International Journal of Research and Reviews in Pharmacy

RESEARCH ARTICLE Uchendu, Nene O et al, IJRRPAS, 2013, June, 3(3)370-386, ISSN 2249-1236

370 Available on www.ijrrpas.com

INTRODUCTION

CHARACTERIZATION OF DIFFERENT VARIETIES OF CASSAVA STARCH FOR INDUSTRIAL

UTILIZATION.

ABSTRACT

Physical and biochemical analyses were carried out on different varieties of cassava (Manihot esculenta Crantz) starch. The

result obtained from the pH measurements gave acidic pH values within the range of 4.8 to 5.5. However, each of the three

different varieties (8082, 8083 and NWIBIBI) gave pH values of 3.0. The gelatinization temperature was within the range of

68°C to 71°C. The acid binding factor shows that NWIBIBI had the highest acid factor of 1.45 while variety 209 had the lowest

binding capacity of 0.6. NWIBIBI also had the highest percentage ash content of 69.0 while the variety 218 had the lowest

(value of) 25.0. Clarity of starch paste showed that all varieties were translucent under hot conditions and opaque in cold

conditions. There is an increase in swelling power with increase in temperature. The temperatures used were 50°C, 60°C, 80°C

and 90°C. Finally, the varieties which were subjected to methylene blue differential dyeing, gave light blue colours. The

relevance of these is that in food industries, pH tests can be used to detect the presence of moulds or other impurities, the

clarity of the starch paste is exploited in the production of different snacks in industry. This is also applied in paper,

pharmaceutical and paste industries. In most industrial processes, starch with low gelatinization temperature, acid factor and

ash content is preferred.

Keywords: Starch, Cassava, Gelatinization temperature, Ash contents and Manihot esculenta Crantz.

International Journal of Research and Reviews in Pharmacy and Applied science

www.ijrrpas.com

Uchendu, Nene O*., Eze,

Sabinus,O.O.,

Ugwu,Okechukwu P.C.,

Enechi O.C. and Udeh,

Sylvester M.C.

Department of Biochemistry,

University of Nigeria, Nsukka.



INTRODUCTION

Cassava is a tropical woody shrub of the family euphorbiacceae, possessing tall, thin, straight stems and when fully grown, attains an average height of

1-2 metres although some cultivars may reach a height of 4 meters. The stem is often marked along its entire length by numerous leaf scars indicating

the position from where its palmate leaves of five or six leaf lets have dropped off.

Depending on the variety and age of the plant, the fibrous roots may be up to 100 centimeters long. Some of these fibrous roots undergo the process of

tuberization (swelling due to the cambium tissue) leading to increase in the diameters of the roots (Nweke, 1996).

Although the leaves of the plant have been found to be rich in protein, vitamin and other nutrients, the tuberous root (root tuber) is the major source of

cassava food, usually starch (and farms largely) depend on the level of production and the quality of starch in the roots (Nweke et al., 2002).

Chemically, fresh cassava tuber consists primarily of water 62-65%, carbohydrate 32-35% which is concentrated in two starch fractions of (amylose

/and amylopectin) of the tuber, protein 0.1-2.6%, fibre 0.8-1.3%, ash 0.3-1.1% and fat 0.2-0.5% (Gerald et al., 2001).

Classification of Cassava

Cassava is one of the commonest foods in the world especially in South America and the West African sub-region. The scientific classification of cassava

is as follows:

Kingdom Plantae-plants

Sub-kingdom Tracheobionta-vascular plants

Super division Spermatophyta-seed plants

Division Magnoliophyta-flowering plants

Class Magnoliopsida-dicotyledons

Sub class Rosidae

Order Euphorbiales

Family Euphorbiacae-spurge family

Sub family crotonoidaea

Tribe Manihoteae



Genus Manihot

Species Manihot esculenta Crantz

Cassava (Manihot spp.) also called tapioca, yucca, manioc, and mandioca in various parts of the world, has its origin in Brazil where it is the major staple

food of the people. It was originally native of the Tupinamba or the Amazon Indians of Eastern Brazil from where it was dispersed to other parts of the

world by Portuguese explorers (IITA, 1990).

Cassava is the fourth major food crop that is extensively cultivated in the tropics (FAO, 1989), with a global production of about 160 million tons. Most

of this is grown in three regions: West Africa and the adjoining Congo basin, Tropical South America and Southeast Asia.

Cassava is the most widely grown staple food in Nigeria especially in the southern part of Nigeria. Propagation of cassava is by planting segments of the

stem. The stem is cut about 8-14 inches (20.3-35.6cm) in length, being sure to include at least one mode. Each “stick” (segment) is buried 3-6 inches

(7.5-15cm) deep; segments can be buried horizontally or vertically inside the ground.

Cassava is well adapted to poor soils with marginal nutritional status and pH of 4 to 9 (Tewe, 2004). It is good candidate for starch production because

it has a high photosynthetic rate; an ability to grow on poor soils and it is protected from many pests and herbivores due to the presence of cyanogens

(Ihemere et al., 2006). It is a widely adapted crop which can grow at altitudes of 0.180cm; fertile to marginal or very poor soils, and rainfall of <500-

2000mm/year (Mkumbira et al., 1997).

There are many varieties of cassava under cultivation in Nigeria. The improved varieties yield between 25-40 tons per hectare, they are equally

resistant to pests and diseases and have acceptable culinary and industrial qualities (Breckelbaum et al., 1978, NRCRI, 1982-1997, IITA, 1976-1996). In

comparison, local varieties yield between 5-10t/ha and are very susceptible to pests and diseases (IITA, 1976-1996).

Cassava varieties are classified according to the levels of cyanogenic glycosides (hydrogen cyanides, HCN) in the roots and leaves (IITA, 1996). Cassava

with high HCN level – 100mg per kilogramme fresh weight or more e.g. TMS 30395; cassava with intermediate levels of HCN ranging 50 and 100mg per

kilogramme fresh weight e.g. TMS 30572, TMS 30555; cassava with low HCN level – less than 50mg kilogramme fresh weight e.g. TMS 4(2) 1425, TMS

30001.

For more than 500 million people in Africa, Asia and South Africa, cassava provides income, employment and food security (Padmaja, 1995). It counts as

one of the leading crops with respect to the energy produced per hectare and year. The world production has steadily increased in the last 35 years and

now the worldwide cassava production has doubled (Plucknett et al., 2001). In 2002, about 186 million tons of cassava was produced. More than half of

that amount was produced in Africa (55%), the rest in Asia (28%) and South America (17%) (FAO Stat., 2005).



MATERIALS AND METHODS

PLANT MATERIALS

The different varieties of cassava starch (Manihot esculenta Crantz)] were procured from International Institute of Tropical Agriculture, IITA Ibadan.

Instruments/Equipment Used

Beakers Pyrex, Conical flasks Pyrex, Burette Pyrex, Measuring cylinder Pyrex, Water bath Giant Instrument Limited, Centrifuge tubes, Spatula, Test

tubes Pyrex, Weighing balance LARK® , Funnel, Buchner funnel Royal Worcestea, Thermometer, Ashing dish, Oven, Desicators Pyrex, Hot plate

Pyrex, Filter paper Whatman, Petry dish, pH meter (digital) B. Bran, Reagent bottles Pyrex, Magnetic stirrer,Vacuum pump Sargent-Welch, Dropper and

Retort stand.

Chemical/Reagents

Ethanol (90%) BDH, Hydrochloric acid (HCl) BDH, Sodium Hydroxide (NaOH) BDH, Phenolphthalein BDH, Silver Nitrate BDH and Methylene

blue .

METHODS

Preparation of Reagents

Prepration of Phenolphthalein

0.1g of phenolphthalein was dissolved in 90% ethanol and made up to 100mls in a measuring cylinder.

Preparation of 0.1% Methylene Blue

0.1g of methylene blue was weighed out and dissolved in 10cm3 of water and made up to 100cm3 of distilled water.

Preparation of 0.1N HCl

The preparation was done following the procedure stated below:

The normality of industrially prepared concentrated HCl is got as follows:

Normality = ..100

.1000%

wtMolX

gravitySpXXAssay



.12

46.36100

19.1100038

N

X

XX

Therefore, to prepare 1 litre of 0.1 NHCl,

N1V1 = N2V2

where

N1 = Normality of the concentrated HCl or the stock HCl solution

V1 = Volume required from the stock solution

N2 = Normality to be prepared

V2 = Volume to be prepared

From above,

12 X V1 = 0.1 X 1000

V1 = 12

10001.0 X

= 8.33

8.33 mls of the stock (concentrated) HCl solution was pippetted and dissolved in 1000cm3 of distilled water.

Preparation of 0.2N HCl

Following the same procedure as above

N1V1 = N2V2

12 X V1 = 0.2 X 1000



V1 = 12

10002.0 X

= 16.667

16.67 mls of the stock (concentrated) HCl solution was pippeted and dissolved in 100ml of distilled water.

Preparation of 0.1N NaOH

40g of NaOH was dissolved in 100mls of distilled water = IN

Therefore 4g of NaOH = 0.1N

4g of NaOH was weighed out and dissolved in 10cm3 of water and then made up to 1000cm3 of distilled water.

Determination of pH

Three grams of each variety was weighed and dissolved in 40mls of distilled water. The solution was agitated vigorously for 15 minutes and allowed to

settle for 55 mins. The water phase was decanted and used to determine the pH. The pH was measured using a pH meter.

Determination of Gelatinization Temperature

Three grams of each variety was weighed and dissolved in 40mls of distilled water and agitated. This solution was poured out from the test tube into a

small beaker (50mls). The beaker was placed inside a bigger beaker (250mls) filled with water. Magnetic stirrer was used to stir the starch solution.

This was placed on a magnetic heater and was heated until the starch gelatinized. The temperature at which each variety turned into a gel was noted

and recorded

Determination of Acid Factor

Four grams of starch was weighed into a 250ml beaker and about 10mls of distilled water was added and the mixture was stirred. The pH of the

solution known as slurry was noted. The starch solution in the 250ml beaker was titrated with 0.1N HCl from a burette till a pH of 3.0 was reached. The

amount of acid consumed in the titration of each variety was noted and recorded. This was used to calculate the acid factor.



Determination of Acidity

Starch milk was prepared by taking equal volumes of starch and water (5 grams and 5mls respectively). The starch milk was poured into 250ml beaker

and about two drops of phenolphthalein indicator was added. This solution was titrated with 0.1N NaOH to obtain a faint persistent pink, alternatively

to a pH of 8.3. The volume in mls of the 0.1N NaOH consumed for each variety was noted and recorded.

Determination of Ash in Starch at 900°C

The ashing dish used was carefully cleaned and heated for about an hour in a furnace at 900°C. The dish was brought out and cooled in a dessicator at

room temperature and weighed on a balance to the nearest 0.1mg. Five grams of starch sample was distributed in a uniform layer in the dish. After this,

the dish was weighed again to the nearest 1mg. The starch sample was incinerated on a hot plate until completely carbonized. The incineration was

completed in a hot plat at 900°C until residual carbon disappeared. The ash was cooled in a desiccator at room temperature; weighed immediately after

removal to the nearest 0.1mg.

Determination of Paste Clarity

Five grams of the different starch varieties were suspended in 5mls deionized water and gelatinized. The paste was poured into a clean dry petri dish

and labeled. The clarity of the paste was observed immediately after cooking (hot condition) and after cooling at room temperature (cold condition).

Peltry dishes containing starch paste were photographed against a black and white background to help visual observation of the paste transparence of

opacity.

Determination of Swelling Power of Starch

Five grams of the different varieties were weighed out and 20mls of deionized water was added. This suspension of starch in deionized water was

placed in a water bath under agitation at 50°C. After 30 minutes, the samples were centrifuged (3,4000 rpm/15 minutes) after which the supernatant

was decanted. The pellets containing the swollen starch granules were weighed. The ratio between the final mass and the initial dry matter was

considered to be the swelling power. The same procedure was repeated for the different varieties at the selected temperatures (60°C, 80°C and 90°C).

Determination of differential Dyeing Capacity of Starch

One gram of each of the varieties was suspended in 25ml of 0.1% methylene blue under agitation for 30 minutes. The suspension was washed with

deionized water and filtered. The samples were dried in air oven at 50°C.



RESULTS

PH VALUES

The results obtained from the pH measurement of different cassava starch varieties are shown below:

Variety pH Value

104 5.0

109 4.8

114 4.7

119 5.0

121 4.9

202 5.5

208 4.9

209 5.5

217 4.9

218 5.1

8082 3.0

8083 3.0

NWIBIBI 3.0

Table 1: pH values of different starch varieties

The results on Table 1. above show that most of the starch varieties had pH values between the range of 4.8 to 5.2 that is acidic pH. However, three

varieties (8082, 8083, and NWIBIBI) gave very high acidic pH values of 3.0 each. The low pH could be due to differences in processing methods.



GELATINIZATION TEMPERATURE

Variety Temperature (°C)

104 69

109 69

114 68

119 70

121 69

202 68

208 70

209 69

217 68

218 70

8082 71

8083 71

NWIBIBI 71

Table 2: Gelatinization Temperature of different cassava starch varieties

The results in Table 2 above show that the gelatinization temperatures of the starch varieties were within 68°C to 71°C.



ACID FACTOR

Variety N V(cm3) Acid factor 10NV

104 0.1 1.10 1.10

109 0.1 0.80 0.80

114 0.1 0.70 0.70

119 0.1 0.80 0.80

121 0.1 0.70 0.70

202 0.1 1.00 1.00

208 0.1 0.70 0.70

209 0.1 0.60 0.60

217 0.1 0.80 0.80

218 0.1 0.80 0.80

8082 0.1 1.11 1.11

8083 0.1 1.30 1.30

NWIBIBI 0.1 1.45 1.45

Table 3: Values of acid factor of different cassava starch varieties are shown below.

The result on Table 3 above shows that acid factor of most starch varieties were between 0.6 to 0.8, other have acid factor of 1.10 to 1.45. The variety

with the highest factor NWIBIBI, this might be as a result of the difference in processing.



ACIDITY

Variety N V(cm3) Acidity = NV/50

104 0.1 0.20 0.0004

109 0.1 0.20 0.0004

114 0.1 0.10 0.0002

119 0.1 0.20 0.0004

121 0.1 0.20 0.0004

202 0.1 0.10 0.0003

208 0.1 0.20 0.0004

209 0.1 0.20 0.0004

217 0.1 0.15 0.0003

218 0.1 0.15 0.0003

8082 0.1 0.20 0.0004

8083 0.1 0.20 0.0004

NWIBIBI 0.1 0.20 0.0004

Table 4: Result for the determination of acidity of different starch varieties

From the result on Table 4, the variety 114 has the lowest value of acidity which is 0.0002 the other varieties have values of 0.0003 and 0.0004.



ASH CONTENTS OF STARCH AT 900°C

Variety W0(g) W1(g) W2(g) % Ash Content

104 35.00 39.95 36.70 34.30

109 33.35 38.35 34.95 32.00

114 24.45 29.45 26.00 55.00

119 32.50 37.50 34.30 36.00

121 34.90 39.90 36.20 26.00

202 32.40 37.40 34.00 32.00

208 25.00 30.00 27.00 40.00

209 32.15 37.15 33.90 35.00

217 24.10 29.05 25.85 35.30

218 25.20 30.20 26.45 25.00

8082 34.00 39.00 36.10 42.00

8083 32.50 37.50 35.20 54.00

NWIBIBI 34.30 39.30 37.7 69.00

Table 5: Percentage of ash content cassava starch varieties at 900°C

The results in Table 5 above show that ash content obtained for most varieties were between 25% to 42% while varieties like 8083 and NWIBIBI gave

ash content values of 54% and 69% respectively. This increase in ash content may be as a result of high inorganic ions.



CLARITY OF STARCH PASTE

The paste clarity of starch varieties observed under hot condition and under cold condition.

Variety Paste clarity

(Hot condition)

Paste clarity

(cold condition)

104 Translucent Opaque












NWIBIBI Translucent Opaque

Table 6: Results of clarity of starch paste.

From the results in Table 6 above, all the starch varieties were translucent under hot conditions whereas they were all opaque under cold conditions.

These were viewed under black and white backgrounds in the photograph.



SWELLING POWER OF STARCH

The swelling power of starch was obtained by dividing the final mass with the initial dry weight.

Variety 50°C

W(g)

S.P

60°C

W(g)

S.P

80°C

W(g)

S.P

90°C

W(g)

S.P

104 8.0 1.60 9.70 2.00 22.35 4.47 25.25 5.05

109 7.6 1.52 8.90 1.78 21.70 4.34 26.10 5.52

114 8.6 1.72 9.20 1.84 22.15 4.43 26.25 5.52

119 8.0 1.60 9.50 1.90 20.80 4.16 27.60 4.92

121 8.65 1.73 13.55 2.71 22.90 4.58 24.60 4.92

202 8.1 1.62 10.80 2.16 23.10 4.62 27.60 5.05

208 8.2 1.64 12.15 2.43 20.35 4.07 25.05 5.06

209 7.5 1.50 11.40 2.28 22.95 4.59 22.35 5.52

217 8.2 1.64 11.55 2.31 21.95 4.39 22.35 4.92

218 8.0 1.60 12.30 2.46 22.80 4.56 24.75 5.01

8082 8.40 1.68 7.76 1.84 23.13 4.63 25.95 5.19

8083 7.9 1.58 9.10 1.82 22.75 4.55 24.50 4.90

NWIBIBI 7.6 1.52 13.75 2.75 22.30 4.46 25.05 5.01

Table 7: Results for swelling power of starch.



The swelling power of the different starch varieties increased with increase in temperature. The weight (weight of the final mass) was divided with the

initial dry weight (5.0g) for all the starch varieties at the different temperatures. S.P = Swelling Power.

DISCUSSION

Gelatinization temperature for cassava starch of different varieties were found to be within the range of 68-71°C. This is similar to the result obtained

by Marbach et al., (1970) on cassava starch with a gelatinization temperatures within the range of 60°C t0 80°C. This suggests that the cassava starch

granules studied were swollen in the presence of water at the temperature between 68-71°C, which is quite low. Starch with low gelatinization

temperature is preferred for cooking.

The cooking quality of rice is associated with the starch gelatinization temperature (GT). Rice genotypes with low G.T have probably been selected for

their cooking quality by humans during domestication (Waters et al., 2006).

When the different varieties of starch were tested for paste clarity, it was observed that all the starch varieties were translucent at hot conditions,

whereas at cold conditions, all the varieties were opaque. Cereda and Woslacki, (1985) got similar result with starch. The clarity of the starch paste

suggests that cassava starch can be rightly applied in the Adhesive and Textile Industries.

The products of cassava are clear and suitable for combining with other colouring agents. Balogopalan, (2002) observed that cassava starch is preferred

for paste manufacture in view of its excellent cohesiveness and clarity, and its bland flavour allows it to be used in food packaging. Also, because the

cassava starch exhibits good clarity, it can be used in production of snacks in baking industries (International Starch Institute, 2000).

Result got from this research shows that swelling power increases with increase in temperature. Swelling power is the ratio of the final mass to the

initial mass obtained when starch is subjected to heating in excess of water (Takizawa et al., 2004). At very high temperatures such as 90°C or more,

when the swelling power obtained is also high, starch solution is mostly used for finishing textiles and in paper industries (Hill, 1952).

The pH values of the different varieties of starch were between 4.7 to 5.2. This shows that they are acidic. The slight variation from pH values obtained

maybe an indication of the presence of moulds or other impurities in the starch samples, as low pH indicates deterioration.

However, three varieties (NWIBIBI , 8082, and 8083) showed high acidic pH values of 3.0 for each. This may be due to the fact that these varieties were

commercial starches extracted in a different manner from the other starches. Such starches of very low pH will not be suitable in the paste industry, as

it may be detrimental to the human gum.

Acid factor is the measure of acid binding capacity of starch. This is the ability of starch to combine with acids. Some varieties such as 209 and 208 have

acid factors as low as 0.6 and 0.7 while others such as 8083, and NWIBIBI have acid factors as high as 1.3 and 1.45 respectively. The starch varieties

with high acid factors are applied in the formation of dextrins.



The ash content of most varieties studied fell between 25% to 42% while varieties like 8083 and NWIBIBI gave ash contents of 54% and 69%

respectively. However, results of ash content obtained by FAO (2001) gave ash content of native cassava as 0.8% and native potato as 2%. The increase

in ash content of the starch varieties may be as a result of too many impurities in the starch, which did not burn off completely.

Dyeing differential of starch is defined as the capacity of starch to absorb dye. The result obtained showed that all the starch varieties gave light blue

colours. Takizawa et al., (2004) obtained similar result while working with starch from cassava and corn. However, potato starch showed a black blue

colour, which may be associated with the presence of phosphate groups. This property (ability of starch to absorb dye) can be exploited in textile

industries where starch is used as finishing agents to obtain smooth fabrics and colour thickeners to obtain sharp and durable printed fabrics.

The relevance of this work to industries is much. Firstly, cassava starch with gelatinization temperature of 60-80°C can be exploited in making crispy,

crunchy snacks in the baking industry. In addition, the clear paste (and bland flavour) that is associated with cassava starch makes it most appropriate

in the food industries in the production of various snacks, ice cream and other dairy products. Also, the clarity of cassava starch paste enables its use in

the conversion industry as well as in the Paper, Pharmaceutical and Paste industries.

The swelling power of starch got at high temperature (60-80°C) can be exploited in the formation of gels and glues in the adhesive industry. This

property is also applied in the construction industry.

Furthermore, in the food industry, the pH test can be used to detect the presence of moulds and other impurities. In the different industries, starch of

low acid factor should be chosen except when starch is needed for dextrin formation. Finally, the ability of starch to absorb dyes could be exploited in

the textile industry.

CONCLUSION

In conclusion, starch has been very useful and will continue to play great roles in our industries. The range of food products employing starch in one

form or the other is almost without limit. Cassava starch has been commonly used in the industries because of its availability and low cost. In addition,

most of the physical and chemical properties of cassava starch gave it an edge over other types of starch.



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International Journal of Research and Reviews in Pharmacy