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Extraction of Starch from Taro (Colocasia esculenta) and Evaluating it and

further using Taro Starch as Disintegrating Agent in Tablet Formulation with
Over All Evaluation.

Article · March 2013

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 RESEARCH ARTICLE

Extraction of Starch from Taro (Colocasia esculenta) and

Evaluating it and further using Taro Starch as Disintegrating
Agent in Tablet Formulation with Over All Evaluation
Azhar Ahmed1*, Farukh Khan1
Abstract: Taro has been reported to have 70–80% starch with small granules, Because of the small sizes of its starch granules,
taro is highly digestible. On the basis of current evaluation of properties of starch it has been found that taro starch can be
utilized as a better disintegrant as compared to the other traditional starches, Starches are used since a long time as exipients in
pharmaceutical preparations. Mainly maize starch, potato starch and wheat starch are used and monographed in several
pharmacopoeias. The classical functionalities of native starches in the past are fillers and disintegrants in tablets and fillers in
dermatological powders. Also modified (pregelatinized) starches have been used as filler-binders in tablet technology. After this
research activity Taro starch can be introduced in the pharmaceutical field and further more research can be done over this
starch to make it highlighted in the arena of pharmaceutical research. In addition to food use, taro has found some industrial
applications. The very small size of taro starch granules makes them ideal in cosmetic formulations like face powder and in
dusting preparations which use aerosol dispensing systems. In spite of the above uses, the large-scale extraction and utilization
of this starch is not practised anywhere. So after this research activity the taro starch can be brought to the minds of researchers
and it can gain attention in the field of pharmaceutical research.

INTRODUCTION Taro (Colocasia esculenta) tuber has not been reported

Starch is a carbohydrate consisting of a large number of extensively so, The purpose of this study is to extract the
glucose units joined together by glycosidic bonds. This starch from Taro (Colocasia esculenta) and evaluating it,
polysaccharide is produced by all green plants as an energy and further using taro starch as disintegrating agent in
store. It is the most common carbohydrate in the human tablet formulation with over all evaluation. In short from
diet and is contained in large amounts in such staple foods this research activity it can be said that taro starch can be
as potatoes, wheat, maize (corn), rice, and cassava. It is introduced to the modern arena of research, and hence it
either used as extracted from the plant and is called “native can be proved better and efficient than other natural
starch”, or it undergoes one or more modifications to reach starches mainly as disintegrant and can be further modified
specific properties and is called “modified starch”. Pure with various researches made over it.
starch is a white, tasteless and odourless powder that is
insoluble in cold water or alcohol. It consists of two types of Taro
molecules: the linear and helical amylose and the branched 1. Scientific Classification
amylopectin. Depending on the plant, starch generally Botanical name: Colocasia esculenta
contains 20 to 25% amylose and 75 to 80% amylopectin. Kingdom: Plantae
It is obvious that starch has moved from its traditional Order: Alismatales
role as food to being an indispensable medicine. The wide Family: Araceae
use of starch in the medicine is based on its adhesive, Sub Family: Aroideae
thickening, gelling, swelling and film-forming properties as Tribe: Colocasiodeae
well as its ready availability, low cost and controlled Genus: colocasia
quality. From the foregoing, to think that starch is still Species: C. esculenta
ordinary inert excipients is to be oblivious of the influence Common names: Taro, Kalo, Eddy root, wild taro, Arvi,
this important biopolymer plays in therapeutic outcome of Talas.
bioactive moieties. Starch has proven to be the formulator’s
“friend” in that, it can be utilized in the preparation of 2. Description [1]
various drug delivery systems with the potential to achieve A long stalked herbaceous plant with huge leaves, growing
the formulator’s desire for target or protected delivery of to the height of 30 to 150 cms. Rootstock is tuberous up to
bioactive agents. Maize starch, extra white maize starch, 10 cm in diameter. The leaves in groups of two or three are
wheat starch and potato starch are long-known and reliable long petiolaed, ovate, 20 to 50 cm long, glaucous, with the
excipients used as insoluble diluents that act as fillers in the insertion of the petiole, with broad and rounded basal
formulation of tablets and capsules, and as powders for lobes. Petioles are green or purplish, 0.2 to 1 m long. Spathe
sachets, all while retaining a disintegration function. is variable in length, about 20 cm long. Spadix is cylindric,
Generally starch is isolated from potatoes, wheat, maize half as long as the spathe, green below and yellowish
(corn), rice, and cassava etc. But Starch extraction from above.

3. Constituents [1]
1NRI Institute of Pharmacy, Sajjan Singh Nagar, Raisen Road, Bhopal – The tuber is chemically composed of vitamin C, thiamine,
462021, M.P., India.
E-mail: azharamd@hotmail.com riboflavin, niacin, oxalic acid, calcium oxalate, pelargodin 3
*Corresponding author glucoside, cyaniding 3 rhamnoside, cyaniding 3 glucoside,

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 RESEARCH ARTICLE

hydroxyl cinnamoyl amides, benzaldehyde 3 4 di O beta professor) and authentification of plant is

glucoside, beta carotene, colocasia sterols, fructose, glucose 257/Bot/saifia/12. Tubers were washed and air dried.
and sucrose. It also has high starch content. Dried tubers part of Colocasia esculenta were crushed to
The leaves are rich in calcium phosphate and iron. It fine powder using grinder at N.R.I. Institute of Pharmacy,
contains about 2.26 ppm of iodine. Bhopal and stored in an air tight container for further
Among the constituents found, there is a bitter studies.
substance called acorine which appears to be a
nitrogenated glucoside and an aromatic essential oil. Extraction of Starch from Tubers
Taro tubers was collected and cleaned properly washed.
4. Uses [1] After washing outer covering layer was peeled. The tuber
a. Medicinal Use was than sliced and kept for drying at room temperature.
Taro was used by Hawaiians to treat illness ranging from After drying, the dried sliced tuber pieces were crushed in
constipation to tuberculosis. It is used as a laxative in cases mixer grinder to form the powder. This powder is further
of haemorrhoids. The raw juice mixed with sugar was used for extraction of starch. Starch was extracted by three
taken orally to reduce fever. The leaves of the plant are rich methods which are as follows;
in vitamins A, B and C and were used to treat asthma. Taro
is good for people allergic to milk or cereals and can be 1. Extraction by Simple Process
consumed by children who are sensitive to milk. It acts as a Taro powder (50 gm) was taken and dispersed in 100 ml of
probiotic because it contains the predominant lactic acid water; the mixture was homogenized for about 30 mins, by
bacteria. Studies have been reported its possible beneficial using homogenizer. Resulting solution was kept overnight.
role in the treatement of diarrhoea, gastroenteritis, On next day the solid and liquid layer gets separated, solid
irritable bowel syndrome and inflammatory bowel disease, material gets deposited at the bottom of the glass beaker
cancer, depressed immune function and inadequate lactase while the liquid floats at upper surface. The liquid layer is
digestion. In Philippines, taro leaves and corms were boiled decanted and remaining sediment is washed with excess of
and eaten by women experiencing a difficult childbirth. water. After washing the water is decanted and the starch
Some tribes use taro as an antidote to the stings of wasps powder is obtained by filtration through whattman filter
and other biting insects, heated tubers were applied to paper, powder is kept for drying. The obtained powder
painful parts in rheumatism. Honey mixed with tuber ash after drying is starch powder.
was also used as a cure for apthae in the mouth.
2. Wet Milling Process [2]
b. Industrial Use Taro powder (50 gm) was steeped in a sodium
Although it was not common in practice, the petioles were metabisulphite solution (150 ml, 0.45% W/V) overnight in
sometimes used to make dots of semicircle designs on a refrigerator. Now the slurry is was milled using a
cloth. In fact, certain varieties were used as a source of red commercial food blender for 5 min. The blended slurry was
kapa dye. Taro starch is used in the manufacture of mixed with 450 ml NaCl solution (0.1 M) and 50 ml
biodegradable plastics. Toulene. The mixture was stirred for 1hr and then allowed
to stand until the starch granules settled at the bottom. The
c. Food Source protein in toluene and NaCl solution layers was siphoned
The starch contained in the large corms of taro is highly off and discarded, and this was repeated until all of the
digestible, therefore making it a good source for proteins were removed as indicted by a clear toluene layer
carbohydrate and to a lesser degree a source of potassium after the starch granules settled at the bottom. The starch
and protein. layer was then washed with water several times and
subsequently with absolute ethanol. The wet milled starch
MATERIALS AND METHODS was then recovered by filtration through Whatman filter
Experimental Work paper, rinsed with ethanol and air dried.
Experimental work of this Research activity consists of the
following sections: 3. Centrifugation Process [3]
1. Collection of tuber Taro powder (20 gm) steeped in 50 ml of 1% sodium
2. Extraction of starch from tubers metabisulphite solution at 45qC for 24, 48 or 72 hours. The
3. Preliminary testing of starch liquid phase is separated. The separated slurry paste was
4. Formulation of tablet using extracted starch as placed in a 50 ml centrifuge tube with 10 ml of distilled
disintegrating agent water and homogenized using a homogenizer for 30 sec.
5. Overall evaluation of starch and its properties The homogenized slurry was filtered by using a fine nylon
filter under vacuum with several washes for a total wash
Collection of Tubers and Identification water volume of 500 ml. Coarse and fine fibers and a part of
Tubers were collected locally from Bhopal. Herbarium was protein were removed during filtration. The starch protein
prepared and submitted at botany department of Saifia mixture from the filtrate was further separated by either
College, Bhopal for authentication. The botanical identity of centrifugation or sedimentation. (In this case
the plant was confirmed by Dr. Zeaul Hasan. (Assistant centrifugation performed).

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 RESEARCH ARTICLE

Figure 1: Globules of starch extracted by centrifugation Figure 2: Globules of starch extracted

Figure 3: Globules of starch extracted Figure 4: Globules of corn starch

Table 1: Observations of Physical Tests

Moisture Melting Point

Types of Starch Bulk Tapped Angle of
Content Particle Size (Thieles Tube
Extract Density Density Repose
(IR Balance) Apparatus )
0.33 0.363 2 to 20
Normal Method 1.7% L.O.D 29.66q 266 ±2qC
gm/cm3 gm/cm3 micrometer
0.32 0.344 2 to 20
Wet milling Method 1.6% L.O.D 25.74q 268±2qC
gm/cm3 gm/cm3 micrometer
Centrifugation 0.35 0.400 2 to 20
1.6% L.O.D 26.22q 268±2qC
Method gm/cm3 gm/cm3 micrometer

Table 2: Observations of Chemical Tests

Benedict Test Molish Test Legal Test Reducing Sugar

Types of Starch Extract Protein Test
(Sugar) (Carbohydrate) (Glycoside) Test
Normal Method positive positive positive Negative Negative
Wet Milling Method positive positive positive Negative Negative
Centrifugation Method positive positive positive Negative Negative

Centrifugation: The starch slurry was centrifuged for 30 Formulation of Tablet Using Extracted Starch as
mins. The supernatant was decanted, the protein layer was Disintegrating Agent
scraped off and more water added to the partly cleaned Formulation of placebo tablets is formulated by using
starch, with centrifugation and decanting repeated three standard corn starch and extracted taro starch as
times. The resulting sediment was air dried. disintegrating agents with other exipients. Later on tablet
was prepared by direct compression, dry granulation and
Preliminary Testing of Extracted Starch wet granulation methods.
Preliminary testing of starch is done by evaluation of
various physical and chemical parameters. The results of 1. Formula [4]
preliminary study are shown in Table 1 and Table 2. Ingredient Quantity
While particles size is shown in Figures 1, 2, 3 and 4 1. Microcrystalline cellulose (binder) 38.4 gm
respectively. 2. Lactose (filler) 38.4 gm

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 RESEARCH ARTICLE

Table 3: Evaluation of Tablets Made From Taro Starch which is Extracted by Simple Process with Water (Tablet A)

Hardness Friability Disintegration Time

Granulation Type Wt. Variation (%)
(Kg/cm2) (%) (mins)
Direct Compression 8 1.2 3 7.20
Dry Granulation 8.5 1.2 2.1 6.44
Wet Granulation 10 1.1 1.8 7.30

Table 4: Evaluation of Tablets Made from Taro Starch which is Extracted by Centrifugation Process (Tablet B)

Hardness Friability Wt. Variation Disintegration Time

Granulation Type
(kg/cm2) (%) (%) (mins)
Direct Compression 10 1 2.3 6.12
Dry Granulation 9.5 1.2 3.4 6.40
Wet Granulation 9 1 2.5 5.22

Table 5: Evaluation of Tablets made from Taro Starch which is Extracted by Wet Milling Process (Tablet C)

Hardness Friability Wt. Variation Disintegration Time

Granulation Type
(kg/cm2) (%) (%) (mins)
Direct Compression 10 1.1 3.1 5.30
Dry Granulation 11 1 3 4.15
Wet Granulation 11 0.8 2.4 3.15

Table 6: Evaluation of Tablets, Taro Starch Tablet Compared with Reference Tablets

Selected Tablet of
Potato starch
S. No. Property Taro Starch Corn Starch Tablet
Tablet
(Tablet C, Wet Granuled)
1. Hardness (Kg/cm2) 11 11 12
2. Weight variation % 2 1.5 2
3. Friability % 0.8 1.2 1
4. Disintegration Time (mins) 3.15 5.20 4.55

3. Starch (disintegrant) 2.4 gm 4. Preparation of Placebo Tablets by Dry Granulation

4. Magnesium stearate (lubricant) 800 mg Method
Milling of different components is done, proper quantity
2. Preparation of Placebo Tablets by Direct of ingredients are milled. Mixing of milled powders is
Compression Method done as a followed by sieving with sieve No. 22, now
Compressed tablets were prepared by direct compression after mixing compression is done into large hard tablets
method employing starch as disintegrating agent. All the to make slug. After obtaining slugs, Screening of slugs is
materials required as per the formulae were blended in a done followed by crushing them and again screening of
closed polyethylene bag. The blends were compressed into the crushed slugs by using a sieve of no. 40. The
tablets on a tablet punching machine to a hardness of 10 screened powder is the mixed with screened lubricant
kg/cm2 using round and flat punches. In this case, 30 and disintegrating agent powder and finally the tablet is
tablets were compressed. compressed or punched by using rotary tablet punching
machine
3. Preparation of Placebo Tablets by Wet Granulation
Method Evaluation of Tablets
Accurately weighed quantities of each ingredient were 1. Hardness Test
mixed in a mortar and an appropriate quantity of the Five tablets were selected at random from each batch to
microcrystalline cellulose (with distilled water) was added perform this test. Pfizer hardness tester (Elite, Mumbai,
as a granulating agent and mixed for 20 min in a mortar. India) was used to measure the hardness. Tablet was
The damp mass was sieved with sieve no. 22 and dried at placed between spindle and anvil of the tester and the
50qC in an oven for 6 hrs. The dried granular mass was calibrated scale adjusted to zero, then diametric
passed through sieve no. 40 to obtain uniform sized compression force was applied on the tablet and the
granules. The batch of the granules and specified amount of position on the calibrated scale at which the tablet broke
the disintegrant i.e. Taro starch were then mixed with was recorded in kg units. A mean hardness was calculated
calculated equal quantity of magnesium stearate and then for each batch.
compressed into tablets under constant pressure with a
rotary tablet machine. 2. Weight Uniformity Test

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 RESEARCH ARTICLE

Twenty tablets were selected randomly from each batch CONCLUSION

and weighed. The mean weights were calculated for each The present study reveals that results obtained showed
batch. some differences on the properties of the starch obtained
from Taro and other traditional starch sources like potato
3. Friability Test and corn. Taro has been reported to have 70–80% starch
Ten tablets were selected randomly, dusted, weighed with small granules, Because of the small sizes of its starch
together and then placed in the friabilator. The machine granules, taro is highly digestible. On the basis of current
was operated for 100 rotations at 25 rpm and then evaluation of properties of starch it has been found that
stopped. The tablets were dusted and again reweighed. The taro starch can be utilized as a better disintegrant as
percentage losses were calculated. compared to the other traditional starches, Starches are
used since a long time as exipients in pharmaceutical
Friability f=I-F*100/I preparations. Mainly maize starch, potato starch and wheat
Where, I=initial weight of tablets, F=weight after friability. starch are used and monographed in several
Normal limits less than 1%. pharmacopoeias. The classical functionalities of native
starches in the past are fillers and disintegrants in tablets
4. Disintegration Time [5] and fillers in dermatological powders. Also modified
According to the method specified in the USP/NF (1980), (pregelatinized) starches have been used as filler-binders
100 ml of 0.1 N HCl was used as disintegration medium at in tablet technology. After this current research activity
temperature 37±2°C throughout the experiment. Taro starch can be introduced in the pharmaceutical field
Randomly selected five tablets from each batch were and further more research can be done over this starch to
placed one in each of the cylindrical tubes of the basket make it highlighted in the arena of pharmaceutical
but no disc was used. The time taken for each tablet to research. In addition to food use, taro has found some
break up into small particles and pass out through the industrial applications. The very small size of taro starch
mesh was recorded. Mean disintegration time was granules makes them ideal in cosmetic formulations like
calculated for each batch. face powder and in dusting preparations which use aerosol
The results of evaluation are shown in Table 3, Table 4 dispensing systems. In spite of the above uses, the large-
and Table 5. scale extraction and utilization of this starch is not
NOTE 1: During punching of the tablets it was found practised anywhere. So after this research activity the taro
that the granules which was prepared by wet granulation starch can be brought to the minds of researchers and it
process are getting easily filled in the dyes and the tablets can gain attention in the field of pharmaceutical research.
which are produced from wet milled taro starch (Tablet C)
are of good property and uniform as compared to the REFERENCES AND NOTES
tablets which are made from granules of direct 1. Martin, Cyanophoic Glycosides, 3G Pharmacy. Acs publication,
compression and dry granulation process. So for the 2000.
further process the wet granulated tablet C are used. 2. Z A Syahariza, Enpeng Li, Jovin Hasjim. Extraction and
NOTE 2: Potato and corn starch tablets are formulated dissolution of starch from rice and sorghum grains for
accurate structural analysis. Carbohydrate Polymers, 82:14–
as reference tablets, formula is used same as of taro starch
20, 2010.
tablets just the difference is that taro starch is replaced 3. Y Ji, K Seetbaraman and P J White. Optimization of small scale
with Potato and corn starch, And tablets was made by wet corn starch extraction method for use in the library. Journal of
granulation process. Results of taro starch tablet Cereal chemistry, 81(1):55-58, 2004.
compared with potato and corn starch tablet are shown in 4. Bruno C Hancock, Joshua T Colvin, Matthew P Mullarney,
Table 6. Andrey V Zinchuk. The Relative Densities of Pharmaceutical
Powders, Blends, Dry Granulations, and Immediate-Release
RESULTS Tablets. Journal of pharmaceutical technology, 64-80, 2003.
Starch has been extracted from Taro successfully by three 5. Elevina Perez, Forrest S Schultz, Emperatrı´z Pacheco de
Delahaye. Characterization of some properties of starches
methods of extraction and it has been found that the starch
isolated from Xanthosoma sagittifolium (tannia).
which is extracted by wet milling method shows better Carbohydrate polymers, 60, 139-145, 2005.
property as compared to other two methods. Tablets which
are prepared from wet milled extracted starch by wet
granulation process shows better disintegration. And after Cite this article as: Azhar Ahmed, Farukh Khan.
comparison with standard reference tablets i.e. potato and Extraction of Starch from Taro (Colocasia esculenta) and
Evaluating it and further using Taro Starch as
corn starch placebo tablets, the taro starch tablet shows
Disintegrating Agent in Tablet Formulation with Over All
better disintegration as compared to the reference tablets Evaluation. Inventi Rapid: Novel Excipients, 2013(2):1-5,
due to this it can be proved that the taro starch is a better 2013.
disintegrant as compared to the other natural starches.

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