International Food Research Journal 18: 213-220 (2011)
The properties of jelly candy made of acid-thinned starch
supplemented with konjac glucomannan or psyllium husk powder
Habilla, C., Sim, S.Y., Nor Aziah. and *Cheng, L.H.
Food Technology Division, School of Industrial Technology, Universiti Sains
Malaysia, 11800 Minden, Penang, Malaysia
Abstract: In this study, acid-thinned starch was blended with konjac glucomannan or psyllium husk powder
at a concentration of 3% w/w (starch basis). The blends were characterized by pasting analysis and rheological
properties evaluation. Jelly candy was made from the blends and textural characteristics were studied. Pasting
analysis showed that both gums were found to significantly increase some of the pasting parameters, such as
peak viscosity, trough, breakdown, final viscosity and setback values. From the frequency sweep, it was found
that addition of konjac glucomanan or psyllium husk powder increased the storage modulus (G’) and loss
modulus (G’’) values, with psyllium added sample showing more prominent effect than konjac added ones,
when compared to the control samples. All samples were found to demonstrate thixotropic flow behaviour. Jelly
candy texture profile analysis revealed that konjac glucomannan or psyllium husk powder addition, although
decreasing chewability, but rendered the jelly candy less sticky.
Keywords: starch, psyllium husk, konjac glucomannan, jelly candy
Introduction
Chewy candies are made with different gelling
agents and sweeteners that offer characteristic textures
and eating properties. The most common chewy
candies besides chewing gums are jellies, caramels,
nougats and taffies. The vast variety available was
invented and developed by confectioners through
trial and error without proper investigation. That is
why; candy making is commonly recognized as an art
rather than as a science, henceforth it is not surprising
that literature on candy is relatively scarce.
Jelly candy prepared with acid-thinned starch
has a tender yet firm texture. Acid-thinned starch
was commonly used due to its high gel strength
and capability in inducing rapid set upon cooling
(Thomas and Atwell, 1999). Nevertheless, there are
problems which are inherent to starch-based foods
such as retrogradation, syneresis, and loss of original
texture (Ferrero et al., 1996). This can be overcome
by blending with hydrocolloids (gums or proteins),
which are believed to be able to improve food texture,
retard starch retrogradation, enhance moisture
retention and overall keeping quality (Stauffer,
1990; Gujral et al., 2004; Lim and Narsimhan, 2006;
Muadklay and Charoenrein, 2008; Pongsawatmanit
and Srijunthongsiri, 2008; Anton et al., 2009; Tian
et al., 2009). In this project, the gums selected to
be incorporated into starch-based jelly candy were
psyllium husk powder and konjac glucomannan.
Psyllium hydrophilic mucilloid, is a natural fiber
derived from psyllium seed husks. It is a highly
branched arabinoxylan polysaccharide which has a
high water holding and gelling capacity (Anderson et
al., 1990). Nowadays, psyllium seed husks are mostly
used as dietary supplement to treat constipation,
hypercholesterolemia, and for daily colon care
(Gerber, 1996; Greenwald et al., 2001; Terry et al.,
2001).
On the other hand, konjac glucomannan is a
neutral polysaccharide derived from the tubers of
Amorphophallus konjac. It is an indigestible dietary
fiber which helps in weight reduction, cholesterol
reduction, and modification of carbohydrate
metabolism in diabetics (Imeson, 1997). It was
reported to be able to bind bile acids in the gut and
carry them out of the body in the faeces thus indirectly
making the body converting more cholesterol into
bile acids (Wu and Peng, 1997).
To the best of our knowledge, there has been no
study conducted to study the addition effect of psyllium
or konjac glucomannan on the characteristics of jelly
candies despite the fact that, both hydrocolloids have
great benefits in terms of nutrition and functional
properties. Therefore, this work was devised to study
the changes in pasting and rheological properties of
acid-thinned starch suspension and paste, respectively.
In addition, the keeping quality of the jelly candy
*Corresponding author.
Email: lhcheng@usm.my
Tel: +604-6532118, Fax: +604-6573678
© All Rights Reserved
214 Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
International Food Research Journal 18: 213-220
supplemented with psyllium or konjac glucomannan
were evaluated.
Materials and Methods
Materials
Acid-thinned starch (Elastigel 1000 J) was
purchased from National Starch and Chemical (M)
Sdn. Bhd. (Selangor Darul Ehsan, Malaysia). Konjac
glucomannan (KGM) was obtained from Hung Thong
Food Technology Sdn. Bhd. (Penang, Malaysia).
Psyllium husk (Plantago ovata) (Natural Psyllium
Husk, 99.29% purity) was bought from Country
Farms Sdn. Bhd. (Selangor, Malaysia). Sugar, corn
starch, Tri-sodium citrate, dextrose, citric acid,
flavoring agents and coloring agents were obtained
from SIM Company Sdn. Bhd. (Penang, Malaysia).
Pasting properties
A Rapid Visco Analyzer (Model RVA Series 4,
Newport Scientific Pty. Ltd, Warriewood, Australia)
was used to determine the apparent viscosity of starch
or starch-hydrocolloid suspension. About 5 g of acid-
thinned starch (corrected for 14% moisture basis) was
mixed with distilled water in an aluminium canister.
Sample without hydrocolloid addition was designated
as control. For sample added with hydrocolloid i.e.,
konjac glucomannan or psyllium husk powder was
designated as konjac or psyllium added herein. The
level of addition was 3% w/w on starch basis. The
starch-hydrocolloid blends were pasted according
to a programmed heating and cooling cycle: Sample
was first agitated at 960 rpm for 10 sec to impart
thorough dispersion, following with holding at 50ºC
for 1 min, heating from 50ºC to 95ºC at 12ºC/min and
160 rpm, holding at 95ºC for 2.5 min before cooling
to 50ºC at the same stirring rate and lastly holding at
50ºC for 2 min. Pasting parameters such as pasting
temperature, peak viscosity, trough, breakdown, final
viscosity and setback were determined.
Rheological properties
Rheological evaluation was performed using a
rheometer (Model AR 1000, TA Instruments Inc.,
New Castle, DE, United States). Samples used were
those which had been subjected to pasting analysis.
Frequency sweep ranged from 0.01 to 10 Hz was
performed at 25°C and at 1% strain which was pre-
determined from the linear viscoelastic region of the
sample. The geometry used was a 20 mm standard
parallel plate and the gap size was fixed at 1000 μm.
To avoid evaporation, paraffin oil was wiped over the
sample edge. TA Rheologist Data Analysis software
(Version 5.4.8) was used to obtain the experimental
data and to determine storage modulus (G’) and loss
modulus (G’’).
Stepped flow curves were obtained by recording
shear stress values when samples were subjected
to a programmed shear rate increased linearly from
0 to 1000 s
-1
and decreased linearly from 1000 to
0 s
-1
, respectively. All measurements were carried
out at 50°C using a parallel plate geometry (40 mm
diameter and 1 mm gap).
Making of jelly candy
Three recipes for starch-based jelly candy
preparation are shown in Table 1. Acid-thinned
starch (Elastigel 1000J) suspension was cooked until
Table 1. Ingredients needed to make jelly candies
Ingredients
Control
Konjac added
Psyllium added
Glucose syrup (42 DE) (g)
360.0
360.0
360.0
Sugar (g)
300.0
300.0
300.0
Dextrose (g)
110.0
110.0
110.0
Acid-thinned starch (g)
100.0
100.0
100.0
Konjac glucomannan (g)
-
3.0
-
Psyllium husk (g)
-
-
3.0
Water (for starch) (g)
550.0
550.0
550.0
Warm water (for citric acid) (ml)
20.0
20.0
20.0
Tri-sodium citrate (g)
4.0
4.0
4.0
Citric acid (g)
4.0
4.0
4.0
Flavoring (g)
1.0
1.0
1.0
Coloring (drop)
1
1
1
Acid thinned starch
International Food Research Journal 18: 213-220
Table 2. Pasting properties of acid-thinned starch added with or without konjac glucomannan or psyllium husk.
Pasting Properties
Control
Konjac added
Psyllium added
Pasting Temperature (
o
C)
77.85 ± 0.43a
78.82 ± 0.51b
77.27 ± 0.23a
Peak Viscosity (RVU)
57.14 ± 0.88a
80.25 ± 3.71b
132.22 ± 3.80c
Trough (RVU)
12.45 ± 0.54a
19.08 ± 3.90b
32.05 ± 6.76c
Breakdown (RVU)
44.69 ± 0.76a
61.17 ± 1.94b
100.17 ± 4.46c
Final Viscosity (RVU)
270.50 ± 9.83a
300.94 ± 12.31b
448.47 ± 37.01c
Setback (RVU)
213.36 ± 9.16a
220.70 ± 12.38a
316.25 ± 35.61b
Table 3. Best-fitted parameters of Herschel-Bulkley model for acid-thinned starch suspension with or without
added konjac or psyllium
Upward curve Downward curve
index
Note: Mean ± standard deviation of triplicate samples. Values followed by the same letter in the same column are not significantly
different (P>0.05).
Figure 1. Variation of storage modulus (G’) and loss modulus (G”) as a function of frequency
Sample
Yield stress
(Pa)
Consistency
index (Pa.s)
Flow
behaviour
index
Yield
stress (Pa)
Consistency
index (Pa.s)
Flow
behaviour
Thixotropic area
( Pa/s )
Control 1.10±1.13a
0.13±0.14a
0.74±0.10b 0.74±0.48a
0.08±0.01a
0.83±0.12a
740.20±180.12a
KGM
added
0.47±0.12b
0.06±0.02b
0.85±0.01a 0.60±0.26a
0.08±0.03a
0.84±0.01a
290.23±55.14b
Psyllium
added
0.41±0.16b
0.12±0.05a
0.77±0.03b 0.12±0.03b
0.04±0.02b
0.84±0.05a
807.70±177.54a
216 Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
International Food Research Journal 18: 213-220
Figure 2. Flow behaviour of acid-thinned starch suspension with or without konjac or psyllium added.
Figure 3. Storage effects on Texture Profile Analysis parameters of different jelly candy prepared.
Acid thinned starch
International Food Research Journal 18: 213-220
a clear paste was evident. Where necessary, konjac
glucomannan or psyllium powder was pre-mixed
with a portion of sugar prior adding into the mixture.
After two minutes boiling, glucose syrup was added
together with the remaining sugar and dextrose. The
mixture was cooked with continuous stirring until a
soluble solid content of 65 ºBrix was reached. Lastly,
heat was turned off, and citric acid solution, colouring
and flavouring agents were added. The suspension
was then cast into pre-dried corn starch mould
while it was still hot and free flowing. The cast jelly
samples were then tempered at 65ºC for 24 hours.
Sample preparation was duplicated and samples were
stored in air tight container at 30°C and withdrawn
at 0, 4 and 8 weeks for texture profile analysis. The
abovementioned method was modified from National
Starch & Chemical Company’s technical notes for
jelly candy making.
Texture profile analysis (TPA)
Texture profile analysis (TPA) was performed
directly on jelly candies of specific and consistent
dimension at ambient temperature with a TA-XT Plus
Texture Analyzer (Stable Micro Systems, Surrey,
England) using a cylindrical 75 mm diameter probe
and a 30 kg load cell. Measurements were conducted
at a pre-test speed of 1.0 mm/s, a post-test speed
of 10.0 mm/s, a test speed of 2.0 mm/s, and 20 g
trigger force. Deformation level was fixed at 75%.
Five sub-samples from each sample preparation were
analyzed.
Statistical analysis
Statistical analysis was carried out using
statistical software SPSS 14.0 for windows (SPSS,
Inc., Chicago, IL, USA). Where necessary, One-
way ANOVA and Duncan’s test were conducted at a
significant level of P < 0.05.
Results and Discussion
Pasting properties
Pasting properties of acid-thinned starch
suspension with or without added konjac or psyllium
are reported in Table 2. The pasting temperature
was slightly increased with konjac addition and
no significant difference was evident for psyllium
added sample. Significant differences (P<0.05) were
recorded in peak viscosities, highest values was shown
by psyllium added sample (132.22 RVU), followed by
konjac added (80.25 RVU) and control (57.14 RVU).
This shows that a higher viscous load would likely
to be encountered during cooking of the acid thinned
starch suspension with added konjac or psyllium. Such
a phenomenon could be attributed to the thickening
effect of konjac or psyllium, or alternatively due to
interactions happened between gums and swollen
starch granules (Rojas and Rosell, 1999) or leached
molecules, i.e. amyloses and amylopectins (Shi and
BeMiller, 2002; Funami et al., 2005). On the other
hand, the gums may provide additional cushion effect
to swollen granules to facilitate radial expansion till a
maximal swelling capacity is reached.
A higher breakdown value was shown in konjac
or pysllium added samples. This value was calculated
as the difference between peak viscosity and trough
value. Therefore, if the difference in trough values
is marginal, the higher the peak viscosity, the higher
the breakdown would be recorded. A high breakdown
was related to a sample structure that is relatively
weaker or less resistant to shearing during heating
(Lee et al., 2002).
On cooling, a relatively higher final viscosity and
setback values were also shown by konjac or psyllium
added sample. This can be attributed to thickening
effect of each gum in addition to amylose gelation.
According to the work of Alloncle et al. (1989) and
Yoshimura et al. (1998), it was suggested that an
increase in the effective concentration of starch in
the continuous phase could result in an enhanced
interaction between amylose molecules. It is the
thermodynamic incompatibility between amylose
and konjac, and amylose and psyllium polymers
that leads to mutual exclusion of each polymers and
as a result the local increase in concentration could
facilitate molecules rearrangement and association
(Allonce and Doublier, 1991; Funami et al., 2005).
Rheological measurements
Frequency sweep. Figure 1 depicts changes
of storage modulus (G’) and loss modulus (G”) of
jelly slurries prepared as a function of frequency.
In general, a plateau-like graph of G’ indicates the
presence of network structures (Kulicke et al., 1996).
For all samples, G’ is predominated over G” and G”
increased with increasing frequency, indicating that
all samples show gel-like behaviour (Steffe, 1996).
From the mechanical spectra, it is clearly evident that
psyllium added sample possesses a higher G’, hence
it is more elastic or solid-like than konjac added
and control samples, which may be attributed to a
more cohesive network formed among and between
psyillium and starch molecules. This observation
agrees with those high final viscosity and setback
values reported in previous analysis on pasting
properties.
Stepped flow analysis. As expected, all samples
demonstrated a non-Newtonian shear thinning
rheological behaviour (Figure 2). The hysteresis loop
218 Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
International Food Research Journal 18: 213-220
shown between the ramp up and ramp down curves
indicates that the sample flow was time-dependent.
The size of the hysteresis loop is related to the
energy needed to destroy the structure responsible
for flow time dependence (González-Tomáz et al.,
2007). Therefore, the higher the loop area, the more
structured the material.
Comparing the three samples tested, the flow
curves of psyllium added sample was significantly
shifted upwards implying that a relatively higher
shear stress is needed to affect a unit flow in psyllium
added sample as compared to the others. Result
tabulated in Table 3 clearly depicts that konjac
added sample shows two to three times smaller
thixotropy value. This suggests that konjac may have
significantly weakened the network structure of starch
molecules, and rendered the blend easier to deform
and recover upon removal of shearing load. This in
turn explains why lower yield stress and consistency
values together with a higher flow behaviour index
were evident in sample added with konjac. From the
lower yield stress values, it can be anticipated that
jelly slurry supplemented with konjac or psyllium is
easier to be pumped from the cooker for deposition.
Texture profile analysis (TPA)
The changes of hardness, cohesiveness,
chewiness, and adhesiveness of jelly candies prepared
are illustrated in Figure 3. The hardness of fresh jelly
candy samples tested were found to decrease with
addition of konjac or psyllium , but it progressively
increased as the samples were stored for 8 weeks at
30°C. The reverse trend was observed for samples
cohesiveness. According to Szczesniak (2002),
hardness and cohesiveness were defined as the force
required attaining a given deformation and the extent
to which a material can be deformed before it ruptures,
respectively. Hence, these observations suggest that
konjac and psyllium are effective in delaying short-
term retrogradation. Our result is in line with the
work of Funami et al. (2005), which reported that
when galactomannan was added to wheat starch, the
dynamic mechanical loss tangent of the blend was
found to increase during short-term retrogradation,
showing that the gelled fraction has been reduced
upon addition of gums through inhibition of amylose
gelation.
However, for long-term storage post gelation
structural rearrangement was accelerated in the
presence of konjac or psyllium. Previous explanation
may be probably hold here, where the polymer
exclusion effect has expedited the retrogradation
process between amylose and amylopectin molecules.
Consequently, a highly rearranged or organized starch
gels resulted and the texture became harder and less
deformable upon long-term storage.
On the other hand, chewiness which is defined
as the energy required masticating a solid food to a
state ready for swallowing (Szczesniak, 2002), was
shown to increase with storage time, however the
intensity of increment is reduced substantially upon
addition of konjac or psyllium. This is consistent with
the result of springiness (data not shown), at which
a less springy gels were demonstrated by konjac or
psyllium added jelly candies. In other words, konjac
and psyllium addition rendered the acid-thinned
starch jelly less chewable.
As evident in Figure 3, the attributes of
adhesiveness was not shown in all fresh samples, but
it appeared after storage. It increased significantly
higher in the control samples than gums added
ones. This indicates that konjac or psyllium helps to
enhance the water holding capacity of acid-thinned
starch jelly candy.
Conclusions
This study showed that konjac and psyllium at
relatively small amount can modify the physical
performance of acid-thinned starch in jelly candy
production. From the results obtained, though konjac
or psyllium was found to produce a higher viscous
starch suspension during cooking, the jelly slurry
prepared can be pumped easily during deposition
with a relatively lower yield stress value, when
compared with the control sample. Apart from this,
gums addition enhanced the water holding capacity
of acid-thinned starch jelly candy. Overall, the jelly
candy quality characteristics supplemented with
konjac or psyllium were found to be acceptable with
reduced stickiness.
Acknowledgements
This work was supported by a short-term grant
(Grant No.:304/PTEKIND/638019) and USM
Fellowship scheme funded by Universiti Sains
Malaysia.
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Preview text:

International Food Research Journal 18: 213-220 (2011)
The properties of jelly candy made of acid-thinned starch
supplemented with konjac glucomannan or psyllium husk powder
Habilla, C., Sim, S.Y., Nor Aziah. and *Cheng, L.H.
Food Technology Division, School of Industrial Technology, Universiti Sains
Malaysia, 11800 Minden, Penang, Malaysia
Abstract: In this study, acid-thinned starch was blended with konjac glucomannan or psyllium husk powder
at a concentration of 3% w/w (starch basis). The blends were characterized by pasting analysis and rheological
properties evaluation. Jelly candy was made from the blends and textural characteristics were studied. Pasting
analysis showed that both gums were found to significantly increase some of the pasting parameters, such as
peak viscosity, trough, breakdown, final viscosity and setback values. From the frequency sweep, it was found
that addition of konjac glucomanan or psyllium husk powder increased the storage modulus (G’) and loss
modulus (G’’) values, with psyllium added sample showing more prominent effect than konjac added ones,
when compared to the control samples. All samples were found to demonstrate thixotropic flow behaviour. Jelly
candy texture profile analysis revealed that konjac glucomannan or psyllium husk powder addition, although
decreasing chewability, but rendered the jelly candy less sticky.
Keywords: starch, psyllium husk, konjac glucomannan, jelly candy Introduction
psyllium husk powder and konjac glucomannan.
Psyllium hydrophilic mucilloid, is a natural fiber
Chewy candies are made with different gelling
derived from psyllium seed husks. It is a highly
agents and sweeteners that offer characteristic textures
branched arabinoxylan polysaccharide which has a
and eating properties. The most common chewy
high water holding and gelling capacity (Anderson et
candies besides chewing gums are jellies, caramels,
al., 1990). Nowadays, psyllium seed husks are mostly
nougats and taffies. The vast variety available was
used as dietary supplement to treat constipation,
invented and developed by confectioners through
hypercholesterolemia, and for daily colon care
trial and error without proper investigation. That is
(Gerber, 1996; Greenwald et al., 2001; Terry et al.,
why; candy making is commonly recognized as an art 2001).
rather than as a science, henceforth it is not surprising
On the other hand, konjac glucomannan is a
that literature on candy is relatively scarce.
neutral polysaccharide derived from the tubers of
Jelly candy prepared with acid-thinned starch
Amorphophallus konjac. It is an indigestible dietary
has a tender yet firm texture. Acid-thinned starch
fiber which helps in weight reduction, cholesterol
was commonly used due to its high gel strength
reduction, and modification of carbohydrate
and capability in inducing rapid set upon cooling
metabolism in diabetics (Imeson, 1997). It was
(Thomas and Atwell, 1999). Nevertheless, there are
reported to be able to bind bile acids in the gut and
problems which are inherent to starch-based foods
carry them out of the body in the faeces thus indirectly
such as retrogradation, syneresis, and loss of original
making the body converting more cholesterol into
texture (Ferrero et al., 1996). This can be overcome
bile acids (Wu and Peng, 1997).
by blending with hydrocolloids (gums or proteins),
To the best of our knowledge, there has been no
which are believed to be able to improve food texture,
study conducted to study the addition effect of psyllium
retard starch retrogradation, enhance moisture
or konjac glucomannan on the characteristics of jelly
retention and overall keeping quality (Stauffer,
candies despite the fact that, both hydrocolloids have
1990; Gujral et al., 2004; Lim and Narsimhan, 2006;
great benefits in terms of nutrition and functional
Muadklay and Charoenrein, 2008; Pongsawatmanit
properties. Therefore, this work was devised to study
and Srijunthongsiri, 2008; Anton et al., 2009; Tian
the changes in pasting and rheological properties of
et al., 2009). In this project, the gums selected to
acid-thinned starch suspension and paste, respectively.
be incorporated into starch-based jelly candy were
In addition, the keeping quality of the jelly candy *Corresponding author. Email: lhcheng@usm.my © All Rights Reserved
Tel: +604-6532118, Fax: +604-6573678 214
Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
supplemented with psyllium or konjac glucomannan
for 1 min, heating from 50ºC to 95ºC at 12ºC/min and were evaluated.
160 rpm, holding at 95ºC for 2.5 min before cooling
to 50ºC at the same stirring rate and lastly holding at
Materials and Methods
50ºC for 2 min. Pasting parameters such as pasting
temperature, peak viscosity, trough, breakdown, final Materials
viscosity and setback were determined.
Acid-thinned starch (Elastigel 1000 J) was
purchased from National Starch and Chemical (M)
Rheological properties
Sdn. Bhd. (Selangor Darul Ehsan, Malaysia). Konjac
Rheological evaluation was performed using a
glucomannan (KGM) was obtained from Hung Thong
rheometer (Model AR 1000, TA Instruments Inc.,
Food Technology Sdn. Bhd. (Penang, Malaysia).
New Castle, DE, United States). Samples used were
Psyllium husk (Plantago ovata) (Natural Psyllium
those which had been subjected to pasting analysis.
Husk, 99.29% purity) was bought from Country
Frequency sweep ranged from 0.01 to 10 Hz was
Farms Sdn. Bhd. (Selangor, Malaysia). Sugar, corn
performed at 25°C and at 1% strain which was pre-
starch, Tri-sodium citrate, dextrose, citric acid,
determined from the linear viscoelastic region of the
flavoring agents and coloring agents were obtained
sample. The geometry used was a 20 mm standard
from SIM Company Sdn. Bhd. (Penang, Malaysia).
parallel plate and the gap size was fixed at 1000 μm.
To avoid evaporation, paraffin oil was wiped over the
Pasting properties
sample edge. TA Rheologist Data Analysis software
A Rapid Visco Analyzer (Model RVA Series 4,
(Version 5.4.8) was used to obtain the experimental
Newport Scientific Pty. Ltd, Warriewood, Australia)
data and to determine storage modulus (G’) and loss
was used to determine the apparent viscosity of starch modulus (G’’).
or starch-hydrocolloid suspension. About 5 g of acid-
Stepped flow curves were obtained by recording
thinned starch (corrected for 14% moisture basis) was
shear stress values when samples were subjected
mixed with distilled water in an aluminium canister.
to a programmed shear rate increased linearly from
Sample without hydrocolloid addition was designated
0 to 1000 s-1 and decreased linearly from 1000 to
as control. For sample added with hydrocolloid i.e.,
0 s-1, respectively. All measurements were carried
konjac glucomannan or psyllium husk powder was
out at 50°C using a parallel plate geometry (40 mm
designated as konjac or psyllium added herein. The diameter and 1 mm gap).
level of addition was 3% w/w on starch basis. The
starch-hydrocolloid blends were pasted according
Making of jelly candy
to a programmed heating and cooling cycle: Sample
Three recipes for starch-based jelly candy
was first agitated at 960 rpm for 10 sec to impart
preparation are shown in Table 1. Acid-thinned
thorough dispersion, following with holding at 50ºC
starch (Elastigel 1000J) suspension was cooked until
Table 1. Ingredients needed to make jelly candies Ingredients Control Konjac added Psyllium added Glucose syrup (42 DE) (g) 360.0 360.0 360.0 Sugar (g) 300.0 300.0 300.0 Dextrose (g) 110.0 110.0 110.0 Acid-thinned starch (g) 100.0 100.0 100.0 Konjac glucomannan (g) - 3.0 - Psyllium husk (g) - - 3.0 Water (for starch) (g) 550.0 550.0 550.0
Warm water (for citric acid) (ml) 20.0 20.0 20.0 Tri-sodium citrate (g) 4.0 4.0 4.0 Citric acid (g) 4.0 4.0 4.0 Flavoring (g) 1.0 1.0 1.0 Coloring (drop) 1 1 1
International Food Research Journal 18: 213-220
Acid thinned starch 215
Table 2. Pasting properties of acid-thinned starch added with or without konjac glucomannan or psyllium husk. Pasting Properties Control Konjac added Psyllium added Pasting Temperature (oC) 77.85 ± 0.43a 78.82 ± 0.51b 77.27 ± 0.23a Peak Viscosity (RVU) 57.14 ± 0.88a 80.25 ± 3.71b 132.22 ± 3.80c Trough (RVU) 12.45 ± 0.54a 19.08 ± 3.90b 32.05 ± 6.76c Breakdown (RVU) 44.69 ± 0.76a 61.17 ± 1.94b 100.17 ± 4.46c Final Viscosity (RVU) 270.50 ± 9.83a 300.94 ± 12.31b 448.47 ± 37.01c Setback (RVU) 213.36 ± 9.16a 220.70 ± 12.38a 316.25 ± 35.61b
Table 3. Best-fitted parameters of Herschel-Bulkley model for acid-thinned starch suspension with or without added konjac or psyllium Upward curve Downward curve Thixotropic area Sample Flow Flow Yield stress Consistency Yield Consistency ( Pa/s ) behaviour behaviour (Pa) index (Pa.s) stress (Pa) index (Pa.s) index index Control 1.10±1.13a 0.13±0.14a 0.74±0.10b 0.74±0.48a 0.08±0.01a 0.83±0.12a 740.20±180.12a KGM 0.47±0.12b 0.06±0.02b 0.85±0.01a 0.60±0.26a 0.08±0.03a 0.84±0.01a 290.23±55.14b added Psyllium 0.41±0.16b 0.12±0.05a 0.77±0.03b 0.12±0.03b 0.04±0.02b 0.84±0.05a 807.70±177.54a added
Note: Mean ± standard deviation of triplicate samples. Values followed by the same letter in the same column are not significantly different (P>0.05).
Figure 1. Variation of storage modulus (G’) and loss modulus (G”) as a function of frequency
International Food Research Journal 18: 213-220 216
Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
Figure 2. Flow behaviour of acid-thinned starch suspension with or without konjac or psyllium added.
Figure 3. Storage effects on Texture Profile Analysis parameters of different jelly candy prepared.
International Food Research Journal 18: 213-220
Acid thinned starch 217
a clear paste was evident. Where necessary, konjac
effect of konjac or psyllium, or alternatively due to
glucomannan or psyllium powder was pre-mixed
interactions happened between gums and swollen
with a portion of sugar prior adding into the mixture.
starch granules (Rojas and Rosell, 1999) or leached
After two minutes boiling, glucose syrup was added
molecules, i.e. amyloses and amylopectins (Shi and
together with the remaining sugar and dextrose. The
BeMiller, 2002; Funami et al., 2005). On the other
mixture was cooked with continuous stirring until a
hand, the gums may provide additional cushion effect
soluble solid content of 65 ºBrix was reached. Lastly,
to swollen granules to facilitate radial expansion till a
heat was turned off, and citric acid solution, colouring
maximal swelling capacity is reached.
and flavouring agents were added. The suspension
A higher breakdown value was shown in konjac
was then cast into pre-dried corn starch mould
or pysllium added samples. This value was calculated
while it was still hot and free flowing. The cast jelly
as the difference between peak viscosity and trough
samples were then tempered at 65ºC for 24 hours.
value. Therefore, if the difference in trough values
Sample preparation was duplicated and samples were
is marginal, the higher the peak viscosity, the higher
stored in air tight container at 30°C and withdrawn
the breakdown would be recorded. A high breakdown
at 0, 4 and 8 weeks for texture profile analysis. The
was related to a sample structure that is relatively
abovementioned method was modified from National
weaker or less resistant to shearing during heating
Starch & Chemical Company’s technical notes for (Lee et al., 2002). jelly candy making.
On cooling, a relatively higher final viscosity and
setback values were also shown by konjac or psyllium
Texture profile analysis (TPA)
added sample. This can be attributed to thickening
Texture profile analysis (TPA) was performed
effect of each gum in addition to amylose gelation.
directly on jelly candies of specific and consistent
According to the work of Alloncle et al. (1989) and
dimension at ambient temperature with a TA-XT Plus
Yoshimura et al. (1998), it was suggested that an
Texture Analyzer (Stable Micro Systems, Surrey,
increase in the effective concentration of starch in
England) using a cylindrical 75 mm diameter probe
the continuous phase could result in an enhanced
and a 30 kg load cell. Measurements were conducted
interaction between amylose molecules. It is the
at a pre-test speed of 1.0 mm/s, a post-test speed
thermodynamic incompatibility between amylose
of 10.0 mm/s, a test speed of 2.0 mm/s, and 20 g
and konjac, and amylose and psyllium polymers
trigger force. Deformation level was fixed at 75%.
that leads to mutual exclusion of each polymers and
Five sub-samples from each sample preparation were
as a result the local increase in concentration could analyzed.
facilitate molecules rearrangement and association
(Allonce and Doublier, 1991; Funami et al., 2005).
Statistical analysis
Statistical analysis was carried out using
Rheological measurements
statistical software SPSS 14.0 for windows (SPSS,
Frequency sweep. Figure 1 depicts changes
Inc., Chicago, IL, USA). Where necessary, One-
of storage modulus (G’) and loss modulus (G”) of
way ANOVA and Duncan’s test were conducted at a
jelly slurries prepared as a function of frequency.
significant level of P < 0.05.
In general, a plateau-like graph of G’ indicates the
presence of network structures (Kulicke et al., 1996).
Results and Discussion
For all samples, G’ is predominated over G” and G”
increased with increasing frequency, indicating that
Pasting properties
all samples show gel-like behaviour (Steffe, 1996).
Pasting properties of acid-thinned starch
From the mechanical spectra, it is clearly evident that
suspension with or without added konjac or psyllium
psyllium added sample possesses a higher G’, hence
are reported in Table 2. The pasting temperature
it is more elastic or solid-like than konjac added
was slightly increased with konjac addition and
and control samples, which may be attributed to a
no significant difference was evident for psyllium
more cohesive network formed among and between
added sample. Significant differences (P<0.05) were
psyillium and starch molecules. This observation
recorded in peak viscosities, highest values was shown
agrees with those high final viscosity and setback
by psyllium added sample (132.22 RVU), followed by
values reported in previous analysis on pasting
konjac added (80.25 RVU) and control (57.14 RVU). properties.
This shows that a higher viscous load would likely
Stepped flow analysis. As expected, all samples
to be encountered during cooking of the acid thinned
demonstrated a non-Newtonian shear thinning
starch suspension with added konjac or psyllium. Such
rheological behaviour (Figure 2). The hysteresis loop
a phenomenon could be attributed to the thickening
International Food Research Journal 18: 213-220 218
Habilla, C., Sim, S.Y., Nor Aziah. and Cheng, L.H.
shown between the ramp up and ramp down curves
gels resulted and the texture became harder and less
indicates that the sample flow was time-dependent.
deformable upon long-term storage.
The size of the hysteresis loop is related to the
On the other hand, chewiness which is defined
energy needed to destroy the structure responsible
as the energy required masticating a solid food to a
for flow time dependence (González-Tomáz et al.,
state ready for swallowing (Szczesniak, 2002), was
2007). Therefore, the higher the loop area, the more
shown to increase with storage time, however the structured the material.
intensity of increment is reduced substantially upon
Comparing the three samples tested, the flow
addition of konjac or psyllium. This is consistent with
curves of psyllium added sample was significantly
the result of springiness (data not shown), at which
shifted upwards implying that a relatively higher
a less springy gels were demonstrated by konjac or
shear stress is needed to affect a unit flow in psyllium
psyllium added jelly candies. In other words, konjac
added sample as compared to the others. Result
and psyllium addition rendered the acid-thinned
tabulated in Table 3 clearly depicts that konjac starch jelly less chewable.
added sample shows two to three times smaller
As evident in Figure 3, the attributes of
thixotropy value. This suggests that konjac may have
adhesiveness was not shown in all fresh samples, but
significantly weakened the network structure of starch
it appeared after storage. It increased significantly
molecules, and rendered the blend easier to deform
higher in the control samples than gums added
and recover upon removal of shearing load. This in
ones. This indicates that konjac or psyllium helps to
turn explains why lower yield stress and consistency
enhance the water holding capacity of acid-thinned
values together with a higher flow behaviour index starch jelly candy.
were evident in sample added with konjac. From the
lower yield stress values, it can be anticipated that Conclusions
jelly slurry supplemented with konjac or psyllium is
easier to be pumped from the cooker for deposition.
This study showed that konjac and psyllium at
relatively small amount can modify the physical
Texture profile analysis (TPA)
performance of acid-thinned starch in jelly candy The changes of hardness, cohesiveness,
production. From the results obtained, though konjac
chewiness, and adhesiveness of jelly candies prepared
or psyllium was found to produce a higher viscous
are illustrated in Figure 3. The hardness of fresh jelly
starch suspension during cooking, the jelly slurry
candy samples tested were found to decrease with
prepared can be pumped easily during deposition
addition of konjac or psyllium , but it progressively
with a relatively lower yield stress value, when
increased as the samples were stored for 8 weeks at
compared with the control sample. Apart from this,
30°C. The reverse trend was observed for samples
gums addition enhanced the water holding capacity
cohesiveness. According to Szczesniak (2002),
of acid-thinned starch jelly candy. Overall, the jelly
hardness and cohesiveness were defined as the force
candy quality characteristics supplemented with
required attaining a given deformation and the extent
konjac or psyllium were found to be acceptable with
to which a material can be deformed before it ruptures, reduced stickiness.
respectively. Hence, these observations suggest that
konjac and psyllium are effective in delaying short- Acknowledgements
term retrogradation. Our result is in line with the
work of Funami et al. (2005), which reported that
This work was supported by a short-term grant
when galactomannan was added to wheat starch, the
(Grant No.:304/PTEKIND/638019) and USM
dynamic mechanical loss tangent of the blend was
Fellowship scheme funded by Universiti Sains
found to increase during short-term retrogradation, Malaysia.
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