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ABSTRACT: Partially hydrogenated soybean oil, referred to as
soywax, is gaining attention as a renewable and biodegradable
alternative to paraffin wax for use in candles. However, current
soywax candles suffer from several problems, especially poor
melting and solidification properties. Fully hydrogenated soy-
bean oil exhibits improved melting properties but owing to its
fragile texture, it is not yet acceptable in most candle applica-
tions. In the present work, KLX™ (a wax composed of fraction-
ated hydrogenated soy and cottonseed oils) was used as a base
material for candles, and the effects of additives such as hydro-
genated palm oil (HPO), FFA, and paraffin on the textural and
combustion properties were evaluated. Melting and solidifica-
tion profiles of KLX were better than those of fully hydrogenated
soy oil. Adding FFA improved the solidification properties of
KLX candles. Adding paraffin improved the compressibility of
the wax, while HPO addition decreased hardness and com-
pressibility. Changing the candle diameter and/or wick size
along with changing the wax composition resulted in candles
with desirable quality attributes.
Paper no. J10323 in JAOCS 79, 1241–1247 (December 2002).
KEY WORDS: Beeswax, candles, cottonseed oil, DSC, hydro-
genated oil, paraffin wax, soybean oil, soywax, texture analysis,
thermal imaging.
Overabundance in the world supply of vegetable oils and the
limited supply in petroleum resources provide impetus to the
candle industry to use waxes based on vegetable oils. The an-
nual U.S. market for paraffin in candle applications has been es-
timated at 1 billion pounds (1). This is equivalent to about 5%
(w/w) of the current soybean oil production in the United States.
Partially hydrogenated soybean oil, referred to as soywax,
has recently been used for manufacturing candles (2,3). Major
problems with soywax are the greasy surface texture and the
brittle structure of candles made of soywax. Also, poor melt-
ing and re-crystallization properties of soywax result in de-
layed re-solidification and therefore excessive dripping of the
wax. Consequently, the use of soywax has been limited to
container and large-diameter pillar-type candles. Proper hy-
drogenation of soybean oil may improve its melting and so-
lidification properties for use as candles.
The melting and re-solidification properties of the wax com-
ponents considerably influence the candle’s acceptability. Al-
though materials with lower m.p. create larger burning pools,
materials with unnecessarily low m.p. can cause uncontrolled
dripping of the candle wax with taper- and pillar-type candles.
Not only does this create a wax spillage problem, but also the
life of the candle is reduced and there may be a fire hazard as
well. Furthermore, the wick can be drowned and consequently
the flame can be extinguished in container-type candles.
Many small-scale candle-manufacturing companies are
applying the traditional methods of candle preparation. In re-
sponse to the growing demand for hand-crafted candles based
on hydrogenated vegetable oils, the number of these compa-
nies is also growing. In such operations, it is critical to avoid
cracking the candles during manufacturing. One approach to
reduce cracking is to disrupt the natural crystalline structures
of the waxes by adding other components whose presence in-
hibits crystal formation but does not interfere with the burn-
ing properties of the wax. Although large-scale industrial op-
erations (injection molding) may not involve the traditional
melting and pouring stages, problems associated with the re-
solidification of melted wax such as flowing liquid wax as a
result of improper composition of the waxes and/or channel-
ing (a phenomenon caused by a breakdown in the solid struc-
ture) need to be overcome.
To change melting, solidification, and/or crystallization
behaviors of vegetable waxes and to reduce the structural de-
ficiencies of candles, FFA, paraffin, and other vegetable oils
with different melting and solidification properties may be
added. We hypothesized that supplementing a properly hy-
drogenated vegetable oil product with an appropriate additive
can improve its melting and crystallization properties and re-
sult in better textural and combustion properties. Therefore,
the objective of this work was to evaluate the effects of FFA,
paraffin, and hydrogenated palm oil on the thermal, textural,
and burning properties of vegetable-based waxes.
EXPERIMENTAL PROCEDURES
Materials. Soft paraffin with a broad melting range (25–80°C)
and hard paraffin with two melting peaks at 32 (minor) and
49°C (major) were obtained from Dussek Campbell (Skokie,
IL), partially hydrogenated soywax (~20°C melting onset and
~39°C melting peak) from Cargill Co. (Minneapolis, MN),
and beeswax (35–65°C melting range) from Strahl & Pitsch,
Inc. (West Babylon, NY). Stearic acid [Pristerene 4910: ~59°C
m.p.; 0.5 iodine value (IV); FA composition of 2% C14:0, 28%
C16:0, and 64% C18:0]; KLX™ (a by-product of producing
confectionery fat, ~48°C melting peak; FA composition of
20% C16:0, 36% C18:0, and 44% C18:1); fully refined and par-
tially hydrogenated palm oil (HPO; 20–40°C melting range;
Copyright © 2002 by AOCS Press 1241 JAOCS, Vol. 79, no. 12 (2002)
*To whom correspondence should be addressed at Dept. of Food Science
and Human Nutrition, 2312 Food Sciences Bldg., Iowa State University,
Ames, IA 50011-1061. E-mail: tongwang@iastate.edu
Hydrogenated Vegetable Oils as Candle Wax
Karamatollah Rezaei, Tong Wang*, and Lawrence A. Johnson
Department of Food Science and Human Nutrition and Center for Crops Utilization Research,
Iowa State University, Ames, Iowa
FA composition of 45% C16:0, 6% C18:0, 45% C18:1, and 4%
C18:2); and fully hydrogenated soywax (melting peaks, 53 and
63°C; FA composition of 11% C16:0 and 89% C18:0) were pro-
vided, respectively, by Uniqema (Chicago, IL); Loders
Croklaan (Channahon, IL); Fuji Vegetable Oil, Inc. (Savan-
nah, GA); and C&T Refinery, LLC (Charlotte, NC). Candle
molds [2.2 ×19 cm (7⁄8×71⁄2in.) footed taper and 5.1-cm (2 in.)
and 8.9-cm (3.5 in.) diameter pillar], and thin and thick cotton
wicks (7.84 and 14.78 mg/cm, respectively) were purchased
from Pourette Manufacturing (Seattle, WA).
Candle preparation. Candle materials (100 and 300 g for
5.1- and 8.9-cm pillar candles, respectively) were melted in a
container to a maximum of 100°C. The melted wax was
stirred and allowed to cool to 80°C prior to transfer to the
mold. To avoid early solidification of the wax during the
pouring of beeswax candles and of candles having paraffin as
one of the components, the candles were cooled to and poured
at 90°C. A minimum of 6 h was allowed before the candles
were released from the molds. During the cooling stage,
paraffin candles incurred central voids in the vicinity of the
wick due to the strong adhesion of paraffin to the mold wall.
To fill these voids, additional melted paraffin wax was added
after initial cooling. Pure paraffin candles were composed of
a 50:50 ratio of soft/hard paraffins.
To evaluate the effects of added FFA in KLX, five differ-
ent FFA levels were selected (0, 5, 10, 25, 40, and 60%, w/w)
for use in 8.9-cm pillar candles with 14.78 mg/cm wicks. Soft
paraffin was incorporated at 0, 5, 10, and 20% (w/w) levels
to assess the effects of added paraffin. Similarly, 0, 10, 20,
and 40% HPO was used to evaluate the effects of added HPO
on candle properties.
On the basis of results from preliminary studies, wax con-
taining 60% FFA in KLX was selected to assess the effects of
candle diameter on burning characteristics. Two diameters
(5.1 and 8.9 cm) were used. Also on the basis of preliminary
experiments, 8.9-cm pillar candles with 25% FFA were se-
lected to assess the effects of wick size.
Temperature distribution on candle surface. Thermal
imaging (or so-called thermography) was used to measure the
temperature distribution profiles of candle surfaces.Ther-
mography is a non-contact, 2-D imaging system based on IR-
sensing of certain cameras (4,5). The 2-D images of the ob-
jects obtained this way are called thermograms (4,5). Ther-
mal images of the candles were recorded using an
Inframetrics™ PM250 ThermaCam™ (Flir Systems, North
Billerica, MA). Triplicate sets of candles were burned for 62
min, after which the flame was blown out and the image (top
view) was immediately recorded.
Melting and re-solidification properties. A differential
scanning calorimeter (DSC 6200, Seiko Instruments, Inc.,
Chiba, Japan) equipped with a cooling controller using liquid
nitrogen and an Exstar 6000 communication device (Seiko
Instruments Inc.) was used to measure the melting and re-
solidification behaviors of the waxes. Seiko Measurement
Software v. 5.8 and Seiko Analysis Software v. 5.5 (both from
Seiko Instruments Inc.) were used for data acquisition and
processing, respectively. A sample size of 7.00–15.00 mg was
used. The AOCS recommended practice Cj 1-94 (6) was
modified for temperature programming. An initial 2-min hold
at 30°C followed by 30°C/min ramping to 90°C and a sec-
ondary 10-min hold, and cooling to −40°C at 10°C/min and a
1-min hold, and a final heating step to 90°C at 10°C/min were
used for temperature programming. The first stage was for the
homogenization of the wax structure. Therefore, the last two
stages, comprising a cooling and a heating step, were used to
compile the major crystallization and melting peaks.
Hardness and compression measurements. A TA.XT2i
Texture Analyser™ (Stable Micro Systems, Ltd., Surrey,
United Kingdom) was used to characterize wax texture by
measuring hardness and compression forces. Prior to analy-
sis, the system was calibrated using a 5.0-kg standard weight.
By applying 2.0 mm/s pre-speed (the speed at which the
probe moved prior to contacting the sample), 0.1 mm/s speed
(the speed at which the probe penetrated the sample), and 0.1
mm/s post-speed (the speed at which the probe moved away
from the sample), and a 2.0-mm diameter probe, the total
force integrated for 2.0 mm of needle (probe) penetration was
measured and reported as hardness. A 5-N force was applied
to the probe penetrating from the top surface of the candles.
Two separate candles of 8.9-cm diameter were prepared for
each wax type, and triplicate measurements were made for
each candle (i.e., a total of 3 ×2 = 6 measurements for each
wax type).
Wax textures were also characterized by measuring the
force required to compress samples to 80% of their heights [a
method modified from those reported by Yang and Taranto
(7) and Antoniou et al. (8)]. Pillar candles (8.9-cm diameter)
were prepared by methods already described and then were
cut into pieces of 1.5-cm long ×1.0-cm high ×1.0-cm wide.
A 75-mm compression platen was used with the analyzer. To
avoid friction between the surfaces, both the probe and the
base were lubricated with soybean oil prior to each measure-
ment. Samples were compressed using these parameters: 2.0
mm/s pre-speed, 0.3 mm/s speed, and 0.3 mm/s post-speed;
the area integrated for the period was used for comparison.
The means of five measurements are reported.
Burn rate, pool diameter, and flame size measurements. To
measure the burn rates of the candles, three candles of each
wax composition were placed on a bench top and allowed to
burn for 6–7 h. Overall burn rate of each candle was obtained
by dividing the total weight loss during candle combustion
by the total burn time. Pool diameters of the foregoing can-
dles were also measured using a stainless steel ruler when ex-
actly 5 h of burning had elapsed. Comparison of the flame
sizes among different candle types was made by visual esti-
mation of the bulk of the flames when approximately 5 h of
burning had been completed.
FA composition. To determine the FA compositions of hy-
drogenated vegetable oils, 40–50 mg samples were esterified
by adding 1.0 mL sodium methoxide solution (1 M) and heat-
ing at 40°C for ~1 h. After esterification was complete, the
reagent was deactivated by adding several drops of water, and
1242 K. REZAEI ET AL.
JAOCS, Vol. 79, no. 12 (2002)
the FAME were extracted into 2.0 mL of hexane. The methyl
ester analysis was carried out using a Hewlett-Packard series
II model 5890 gas chromatograph equipped with an SP-2330
fused-silica column (30 m ×0.25 mm ×0.2 µm; Supelco,
Bellefonte, PA). Both the injection port and detector (FID)
were set at 230°C, and the oven temperature was set at 190°C.
A mixture of external standards was used to identify the chro-
matographic peaks.
Statistical analysis. The general linear model procedure of
the Statistical Analysis System (SAS) release 8.00 (SAS In-
stitute, Cary, NC) was used for data analysis (9). Means, least
significant differences (LSD), and error mean squares (EMS)
were determined.
RESULTS AND DISCUSSION
Currently, partially hydrogenated soywax (soft soywax) with
a FA composition of 11% palmitate, 12% stearate, 54%
oleate, and 22% linoleate is used in container- and pillar-type
candles. Because of its low melting and re-solidifying points
as observed by DSC (~20°C melting onset, 39.0°C melting
peak, and 22.0°C re-solidification peak), soft soywax melted
extensively, causing the wick to be drowned during the burn-
ing of container-type candles. For taper- and narrower pillar-
type candles, the liquid wax dripping from the candle did not
solidify fast enough to prevent the liquid wax from running
onto the bench. These problems stimulated us to evaluate
fully hydrogenated soybean oil (referred to as hard soywax,
~0 IV) for candle application. These candles were hard and
shiny with no surface greasiness at all. Furthermore, the melt-
ing and re-solidification properties were improved. DSC
analysis of hard soywax indicated two melting peaks at 52.8
and 63.0°C, and a solidification peak at 46.5°C. Compared to
a commercial paraffin candle (with minor and major melting
peaks at 40.6 and 59.0°C, respectively, and a re-solidification
peak at 49.7°C), the melting and re-solidification properties
of hard soywax were highly acceptable. However, the candles
had an unacceptably brittle texture and they did not fully melt
across the candle surface; therefore, they were not fully con-
sumed during combustion (even with taper candles).
To improve melting and crystallization properties and to
avoid brittleness of fully hydrogenated vegetable waxes, a
fractionated blend of hydrogenated soybean and cottonseed
oils (high trans content) was considered for the study. Such
product was commercially available as KLX, which was a by-
product (hardest fraction) in the production of fractionated
hard butter for confectionery applications and high-stability
cooking oils (10). Preliminary tests indicated that KLX was
suitable for candle applications.
Temperature distribution on candle surfaces. Typical ther-
mograms (top view) from the surfaces of the three different
candle types are shown in Figures 1A–C. The plots of tem-
perature abundance (i.e, the area percentage) for 240 data
points (0.42°C temperature increments) over a range of 20 to
120°C are shown in Figure 1D. Graphical presentations of
this type are referred to as thermal histograms. For KLX can-
dles, the Tmax (the temperature associated with the largest sur-
face area on the candle) in the melted zone is lower than those
of beeswax and paraffin, but in the unmelted zone, the Tmax is
higher than that of beeswax and similar to that of paraffin.
The colder liquid wax, in the case of burning KLX candles,
may be desirable for safety considerations.
The effects of FFA, paraffin, and HPO on the thermal pro-
files of candle surfaces were examined. Figures 2A and 2B,
respectively, illustrate the changes in peak temperature and
the surface thermal area% of the unmelted and melted zones
of the candles with different FFA, paraffin, and HPO contents.
With the addition of soft paraffin to KLX candles, the peak
temperatures in both melted and unmelted zones increased
(more in the melted zone). However, with increased HPO and
FFA levels, these changes were minimal. A large portion
(~60–85%) of the surface thermal areas of all candles was lo-
cated on the solid (unmelted) zone (Fig. 2B). With added
paraffin, the surface thermal area% of the melted zone de-
creased; however, with added HPO, this effect was opposite
and a desirable increase in the area% of the melted zone was
observed. A slight decrease in the area% of liquid zone was
observed with added FFA. These changes may be related to
the burning and melting properties and to heat conductivity
of different waxes as well as chemical and/or physical
interactions among the wax components. Surface imaging
analysis is a useful means to quantify the changes in the sur-
face temperature profile upon the addition of various wax
components.
Melting and re-solidifying properties. Typical DSC pro-
files for pure KLX and KLX with different FFA levels are
shown in Figure 3A. Although the melting properties of KLX
alone may be acceptable (peak at ~48°C), the low solidifica-
tion points (~30 and 23°C) render KLX unusable as a candle
wax for taper- or narrow (≤5.1-cm diameter) pillar-type can-
dles due to excessive dripping of the liquid wax. KLX candles
HYDROGENATED VEGETABLE OILS AS CANDLE WAX 1243
JAOCS, Vol. 79, no. 12 (2002)
FIG. 1. Histograms of various candle types. (A) KLX™ alone, (B) pure
beeswax (BSWX), (C) a 50:50 (w/w) mixture of soft and hard paraffin
(P50), and (D) comparison of temperature distributions among the three
types of candles.
(5.1- or 8.9-cm diameter) in pillar forms cracked during the
cool-down period in the molds and channeled during combus-
tion resulting in liquid melt flowing from the candles. Chan-
neling is the formation of a hole or a pathway in the wall
through which melted liquid wax flows. This defect was at-
tributed to weak structures resulting from non-uniform solidi-
fication of the wax during candle manufacturing.
The solidification peaks of KLX candles shifted to higher
temperatures with FFA addition (Fig. 3A), which was partly
due to the inherent FFA peak. The melting and solidification
peaks of pure FFA were 59 and 49°C, respectively. KLX with
60% FFA solidified at 46°C, which was considerably higher
than that of pure KLX (30°C). Such a change in the solidifi-
cation of the wax is desirable and can reduce problems asso-
ciated with wax dripping. On the other hand, the slightly ear-
lier melting of the wax due to the decrease in the m.p. from
48°C in pure KLX to 46°C in 60%-FFA KLX did not cause
any problems since the wax could still maintain its nongreasy
appearance.
The effects of paraffin and HPO additions were also exam-
ined. The soft paraffin had a wide melting range of 25–80°C.
Adding soft paraffin at 5, 10, and 20% to KLX resulted in a
shift in the melting and solidifying points (Fig. 3B). Slight in-
creases in both melting and solidifying points were observed
with the addition of 5% paraffin. However, more paraffin ad-
dition shifted them back to lower temperatures. Therefore,
there were no advantages in the use of paraffin to modify the
melting and solidifying properties of KLX. This along with
the increased cracking associated with paraffin addition makes
such modification undesirable. The addition of paraffin to hard
soywax was desirable for taper candles. A decline in the melt-
ing and solidifying points was observed as the HPO content
was increased (Fig. 3B), which makes the new compositions
less desirable for pillar candles. The DSC thermogram of HPO
indicated a major melting peak in the 25–40°C range, which
was far below that of KLX (~48°C).
Hardness and compression forces. Yang and Taranto (7)
and Antoniou et al. (8) used cohesiveness as a parameter to
characterize the textural properties of cheese, which were
measured by applying two consecutive compressions on sam-
ples at 80% of their heights and dividing the total area (force
×distance) for the second compression by the total area of the
first compression. However, in this study, due to the crumbli-
ness of KLX waxes, only the first compression at 80% of the
height was used and the total area for such compression was
also reported as compression. Furthermore, for paraffin and
beeswax, which were used as references, no compression
measurements were possible since the samples were so hard
and highly cohesive that the Texture Analyser was not able to
deform these samples to the dimensions of compressed KLX
waxes. Therefore, to compare KLX-based waxes with the ref-
erences, needle penetration was used to measure hardness.
The effects of FFA (5, 10, 25, 40, and 60%, w/w), paraffin
(5, 10, and 20%, w/w), and HPO (5, 10, 20, and 40%, w/w)
1244 K. REZAEI ET AL.
JAOCS, Vol. 79, no. 12 (2002)
FIG. 2. Changes in peak temperatures (A) and thermal surface areas (B)
of melted and unmelted zones of KLX candles with the addition of vari-
ous components obtained from thermal images. Tmax is the temperature
associated with the largest thermal surface area on the candle. HPO,
hydrogenated palm oil; PFN, soft paraffin.
FIG. 3. Effects of candle composition on melting and solidification pro-
files of waxes. (A) DSC thermograms for KLX candles at 0, 40, and 60%
FFA. (B) Changes in the melting and crystallization peaks of KLX waxes
with the addition of various components. For abbreviations see Figure 2.
additions on the texture of candles were evaluated using hard-
ness and compression analyses, which were obtained by inte-
grating the force used on a penetration needle and a compres-
sion platen, respectively (Fig. 4). The addition of FFA up to
25% did not significantly affect candle hardness. However,
candles with 40 and 60% FFA were significantly (P< 0.05)
harder compared to those with ≤25% FFA content. Compres-
sion, however, did not change significantly (P> 0.05) with
FFA addition (Fig. 4B). Compared to the variations in hard-
ness, variations in compression were somewhat higher (12.9
vs. 5.6% relative SD), which was related to texture inconsis-
tency within the candles as well as possible variations in the
dimensions of the cubes used for compression measurements.
Although adding FFA reduced the greasy texture of KLX
candles, the appearances of candles with 40 and 60% FFA
were not as desirable as those of the candles with ≤25% FFA
HYDROGENATED VEGETABLE OILS AS CANDLE WAX 1245
JAOCS, Vol. 79, no. 12 (2002)
FIG. 4. Effects of various additives on hardness (A) and compression (B) of KLX waxes. Within
each treatment, means with the same letter are not significantly different (P< 0.05). BSW:
beeswax; P50: a 50:50 (w/w) mixture of soft and hard paraffin; K05F, K10F, K25F, K40F, and
K60F: KLX with 5, 10, 25, 40, and 60% (w/w) FFA, respectively; K05P, K10P, K20P: KLX with
5, 10, and 20% (w/w) soft paraffin, respectively; Psoft: soft paraffin; K05H, K10H, K20H, and
K40H: KLX with 5, 10, 20, and 40% (w/w) partially hydrogenated palm oil (HPO), respec-
tively.
because the wax became more powdery. On the other hand,
candles with ≤25% FFA did not release well from the molds.
Both 40%- and 60%-FFA candles separated from their molds
during cooling. In fact, candles with 60% FFA had greater
shrinkage (i.e., better separation) than those made with 40%
FFA. In practice, a compromise between these two properties
needs to be made to achieve certain textural and burning
properties.
Figures 4A and 4B also show the changes in the hardness
and compressibility of KLX waxes with the addition of paraf-
fin. Although with an increase in paraffin content the hardness
was reduced, the products were more cohesive. Furthermore,
wax shrinkage during solidification was improved and the can-
dles were released easily from the mold. However, the candles
developed two or three cracks radiating from the candle center
to the circumference in the order 10% > 20% > 5% (beginning
with the most severe). Although these cracks did not interfere
with candle structure, their presence was an apparent defect.
The changes in the hardness and compressibility of KLX
waxes with added HPO are also shown in Figure 4. As HPO
content increased, both hardness (Fig. 4A) and compressibil-
ity (Fig. 4B) decreased, which were consistent with the more
greasy appearance and softer structure of the higher-HPO
candles. When making candles, none of the KLX candles
with added HPO released easily from the molds and candle
release had to be aided by heating the molds under hot water.
HPO candles were very soft and greasy. Error mean square
(EMS) and least significant difference (LSD) values for mean
comparisons are shown in Table 1.
Burning characteristics. Changes in burn rate and liquid
pool size were observed with the addition of FFA, paraffin,
and HPO (Figs. 5A,B). As FFA content increased, both burn
rate and pool size decreased. Changes in the burn rates are
shown over a 6–7 h burning period. Although the candles
made of pure KLX burned at 4.6 ± 0.4 g/h, the candles with
60% FFA burned at 2.8 ± 0.1 g/h, which was significantly dif-
ferent. Similarly, flame size decreased with added FFA. The
mean flame size of pure KLX candles was almost five times
that of candles containing 60% FFA. The mean burn rate of
paraffin candles (i.e., 50:50 mixture of soft and hard waxes)
was 5.0 ± 0.5 g/h, which was similar to that of KLX candles;
however, the mean burn rate of beeswax candles was 2.7 ±
0.8 g/h. Ooi and Ong (11) reported 8% greater candle life (i.e.,
a decrease in the burn rate) along with a smaller flame size
when 70% palm FA were added to paraffin candles. Changes
in the mean pool diameters for KLX candles with different
FFA levels are shown in Figure 5B. Candles made of pure
KLX developed a 6.7 ± 0.3 cm (diameter) liquid pool after 5
h of burning, whereas those made from KLX containing 60%
FFA created 3.9 ± 0.2 cm (diameter) liquid pools, which is
not desirable for pillar candles. This formulation, however,
may be better for narrower candles.
The effects of adding paraffin (5, 10, and 20%) on the
burning rate and the pool size of KLX candles are also shown
in Figures 5A and 5B. Burning rate was not significantly af-
fected by adding paraffin (P> 0.05). Adding soft paraffin to
KLX (up to 20%) increased the flame size by approximately
20–30%, which was consistent with the changes in the burn
rate. As was the case with adding FFA to KLX, soft paraffin
additions to KLX decreased the melt size (Fig. 5B). KLX had
a somewhat narrow melting peak, about 48°C (Fig. 3A).
However, soft paraffin had a wide melting range (beginning
at ~25°C and increasing to as high as 80°C), and as paraffin
content was increased, less wax was melted and a smaller liq-
uid melt was obtained.
1246 K. REZAEI ET AL.
JAOCS, Vol. 79, no. 12 (2002)
TABLE 1
Statistical Data for the Textural and Burning Properties
of Various Candles Studieda
Hardness (gs) Compression (gs) Burn rate (g/h)
Treatment EMS LSD EMS LSD EMS LSD
FFA 4.2·E6 2.3·E3 1.7·E9 5.5·E4 0.08 0.51
Paraffin 1.1·E6 1.2·E3 2.3·E9 6.7·E4 0.56 1.36
HPO 2.7·E6 1.8·E3 8.0·E8 3.1·E4 0.20 0.81
Diameter effect N/A N/A N/A N/A 0.02 0.44
Wick effect N/A N/A N/A N/A 0.05 0.52
aEMS, error mean square; LSD, least significant difference; HPO, hydro-
genated palm oil; NA, not applicable.
FIG. 5. Changes in the burning rate (A) and melt size (B) of KLX candles
with different added components. Insert is a comparison of images (top
view) of candles made of KLX alone (left) and KLX with 60% (w/w) FFA
(right) burned for 7 h. For abbreviations see Figure 2.
To understand how adding a low-melting component af-
fects the textural and burning properties of KLX candles, 0,
5, 10, 20, and 40% HPO addition was examined. No signifi-
cant changes (P> 0.05) in the burn rate were observed when
increasing the HPO content (Fig. 5A). However, a slight in-
crease in the melt size was observed as HPO content in-
creased from 10 to 20%, which was consistent with the melt-
ing properties of HPO (a wide peak at 20–40°C). EMS and
LSD values are shown in Table 1.
Effects of candle diameter and wick size. The effects of
candle diameter on surface temperature profiles and burn
rates were investigated by using 5.1- and 8.9-cm diameter
candles with 60% FFA in KLX. Surface temperatures of the
liquid zones in the 5.1-cm candles ranged from 67 to 90°C
and comprised 49% of the candle surface while those of the
8.9-cm candles ranged from 66 to 84°C and comprised only
21% of the total candle top surface. Tmax values for the solid
and liquid zones of the 5.1-cm candles were 53 and 74°C, and
those of the 8.9-cm candles were 38 and 72°C, respectively.
Because of the lack of wax beyond the candle area of 5.1-cm
candles, the heat remained around the candle center, which
indicated that the overall candle surface considerably influ-
enced the heat dissipation profiles. A hotter liquid wax, such
as those of the 5.1-cm candles, can be consumed easier dur-
ing the burning process, which was consistent with the burn
rates. The mean burning rates of the 5.1- and 8.9-cm diame-
ter candles made with 60%-FFA were 3.17 ± 0.23 and 2.79 ±
0.07, respectively.
To evaluate wick size effects, 25%-FFA KLX candles with
two different wick sizes were used. When Ooi and Ong (11)
studied the wick size effect, they used multiple wick strings
to increase the wick size. However, in this study, two wicks
of cotton strips having different thicknesses were used and
their masses for the unit length were used for specification
(7.84 mg/cm for thin wick and 14.78 mg/cm for thick wick).
There were major differences in the surface areas and Tmax
values for the melted and unmelted zones of the two types of
candles. The surface areas of the unmelted zone for the can-
dles with the thinner wick were larger (77%), for which a
lower Tmax value (31°C) was obtained. For the candles made
with the thicker wick, these values were 71% and 36°C, re-
spectively. Compared to candles made with the thicker wick,
smaller surface areas were obtained for the melted zone in
candles made with the thinner wick (17 vs. 25%). The Tmax
values for this zone were not different (72°C). At 25% FFA,
the burn rate of candles made with the thicker wick was sig-
nificantly (P< 0.05) higher than that of the candles made with
the thinner wick (3.55 ± 0.30 vs. 2.29 ± 0.11 g/h). Since the
consumption of wax was not limited by the supply of liquid
wax (i.e., more liquid wax was available than the amount con-
sumed), a larger amount of wax was withdrawn from the liq-
uid pool when a thicker wick was selected. The melted pool
size of the candles with thinner wicks after 5 h of burning was
smaller than those of candles with the thicker wicks (4.0 ± 0.2
vs. 5.5 ± 0.4 cm).
ACKNOWLEDGMENTS
This project was supported by Hatch Act and State of Iowa funds,
and a grant provided by the Iowa Soybean Promotion Board. The
authors would like to thank Dr. Hongwei Xin, professor, Agricul-
tural and Biosystems Engineering Department, Iowa State Univer-
sity, for his technical assistance in collecting thermal images. Also,
gratitude is expressed to C&T Refinery, LLC (Charlotte, NC),
Uniqema (Chicago, IL), ADM Randall Research Center (Decatur,
IL), Loders Croklaan (Channahon, IL), and Fuji Vegetable Oil, Inc.
(Savannah, GA) for providing fully hydrogenated soybean oil,
stearic acid, fully hydrogenated cottonseed oil, KLX, and hydro-
genated palm oil, respectively. Journal Paper no. J-19829 of the
Iowa Agriculture and Home Economics Experiment Station, Ames,
Iowa, Project no. 0178.
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[Received May 8, 2002; accepted August 23, 2002]
HYDROGENATED VEGETABLE OILS AS CANDLE WAX 1247
JAOCS, Vol. 79, no. 12 (2002)
