effect of different distillation time on the essential oil yield. The results show
that when distillation time increased, the volume of essential oil obtained also increased. After 120
minutes, the volume of essential oil increased almost negligible. That is because the essential oil
was exhausted. So the optimum time is 120 minutes with the yield of 2.36%.
Figure 1. Effect of water to lemongrass leaves
ratio
Figure 2. Effect of distillation time
3.2. The mixing of scented candles
Effect of different waxes
Table 1. Effect of beeswax/soy wax ratio
Ratio
Characteristics
1:2
very soft, not
smooth
1:1
soft, smooth
2:1
hard, smooth
Table 1 shows the effect of different waxes on the hardness of candles. The results show that
soy wax is a relatively soft wax. So when using more soy wax, the candles are melting fast, not
beautiful and not preferred. Beeswax is high hardness. If only use beeswax, the aroma is not much.
So we mixed soy wax with beeswax. The optimum ratio is 2:1 (beeswax/soy wax). The candles
have smooth surface and hardness equivalent to candles sold on the market.
Effect of different antioxidants
Table 2. The different antioxidants were used in the experiment
Antioxidants
Citric acid
Oxalic acid
Quinol
Stearic acid
Fragrance
strong
weak
-
weak
Table 2 shows the effect of different antioxidants on the fragrance of candles. Ethanol is a
diluent that dissolves the antioxidant to form a solution containing antioxidants. The incorporation
of essential oil in candle wax is often difficult to ensure the release of a suitable level of fragrance
into the atmosphere. This is due to oxidation by flame or light. To overcome these limitations,
antioxidants can be used. Quinol is difficult to dissolve and change wax color, not satisfactory.
With oxalic acid and stearic acid, there is little or no odor since the fragrance is decomposed in part
or completely when burning. Citric acid protects the fragrance from oxidation by the flame of
214 Metal Materials Processes and Manufacturing
candles to diffuse into the surrounding environment. Chose citric acid as an antioxidant in scented
candles.
Effect of essential oil content
Table 3. Effect of essential oil content
Sample 1 2 3 4 5 6
Essential oil content
(%) 5 6 7 8 9 10
Fragrance barely
detectable weak weak strong strong very
strong
Table 3 shows the effect of essential oil content on the fragrance of candles. We fixed the
content of beeswax, soy wax, citric acid, and ethanol. The maintenance of fragrance is also
important during the candle manufacturing process, as that process involves heating the wax and
fragrance combination. Sample 1, 2, and 3 have little or no odor when burning in the room because
of low essential oil content. Samples 4, 5, 6 have a strong or very strong detectable
fragrance. Considering the economic value of candle manufacturing, the optimum essential oil
content of 8% is selected.
Effect of antioxidant content
Table 4. Effect of antioxidant content
Sample
1
2
3
4
5
Citric acid content
(%)
0.2 0.4 0.6 0.8 1
Fragrance
barely
detectable
weak weak moderate strong
Table 4 shows the effect of antioxidant content on the scented candles. The experiments also
pertain to a method for incorporating of fragrance and antioxidant into a candle wax containing
amounts of a diluent. The instant candle wax composition protects the fragrance candle from
undesirable changes occurring during both candle manufacture and burning. This is due to the
combination of heat, the presence of fragrance, and the requirement for ongoing capillary transport
of wax upward in the wick of the candle. In sample 1, 2, and 3, the low antioxidant content should
have little or no odor of the essential oil yielded in the flame, due to the oxidation of the odor
ingredients by the flame. Sample 4 has a moderate fragrance. In sample 5 which possess high
degrees of fragrance and has imparted incense to the atmosphere.
3.3. Product quality assessment
Sensory evaluation
Sensory evaluation of the hardness, color, fragrance before burning, and fragrance while burning
was conducted by 20 volunteers following a 1 to 5 scale for each descriptor (1 = totally disagree,
5 = totally agree). Figure 3 displays the mean numerical values of the sensory evaluation.
Materials Science Forum Vol. 977 215
Figure 3. The mean values of 20 volunteers in sensory evaluation
Hardness: Most users agreed (4.1 points). The product has the same hardness as candles in the
market because it is blended from two parts of beeswax and one part of soy wax.
Color: Beeswax and soy wax are white. Therefore, need to change the color to meet different
purposes. Particularly colorants such as oil-soluble dyes and pigments permitting the achievement
of desired color effects. The color content used is not more than 0.05%. The users almost agreed
(3.7 points).
Fragrance before burning: Most respondents were able to clearly notice the fragrance of
lemongrass (4.3 points). Smelly essential oil has a strong and features odor, so antioxidant protects
the fragranced candle from undesirable changes occurring during its manufacture and storage.
Fragrance while burning: the natural fragrance of lemongrass essential oil is employed to
impart odorant into space. The odorant will mask other odors, or simply impart its own, in order to
make a space more pleasant. Most users thought that the fragrance had a slight decrease compared
to before burning (4.15 points).
Burning properties
Scented candles are tested for burning properties including flame height, burning time, smoke and
compared with scented candles in the market. The comparative results are presented in Table 5.
Table 5. Comparison between prepared scented candles and commercial scented candles
Properties
Prepared scented candles
Commercial scented candles
Flame height (cm)
3.4
7.2
Burning time (min)
120
60
Smoke
a little when extinguished
plenty of black smoke
Figure 4. (A) Prepared scented candles and (B) Commercial scented candles
216 Metal Materials Processes and Manufacturing
Both the prepared and commercial scented candles have the same candle height, diameter,
and length of wick. Both samples have almost the same hardness. The results show that commercial
candles have a higher flame, leading to faster burning time. Prepared candles produced lower flame
and longer burning time. In addition, commercial candles burn with more black smoke than
prepared candles. This is due to commercial candles are made from the wax has a low melting
point, in turn leading to quick evaporation. The wax of commercial candle is also observed to be
impure, so it creates more black smoke while burning.
4. Conclusion
This study attempted the manufacture of precursor aromatic candles from natural herbs. The
composition of scented candles has also been researched included 60% beeswax, 30% soy wax, 8%
lemongrass essential oil, 1% citric acid, and 1% ethanol. The antioxidant is effective in preventing
undesired changes in manufacture, storage, and burning.
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