Journal of Atoms and Molecules

J. Atoms and Molecules / 2(5); 2012 / 387–393

Udoetok IA & Uffai ID

Research Article

Journal of Atoms and Molecules An International Online Journal ISSN – 2277 – 1247

EFFECT OF BLANCHING ON NUTRIENT AND ANTI-NUTRIENT LEVEL OF LEAVES OF SOME VARIETIES OF CASSAVA (Manihot esculenta C.) I. A. Udoetok*1, I. D. Uffia2 1

Chemistry Department, Faculty of Natural and Applied Sciences, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin L.G.A., Akwa Ibom State. 2 Biological Sciences Department, Faculty of Natural and Applied Sciences, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin L.G.A., Akwa Ibom State.

Received on: 21-09-2012

Revised on: 06-10-2012

Accepted on: 12–10–2012

Abstract: Random samples of leaves of three widely cultivated cassava varieties in Nigeria; TMS 30555, NR 8083 and TMS 30211 were collected from the Akwa Ibom State Agricultural Development Program (AKADEP) farm in Abak Local Government Area of Akwa Ibom State. The samples were dried, ground into powdery form and chemical analyses carried out on them. Proximate composition analyses revealed that these leaves contained appreciable amounts moisture, ash, lipid, crude protein, crude fiber and carbohydrate before and after blanching. Moisture was highest in NR 8083; 64.4% and lowest in TMS 30555; 58.0%. Ash content was highest in TMS 30555; 7.7% and lowest in TMS 30211; 6.3%. Lipid was highest in NR 8083; 10.0% and lowest in TMS 30211; 8.6%. TMS 30555 had the highest crude protein content; 33.8% while TMS 30211 had the lowest; 14.5%. Crude fiber was highest in TMS 30555; 5.1% and lowest in TMS 30211; 4.2%. Carbohydrate was highest in TMS 30211; 66.4% and lowest in TMS 30555; 44.7%. NR 8083 was richest in Vitamin A. Anti-nutrient analyses on the samples showed that they contain Hydrocyanic acid (HCN), Tannin, Phytate and Oxalate which were reduced as a result of blanching. The results also revealed that the samples contain appreciable amount of minerals with Calcium being the most abundant. The data obtained from this study therefore suggest that anti-nutritional properties of cassava leaves may be reduced through blanching thus making it a suitable supplement for micronutrients and vitamin A in diets if they are processed appropriately. * Corresponding author

Key Words: Nutrients, Anti-nutrients, Cassava

Udoetok Inimfon Abner,

leaves, proximate composition, Vitamin A, Minerals.

Email: [email protected] Tel: +2348029580124 All rights reserved© 2011

www.jamonline.in 387



Introduction:

cultures [3]. The cultivation of cassava is

Cassava (Manihot esculenta C.) is a perennial

increasing rapidly as productive new varieties

shrub which is grown throughout the lowland

are created and international markets for

tropics. It is the major staple food crop in

cassava products are developed. Cassava has

Nigeria supplying about 70% of the daily

gained increased industrial, economic and

calorie of about 50 million Nigerians [1].

nutritional importance over the years, because

Cassava is very closely associated with

of the multifarious uses of the starch-rich

extreme poverty because it is grown and eaten

tuber or roots and leaves.

mainly

by people with few economic

Since many people are already eating cassava

resources in Africa, Asia and Latin America.

leaves, the question is not whether to eat them

Cassava survives long droughts by shedding

but rather how to eat them. Encouraging the

its leaves and going dormant until rain

use of low HCN varieties is critical to this

returns. It is also a plant capable of growing in

effort. A grinding technique that ruptures cell

soils that is very acidic, low in nutrients and

wall followed by blanching may dramatically

high in toxic Aluminium compounds. These

reduce the total amount of HCN in the leaves.

growing conditions are increasingly common

Blanching is a cooking process wherein the

in degraded agricultural ecosystems of the

food substance, usually a vegetable or fruit, is

tropics. Its ability to produce food under such

plunged into boiling water, removed after a

harsh conditions make cassava “the poor

brief timed interval, and finally plunged into

man’s friend” [2].

iced water or placed under cold running water

In many cassava growing regions, the leaves

(shocked) to halt the cooking process. It was

are eaten as well as the roots. The value of

against this backdrop that we decided to

both the leaves and the roots is limited by the

evaluate the effect of blanching on the

presence of Hydrocyanic acid (HCN), a

concentrations nutrients, minerals and anti-

common plant toxin. Several cases of goats

nutrients in leaves of three widely cultivated

dying after eating cassava leaves actually

varieties of cassava (Manihot esculenta C.) in

magnify the problem. One would be tempted

Nigeria. The information obtained from this

to stay clear of cassava leaves altogether to

study shall be useful to the numerous

avoid any toxicity problems, except that the

consumers of cassava leaves as it will shade

plant has several important attributes as a leaf

more light on the nutritive value of these

crop. In addition to growing under difficult

varieties, the effect of blanching on the

conditions, cassava leaves are rich in protein,

nutritional and anti-nutritional properties of

vitamins and minerals that are needed to

the leaves and possibly recommend the

balance the heavy diet of many tropical All rights reserved© 2011




varieties that are most appropriate for use as a

Analyses of nutritional and anti-nutritional

leafy vegetable.

values

Experimental:

Nutritional values for the samples were

Sample collection and Treatment

determined before and after blanching. The

Random samples of leaves of the three most

methods adopted by [9] [10] [11] [3] and [12]

widely cultivated cassava in Akwa Ibom State

were used. The anti-nutrients content was

(TMS 30555, NR 8083 and TMS 30211) were

estimated by standard procedures described

collected from Akwa Ibom Agricultural

by [13] [14] [15] and [7] All analyses were

Development Program (AKADEP) farm in

carried out in triplicate.

Abak Local Government Area of Akwa Ibom

Results and Discussions

State. All the samples were cultivated in the

Proximate composition

humid tropical rainforest zone where the rains which

fall

between

March

and

September/October average between 1150 and 2000mm annually. All samples were a composite of fully expanded and mature leaves. About 2kg leaves collected from each of the varieties were thoroughly mixed, rinsed with distilled water and dried at 60oC in an oven for three hours. The dry samples were ground to fine powder, passed through a 30mm mesh sieve and stored in air tight containers, from where required amounts were taken for analyses.

The proximate composition of the samples is reported in table 1. These results reveal that before blanching, the moisture content of the samples was between 58.0% and 64.0%, Ash content was between 6.3% and 7.7%, crude fat was between 8.6% and 10.0%, and crude protein was between 14.5% to 33.8%, crude fiber

was

between

4.2%

to

5.1%,

carbohydrate was between 44.7% to 66.4% and caloric value was between 392.3 kcal to 406.0kcal.

Moisture

content

and

crude

fat(lipid) was highest in NR 8083 before blanching and was still highest in the same

Blanching

sample after. It therefore suggests that this

All determinations were carried out before

sample with the highest moisture may be the

and after blanching. For blanched samples,

most succulent and susceptible to decay.

the blanching was carried out according to

Ash content of leaves reflect its mineral and

standard method described by [4].

elemental composition, consequently, the

Determination of vitamins

leaves of TMS 30555 with the highest ash

The vitamin A contents of the samples were

content may be the richest in mineral and

determined by standard methods described by

elemental composition. Crude fiber and

[5] [6] [7] and [8]. All rights reserved© 2011

protein were also highest in TMS 30555 thus www.jamonline.in 389



corroborating the fact that this sample may

the treatment. This parameter was highest in

have the highest mineral and elemental

NR 8083 before and after blanching. Tannin

composition. Crude fiber is the insoluble

had the least concentration of all the anti-

material remaining after severe acid and base

nutritional

hydrolysis.

concentrations of 16.0mg/kg, 14.8mg/kg and

Carbohydrate content was highest in TMS

10.2mg/kg in TMS 30555, NR 8083 and TMS

30211 with a value of 66.4%. From the above,

factors

analyzed.

It

had

30211 respectively before blanching and

it may be deduced that blanching adversely

4.8mg/kg, 4.0mg/kg and 5.2mg/kg after

affects the proximate composition of the

blanching respectively. The concentration of

samples, since there were reduction in the

phytate in the samples ranged between

concentration of all the proximate parameters

190mg/kg and 220mg/kg before blanching and

after the treatment.

180.1mg/kg

to

200.0mg/kg

after

blanching. The above results reveal that Antinutrient composition

blanching may be a veritable tool for reducing

The results for anti-nutritional factors for the

the antinutrient content of cassava leaves.

leaves

are

Reference [18] reported the decrease in anti-

presented in Table 2. The anti-nutritional

nutritional of asparagus been flower after

factors are the major factors limiting the wide

soaking, blanching and cooking. [19] also

use of many plants as they are present in the

reported that blanching reduced both the

plants naturally and capable of eliciting

nutritional and anti-nutritional values of non-

deleterious effects in man and animals [16].

conventional vegetables.

before

and

after

blanching

The anti-nutritional factors; oxalate, HCN,

Vitamin A content of samples

tannin, and phytate were present in varying amounts in all the vegetables. Phytate has

Vitamins are potent organic compounds found

been reported to reduce the bioavailability of

in certain food and perform specific and vital

trace element and minerals [17] and [16].

functions in body chemistry [20]. Our body

HCN was highest in TMS 30211 with a value

needs them for growth, function, energy,

of 270.0mg/kg but reduced drastically to

tissue repair and waste removal. They are like

62.0mg/kg, showing a percentage reduction of

electric sparks which help to run human

77.03%.

motors [21].

Oxalate

concentration of factors.

Its

had all

the

concentration

the

highest

Vitamin A among other

anti-nutritional

functions help to regulate cell development,

ranged

promotes bone and teeth development, and

from

5000mg/kg to 7590mg/kg before blanching

boosts the body immune system.

and ranged from 485mg/kg to 680mg/kg after

All rights reserved© 2011




The result of this study (table 2) shows that

affect the potentials of the leaves as a leafy

these varieties of cassava leaves are rich in

vegetable. It may be concluded that cassava

vitamin A before and after blanching. NR

leaves may be blanched and used as leafy

8083 had the highest value of 1137673.0

vegetables because of it rich mineral and

mg/kg before blanching and still had the

nutritional values.

highest after blanching.

References

Mineral Composition of samples

1. O. L. Oke (1968). Cassava as a Food in

The concentrations of minerals in the samples are recorded in table 4. This results show that NR

8083

had

the

highest

mineral

concentration while TMS 30211 had the least.

Nigeria. World Rev. Nutr. Dietec. 9:227. 2. D. J. Rogers (1963). Studies on manihot esculenta C. and related species. Bull Torrey Bot. Club, 90 (1): 43 – 45.

Concentration of the minerals in TMS 30555 was as follows: Ca was 2905 ± 0.08 mg/kg, Mg was 238 ± 0.22 mg/kg, Zn was 730 ± 0.12 mg/kg, K was 680 ± 0.09 mg/kg, P was 2420 ± 0.17mg/kg while Fe. 121 ± 0.15mg/kg. The result also reveals that Ca had the highest concentration of all the minerals. This result is

3. I. A. Udoetok (2001). A comparative study of the Nutrient and Antinutrient content of leaves of some varieties of Cassava. (manihot esculenta C). A B.Sc. thesis, University of Uyo, Nigeria. 4. G. I. O. Badifu, E. M. Okeke (1992).

corroborated by the fact that crude protein,

Effect

ash and crude fibre were highest in this

Hydrocyanic 205 Acid and Saponin of our

sample. It may be deduced from the above

Nigeria Leafy Vegetables. J. Agric. Sci.

result that these varieties of cassava leaves

Technol. pp. 71-75

have high concentration of minerals.

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on

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Modibbo,

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2461-2463.


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Umaru

(2006).


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Table 1: Proximate composition of the samples Sample

Moisture (%) TMS 30555(a) 58.0 ± 0.12 TMS 30555(b) 50.0 ± 0.20 64.4 ± 0.08 NR 8083 (a) 62.2 ± 0.10 NR 8083 (b) TMS 30211 (a) 61.1 ± 0.25 TMS 30211 (b) 59.5 ± 0.20 (a) – unblanched sample

Ash (%) 7.7 ± 0.15 6.1 ± 0.12 6.6 ± 0.22 6.0 ± 0.15 6.3 ± 0.14 5.8 ± 0.12

Fat (lipid) (%) 8.7 ± 0.24 7.9 ± 0.14 10.0 ± 0.12 8.6 ± 0.17 8.6 ± 0.15 6.8 ± 0.16

Crude Protein (%) 33.8 ± 0.12 28.2 ± 0.18 32.9 ± 0.17 27.2 ± 0.16 14.5 ± 0.14 11.7 ± 0.10

Crude Fibre (%) 5.1 ± 0.18 2.5 ± 0.21 4.4 ± 0.09 2.2 ± 0.18 4.2 ± 0.10 2.1 ± 0.22

Carbohydrate (%) 44.7 ± 0.16 22.5 ± 0.17 46.1 ± 0.15 23.5 ± 0.21 66.4 ± 0.10 33.2 ± 0.12

(b) - blanched sample Table 2. Antinutrient composition of the samples (mg/kg) Sample TMS 30555(a) TMS 30555(b) NR 8083 (a) NR 8083 (b) TMS 30211 (a) TMS 30211 (b)

HCN 108.0 ± 0.08 22.0 ± 0.02 162.0 ± 0.01 48.0 ± 0.01 270.0 ± 0.03 62.0 ± 0.03

Oxalate 5280.0 ± 0.24 540.0 ± 0.20 7590.0 ± 0.21 680.0 ± 0.21 5000.5 ± 0.23 485.0 ± 0.25

Tannin 16.0 ± 0.01 4.8 ± 0.01 14.8 ± 0.02 4.0 ± 0.02 10.2 ± 0.01 5.2 ± 0.01

Phytate 190.0 ± 0.01 180.1 ± 0.01 215.2 ± 0.02 192.1 ± 0.02 220.4 ± 0.01 200.0 ± 0.01

(a) – unblanched sample (b) - blanched sample

Table 3: Vitamin A content of samples Sample TMS 30555(a) TMS 30555(b) NR 8083 (a) NR 8083 (b) TMS 30211 (a) TMS 30211 (b)

Concentration (mg/kg) 814516.1 602345.5 1137673.0 923564.8 936059.9 543283.7

(a) – unblanched sample (b) - blanched sample

Table 4: Mineral composition of samples Sample TMS 30555 NR 8083 TMS 30211

Ca (mg/kg) 2905 ± 0.08 2202 ± 0.12 1802 ± 0.20


Mg(mg/kg) 238 ± 0.22 215 ± 0.15 115 ± 0.12

Zn (mg/kg) 730 ± 0.12 680 ± 0.24 540 ± 0.16

K (mg/kg) 2420 ± 0.17 1440 ± 0.12 2000 ± 0.10

P (mg/kg) 680 ± 0.09 520 ± 0.18 600 ± 0.22

Fe (mg/kg) 121 ± 0.15 110 ± 0.16 104 ± 0.12
