Effect of fermentation period on cyanide reduction in garri flour and

comparison with some selected samples marketed in aba, Nigeria.

Keywords: Cassava, Cyanide, Garri, Fermentation.

ABSTRACT: Garri is the most popular form in which cassava is consumed in Nigeria. This research studied the effect of fermentation period on cyanide reduction in garri flour (white and yellow garri samples) and comparison with some selected samples marketed in Aba, Nigeria. The cyanide content of the various garri samples were estimated by alkaline picrate paper spectrophotometric method. The results showed that the cyanide contents decreased significantly (p<0.05) with the length of fermentation period of the grated cassava mash from 1st to 4th days. Though there was a decrease in cyanide concentrations between the 4th and 5th days, they were not significant (p>0.05). Cyanide concentrations of the market purchased garri samples had 14.37±0.05 to 36.32±0.1 mg/kg and 18.37±0.05 to 29. 68±0.05 mg/kg in the white and yellow garri samples respectively. These values indicated that about 50% of the market purchased garri samples showed varying cyanide concentrations of 1st to 2nd day’s fermentation. This study has revealed the need to educate the public on the imminent danger of inadequate fermentation of garri flour and it will subsequently strengthen the moral norms of the producers to adapt to normal period of 5 to 6 days.

152-156 | JRA | 2013 | Vol 2 | No 1

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Journal of Research in

Agriculture An International

Scientific Research Journal

Authors:

Ukpabi Chibueze F1,

Emeghebo Ngozi1 Ukpabi

Emmanuel2 and Emole Eke

Chukwu2.

Institution:

1. Department of

Biochemistry, Abia State

Polytechnic, Aba.

2. Department of Chemistry,

Abia State Polytechnic, Aba.

Corresponding author:

Ukpabi Chibueze F.

Email:

ukpabichibueze@yahoo.com

Phone No:

0806670705.

Web Address:

http://www.jagri.info

documents/AG0033.pdf.

Dates: Received: 03 Dec 2012 Accepted: 05 Dec 2012 Published: 05 Apr 2013

Article Citation: Ukpabi Chibueze F, Emeghebo Ngozi, Ukpabi Emmanuel and Emole Eke Chukwu. Effect of fermentation period on cyanide reduction in garri flour and comparison with some selected samples marketed in aba, Nigeria. Journal of Research in Agriculture (2013) 2(1): 152-156

An International Scientific Research Journal

Original Research

Journal of Research in Agriculture

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INTRODUCTION

Food products prepared from cassava (Manihot

species) are the staple diet consumed in tropical Africa.

Products such as garri, fufu and tapioca are very popular

in Nigeria. These food products play major roles in

efforts to alleviate food crisis because of their efficient

production of food energy, year- round availability and

food systems in Africa. In recent times changes have

raised to increase cassava productivity, new varieties, use

modern irrigation methods, chemical fertilizers and

herbicides. It is estimated that the crop production is

about 40% of all calories consumed in Africa (Roa et al.,

1997).

Garri flour is the most popular processed food

from cassava in Nigeria. In garri production, fresh roots

are peeled and grated. The grated pulp is put in jute and

the jute are placed under heavy stones or pressed with a

hydraulic lock between wooden platforms for 5 to 6 days

to express excess liquid from the pulp while it is

fermenting. The dewatered and fermented lumps of pulp

are sieved and roasted. Palm oil may be added to give a

light yellow colour to the garri. When palm oil is not

added a white garri is produced. Nowadays, the

processing techniques of garri has moved from simple

processing to complicated procedures which involve

semi-mechanised and intergrated accelerated methods

(Odoemelam, 2005).

Recent studies have shown that garri is widely

consumed as food in several parts of Nigeria (Harbor and

Ogundu, 2009; Odoemelam, 2005). Garri can be eaten

dry or soaked in water as “Eba” and consumed with

soups. “Eba” is a very popular food in Nigeria and is

gaining popularity in many African countries because of

its fast and easy reconstitution into a convenient food.

The major factor that limits the use of cassava as food is

that it is a significant source as cyanogenic glucosides

(Enidiok et al., 2008). These cyanogenic glucosides are

widely distributed in the plant, with higher

concentrations in the leaves and root peel and lower

concentrations in the root parenchyma (inside the root)

(Cardoso, 2005). The major traditional method of

reducing cyanide in garri is by fermentation over periods

of about 5 to 6 days (FIIRO, 2006). Although, other steps

such as peeling, washing, grating, drying, dewatering,

milling and roasting can also influence the level of

residual cyanide in cassava products (Omoike and

Adediran, 1991).

Due to the imminent danger and high toxicity of

several cassava varieties, the Codex Alimentarius

Commission has set the limits of 10 mg/kg hydrocyanic

acid for cassava flour and cassava starch (FAO/WHO,

1991).The expansion of food markets has forced some

countries such as Indonesia to introduce a sanitary

control to regulate the entry of food products (Djazuli

and Bradbury, 1999). Other countries such as Colombia

have set a regulation for cyanogenic glycosides levels in

animal feed (ICONTEC, 2002). Few comparative studies

have been carried out on the effect of fermentation

period on cyanide reduction in cassava products, with the

assumption that the commercially sold cassava products

have a high level of residual cyanide due to the reduced

length of fermentation period of the cassava pulp by the

producers in a bid to increase turnover and hence,

maximize profit (Odoemelam, 2005). This assumption

represents a health risk because cassava consumption has

been associated with several types of pathological

disorders (Enidiok et al., 2008). Health risks whether at

the global, national or local level is a result of multiple

major human-related factors (Moghaddam et al., 2012).

Data on hydrogen cyanide levels in garri will help in

formulating public health policies and strengthen the

moral norms of the processors.

This work has two objectives: the first is to

evaluate the effect of fermentation period on cyanide

reduction in garri flour. The second objective consists in

comparing the results obtained after analyzing the above

samples with some selected garri samples marketed in

Aba Nigeria.

153 Journal of Research in Agriculture (2013) 2(1): 152-156

Chibueze et al.,2013

MATERIALS AND METHODS

Plant material

Cassava tubers were obtained from National

Root Crop Research Institute Umudike (NRCRI) and

were identified as NR8082.

Sample preparation

10.0 kg of fresh tubers were peeled, washed with

water and grated in an engine-power machine made for

that purpose. The mashed cassava pulp was divided into

two portions A and B. The portion B was mixed with

palm oil while the other portion left as such. The two

samples were separately packed into two different jute

bags for dewatering using local fabricated mechanical

press.

Each sample was further divide into 5 portions

and was fermented at the interval of 1, 2, 3, 4 and 5 days

respectively. The fermented and semi-drying cassava

pulp was sieved and subsequently roasted in a circular

frying pan with continuous stirring until the meal

become light and crisp. In addition, 20 garri samples

(10 white and 10 yellow) were bought from the major

markets in Aba, Abia State Nigeria. The garri samples

were randomly selected from these markets over a period

of three days.

Analysis

Cyanide content of the garri samples were

determined by alkaline picrate paper spectrophotometric

method as described by Balagopalan et al., (1988) and

Onwuka (2005).

Each garri sample (1.0 g) was homogenized at

room temperature in 50ml of distilled water for 60 mins

in a 100 ml beaker. An alkaline picrate paper

(whatman No1 strip) was hung over the test sample in

the conical flask for 18 h at room temperature. The

alkaline picrate paper was removed and eluted with

60 ml distilled water into a 100 ml beaker. The

absorbance of the eluted sample solution was measured

spectrophotometrically at 540 nm against the reagent

blank.

A standard solution of potassium cyanide was

treated as the test sample and the absorbance was

measured at the same wavelength. The cyanide

concentration was subsequently calculated.

RESULTS AND DISCUSSION

The hydrogen cyanide contents of white and

yellow garri and effect of length of fermentation

are presented in Table 1. Cyanide contents of the white

and yellow garri samples on the 1st day recorded

the highest concentration values of 31.44±0.03 and

35.25±0.05 mg/kg respectively. Similarly, on the 5th day,

the results also indicated significant reduction (p<0.05)

of 13.78±0.05 and 11.23±0.05 mg/kg respectively. The

level of cyanide reduction in both garri samples were

significantly different (p<0.05) between the 1st and 4th

days of fermentation. However there was no significant

difference (p>0.05) observed between the 4th and 5th days

of the fermentation. It can be deduced from the result

that, the longer the fermentation period less the residual

cyanide. The reduction may be attributed to the

breakdown of the cyanogenic glycosides in the cassava

pulp during the various steps involved in the production

especially fermentation. Therefore, cassava must be

processed adequately in order to reduce cyanide

contents. This supports the earlier findings by

Odoemelam (2005) that significant reduction (p<0.5) in

cyanide level was observed over period of 3 days of

fermentation.

Journal of Research in Agriculture (2013) 2(1) : 152-156 154

Chibueze et al.,2013

Table 1 The HCN contents of white and yellow garri

Samples and effect of length on fermentation

Fermentation

period

Level of HCN

White garri

(mg/kg)

Yellow garri

(mg/kg)

1 day 31.44± 0.03 35.25±0.05

2 days 22.88± 0.05 20.66± 0.03

3 days 16.46± 0.03 14.29± 0.00

4 days 13.81± 0.05 12.0.6±0.05

5 days 13.78±0.05 11.23± 0.05

Results are expressed as means of triplicate

determination ±S.E

Table 2 shows the cyanide contents of market

purchased garri samples, obtained from different

locations in Aba, Abia State Nigeria. These market

purchased garri samples were reported fermented for 3 to

4 days by the sellers and the cyanide levels ranged from

14.37±0.05 to 36.32±0.10 mg/kg on dry matter basis.

The wide variation in the cyanide contents of the market-

purchased garri samples showed that 4, 2, 2 and 2 white

garri samples fall within the 1st, 2nd, 3rd and 4th days of

fermentation respectively while 0, 5 and 5 yellow garri

samples fall within the 1st, 2nd and 3rd days respectively.

These values indicated that about 50% of the market

purchased garri samples showed varying cyanide

concentrations of 1st to 2nd day’s fermentation of the

reference garri samples as shown in Table 1. The present

finding supports the earlier observation that the cyanide

levels in the market purchased garri samples had higher

levels than the residual cyanide levels in the 3 days

fermented reference garri samples (Odoemelam, 2005).

This situation could probably arise from the

reduced lengths of fermentation periods therefore, it is

necessary to discourage the practice of reducing

fermentation period in attempt to increase sales. The

result represents a health risk because cassava

consumption with high concentrations of cyanigenic

glycosides causes tropical ataxic polyneuropathy in

individuals over 40 years old and also exacerbates the

conditions of goiter and cretinism in women and children

with a low iodine intake (Delenge et al., 1994; Haque

and Bradbury, 2004).

CONCLUSION

This result indicated that about 50% of the

market purchased garri samples showed varying cyanide

concentrations indicating fermentation period of 1 to 2

days. The work agrees with Odoemelam, (2005) that

campaign to educate the public on the danger of this

unwholesome practice is paramount.

ACKNOWLEDGMENT

The authors are grateful to the management of

National Root Crops Research Institute, Umudike for the

assistance rendered in the running of the analysis.

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Balagopalan CG, Padmaja G, Nanda SK, Moorthy

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155 Journal of Research in Agriculture (2013) 2(1) : 152-156

Chibueze et al.,2013

Table 2 The HCN contents of market purchased

garri samples

Samples

Level of HCN

White garri

(mg/kg)

Yellow garri

(mg/kg)

Sample A 16.32±0.03 29.30± 0.03

Sample B 32.27±0.08 18.67± 0.03

Sample C 33.20±0.05 18.37± 0.05 Sample D 14.37±0.05 29.69± 0.05

Sample E 36.32± 0.1 19.97±0.09

Sample F 18.04±0.05 19.28± 0.04

Sample G 19.12±0.04 20.05± 0.06

Sample H 23.08±0.06 22.37± 0.08

Sample I 28.88±0.05 24.01± 1.02

Sample J 34.58±0.12 27.36± 8.05

Results are expressed as means of triplicate

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Journal of Research in Agriculture (2013) 2(1) : 152-156 156

Chibueze et al.,2013

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