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© 2021 Conscientia Beam. All Rights Reserved. 

BACTERIOLOGICAL QUALITY AND CYANIDE CONTENTS OF DIFFERENT CASSAVA 
PRODUCTS PROCESSED IN BENUE STATE FOR USE AS FOOD FOR MAN OR 
FEEDSTOCK FOR ANIMALS   

 

 

 Alphonso. O. 
Nwankiti1 

 Innocent. O. 
Ogbonna2+ 
Christopher O. Eche3 

 

1,3Department of Crop and Environmental Protection, Federal University of 
Agriculture, Makurdi, Nigeria. 
2Department of  Microbiology, Federal University of  Agriculture, Makurdi, 
Nigeria. 

 
 
 

 
(+ Corresponding author) 

 ABSTRACT 
 
Article History 
Received: 10 December 2019 
Revised: 30 December 2020 
Accepted: 26 March 2021 
Published: 13 April 2021  
 

Keywords 
Bacteriological quality 
Cassava products 
Cyanide 
Total viable bacterial count  
Total coliform count. 

 
The bacteriological profiles of the different cassava products were investigated. Ground 
cassava samples, serially diluted with sterile normal saline were cultured in different 
sterile bacteriological media. Hydrogen cyanide content was determined by 
spectrometric method. Colonies isolated from the different locations were statistically 
the same for total viable bacterial counts (TVBC). Cassava peels had the highest values 
of TVBC (4.456 log10CFU/g) TCC (3.025 log10CFU/g) EC (1.663) and SA counts. Gari 
had the lowest values of TVBC (3.193) TCC (2.580) EC (not isolated) and SA counts. 
The traditionally processed cassava products showed no statistically significant 
differences (p<0.05) with the mechanically processed products except in fufu. The total 
viable bacterial count was highest in cassava products dried along the roadside (6.980 
log10CFU/g) and lowest oven-dried cassava products (2.763 log10CFU/g). No 
Salmonella and Shigella spp. were isolated in most of the assayed cassava products. The 
identified storage places of the cassava products did not significantly impact any 
difference on the bacterial load. There was a progressive decrease in the cyanide 
contents from cassava peels to cassava chips to fufu and least in gari. The highest 
hydrogen cyanide concentration of 14.50 mg/kg was recorded in cassava peels and was 
higher than 10 mg of HCN/kg body weight recommended by WHO. Gari had the least 
content of 2.25 mg/kg. The study provides information on potential infections and 
toxicities due to the microorganisms and cyanide level.  
 

Contribution/Originality: This study is one of the very few studies which have investigated bacteriological 

quality of different cassava products processed in Benue State for use as food for man or feedstock for animals.  

 

1. INTRODUCTION 

Cassava (Manihot esculenta Crantz) is a basic root crop that is utilized globally as food for humans and feed for 

animals. It serves as a major source of carbohydrates for millions of people especially the low income earners in the 

tropics and sub-tropical countries [1]. In terms of agricultural food security, it is the most robust and important 

food crop in Nigeria [2] and Nigeria is the world’s largest producer for over a decade [3].     

In Nigeria, cassava tubers are processed and consumed in different forms, namely: cassava chips which is 

processed for flour, gari and cassava peels used for feedstock for animals. Other economic uses of cassava include 

making fufu, confectionaries, glues, monosodium glutamate, sweeteners, pharmaceuticals and textiles [2]. However, 

Current Research in Agricultural Sciences 
2021 Vol. 8, No. 1, pp. 47-55. 
ISSN(e): 2312-6418 
ISSN(p): 2313-3716 
DOI: 10.18488/journal.68.2021.81.47.55 
© 2021 Conscientia Beam. All Rights Reserved. 

 
 
 

 
 
 

 

 
 
 
 

https://orcid.org/0000-0002-6007-3979
https://orcid.org/0000-0003-3428-6177
https://www.doi.org/10.18488/journal.68.2021.81.47.55


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48 

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most indigenous low-income earners of the society use the cassava in the form of gari, fufu, chips and the peels are 

consciously or unconsciously served to ruminant animals as feedstock.      

Microorganisms are ubiquitous and are found virtually everywhere. They have a wide range of carbon 

substrates for growth and cellular metabolism. In cassava production systems, many microorganisms have been 

associated with its contamination including fungi [4, 5] and bacteria [2, 5] rendering it a public health issue.  

Microbial quality/ public health issues relating to consumption of cassava products include the following. 

Cassava contains cyanogenic glucoside which is made up of linamarin and lotaustrain [6]. The quantity of 

cyanogenic glucoside is dependent on the cassava variety [7]. Diseases arising from excessive consumption of 

cassava with high cyanide contents include but not limited to cretinism, goiter, neuropathy and tropical diabetics 

Nhassico, et al. [8]. WHO [9] stipulated the limits of cyanogenic glucoside in consumed food to which if exceeded, 

becomes adverse. The implication of consumption of cassava product with high cyanide content is well known. The 

present work investigated the bacteriological quality cyanide compositions of different cassava products sold in 

Benue State for use as food for man or feedstock for animals. 

 

2. MATERIALS AND METHODS 

2.1. Collection of Cassava Product Samples 

Survey was carried out in Benue State in November 2018 in three local government areas of the state to assess 

the techniques deployed in cassava processing, drying and storage in the various places visited and in addition 

determine the microbial load.  Multistage sampling involving purposive and random methods were used. Cassava 

producing communities in Benue State were selected and then random samples were collected from livelihoods in 

the selected communities. 

 

2.2. Bacteriological Analysis 

2.2.1. Preparation of the Cassava Sample 

The different cassava samples were prepared by weighing one gram of each of the granulated cassava (ground 

in sterile mortar and pistil) product in 9 mL of peptone water. These were the stocks used for the inoculation of the 

different isolation media below. The stocks were appropriately diluted prior to use for inoculation.  

 

2.2.2. Nutrient Agar 

Nutrient Agar (NA) was used for the determination of Total Viable Bacterial Counts (TVBC). Nutrient Agar 

(HiMedia Laboratories Pvt. Ltd, India) was prepared by weighing 14.0 g of NA powder into a 500 mL conical flask 

and dissolving in distilled water.  This was brought to 500 mL volume and was heated and shaken intermittently to 

mix.  Thereafter, it was tightly plugged with quality cotton wool, and was covered with aluminum foil and 

sterilized by autoclaving at 121 oC for 15 minutes.  This was allowed to cool to 40 - 50 oC before dispensing into 

Petri dishes. The medium was allowed to solidify on the plate. A 0.1 mL of appropriately diluted sample was 

introduced into the sterile medium and evenly spread using a sterile glass spreader. This was subsequently 

incubated at 37 oC for 24 h. Colonies that form on the incubated plates were counted using a digital colony counter 

and results recorded. 

 

2.2.3. MacConkey Agar  

Total Coliform Counts (TCC) was determined using MacConkey Agar (MA). MacConkey Agar (HiMedia 

Laboratories Pvt. Ltd, India) was prepared by dissolving 27.6 g of MA powder in 500 mL of distilled water until a 

homogenous mixture was achieved.  This was possible through gentle heating with continuous shaking.  The 

medium was sterilized by autoclaving at 121 oC for 15 minutes.  Thereafter, the sterile MA was allowed to cool to 

40 – 50 oC before dispensing to sterile Petri dishes. The medium was allowed to solidify and a 0.1 mL of 



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appropriately diluted sample was introduced into the sterile medium and evenly using a sterile glass spreader. This 

was subsequently incubated at 37 oC for 48 h. Colonies that form on the incubated plates were counted using a 

digital colony counter and results recorded. 

 

2.2.4. Xylose Lysine Deoxycholate Agar (XLDA)  

Confirmation and enumeration of Salmonella and Shigella spp were done on XLDA. Xylose Lysine 

Deoxycholate Agar (XLDA) was prepared according to the manufacturer’s specifications. A 500 mL XLDA (27.7 g 

of powder) medium was sterilized in a 1 L Erlenmeyer flask by bringing to boil over a heater. This was allowed to 

cool to 40 – 50 oC before dispensing to Petri dishes. Prepared medium was inoculated with a 0.1 mL of 

appropriately diluted sample and was spread evenly on the plate. This was subsequently incubated at 37 oC for 24 h 

and emergent colonies were counted using a digital colony counter. 

 

2.2.5. Eosin Methylene Blue Agar  

The Escherichia coli content of the sample was determined using Eosin Methylene Blue Agar (EMBA). Eosin 

Methylene Blue Agar (TM Media, Titan Biotech Ltd, BHIWADI, Rajasthan, India) was prepared by dissolving 

18.0 g of EMBA in 500 mL of distilled water.  The dissolution was accompanied by gentle heating and was 

thereafter sterilized by autoclaving at 15 psi (121 oC) for 15 minutes.  Upon cooling to 45 – 50 oC, the medium was 

dispensed into sterile Petri dishes. A 0.1 mL of appropriately diluted sample was introduced into the sterile medium 

and was evenly spread. This was subsequently incubated at 37 oC for 24 h. Colonies that form on the incubated 

plates were counted using a digital colony counter and results recorded. 

 

2.2.6. Mannitol Salt Agar  

Staphylococcus aureus (SA) was isolated in Mannitol Salt Agar (MSA). Mannitol Salt Agar (HiMedia 

Laboratories Pvt. Ltd, India) was prepared by suspending 55.6 g MSA in distilled water.  It was homogenized with 

frequent heating and agitation until completely dissolved.  The MSA was sterilized by autoclaving at 121 oC for 15 

minutes. This was allowed to cool to 50 oC before pouring into sterile Petri dishes. A 0.1 mL of appropriately 

diluted sample was introduced into the sterile medium and evenly spread using a sterile glass spreader. This was 

subsequently incubated at 37 oC for 24 h. Colonies that form on the incubated plates were counted using a digital 

colony counter and results recorded. 

 

2.3. Biochemical Identification of the Isolates  

Triple sugar iron (TSI), urease test, oxidase, coagulase and catalase in addition to indole test, methyl red, 

Voges-Proskauer, and citrate utilization (IMVIC) were used to characterize the bacteria following the protocol 

documented by Cheesbrough [10].  

 

2.4. Determination of Hydrogen Cyanide Concentration 

Hydrogen cyanide concentration was determined by modifying the methods by Ezeh, et al. [11] and Sawyerr, 

et al. [12] as presented below. Two grams of the cassava powder was added to 20 mL of sterile distilled water in a 

conical flask, shaken to form a paste, stoppered and allowed to stand at room temperature (28±2 oC). The paste was 

filtered (Whatman No.1) after addition of further sterile distilled water. The filtrate was made up to 50 mL volume. 

This was kept in the refrigerator (4 oC) until used.  

 

 

 

 



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2.4.1. Alkaline Picarate Preparation 

Alkaline picarate was prepared by dissolving 1 g of picric acid and 2 g of sodium trioxo carbonate in a small 

volume of minimally warm water. This was thereafter brought to a 100 mL volume and stored in an amber-colored 

bottle in the fridge (4 oC) until used.  

To determine the cyanide content, 4 mL of alkaline picarate was added to a 5 mL quantity of the filtered 

cassava solution. This was warmed for 5 min in a water bath set at 5 oC for brown color development. Thereafter, 

this was allowed to cool and read against a blank at 490 nm (UV-Spectrophotometer). The blank was prepared by 

adding 1 mL water to 4 mL of alkaline picarate solution. The cyanide concentration expressed as mg/kg was 

extrapolated from a standard curve. 

 

2.5. Statistical Analysis 

Descriptive statistics and one-way analysis of variance (ANOVA) were performed using SPSS (version 16.0). 

 

3. RESULTS 

Results of the bacteriological profiles of the different cassava products are shown below. Cassava chips, fufu, 

garri and cassava peels had numerically different bacterial loads.  Table 1 presents the levels of bacterial load with 

respect to locality from where the products were sourced. The Table reveals that Ikyose of Katsina-Ala (KA) and 

Mbahaya of Makurdi Local Government had the highest TBVC value of 4.326 log10CFU/g. The TVBC of 3.215 got 

from samples from Ehurekpe in Oju was the lowest. However, most of the TVBC values were statistically 

homogeneous. The mean total coliform count (TCC) was highest (2.763 log10CFU/g) in Katsina-Ala (KA) (Ikyose) 

and lowest in Adaka (1.806 log10CFU/g) of Makurdi Local Government. Escherichia coli count (ECC) used as 

indicators of food quality was highest (1.681 log10CFU/g) in samples from KA area of KA local Government but 

was not isolated in some areas of Makurdi and Oju. Cassava peel samples from Makurdi had Salmonella sp (1.00 

log10CFU/g) as opposed to all other locations where Salmonella and Shigella were not isolated. 

 
Table-1. Influence of location on the bacterial quality (log10CFU/g) of cassava peels. 

Local Govt. Locations TVBC TCC SAL SHI EC SA 

Katsina-Ala Katsina-Ala 3.729 2.335 - - 1.681 1.556 
Agasoma 4.050 2.505 - - 1.415 1.681 
Agoasu 4.269 2.620 - - 1.531 1.556 
Ikyose 4.326 2.763 - - 1.505 1.748 

Makurdi Tionsha 4.215 2.964 1.000 - 1.663 2.924 
Mbahaya 4.326 2.256 - - 1.505 1.681 

Yagba 4.107 2.601 - - 1.204 1.707 
Adaka 3.982 1.806 - - - - 
Mbayo 4.065 2.579 - - 1.342 - 

 
Oju 

Obolori 3.934 2.756 - - 1.204 1.672 
Ihiejwo 4.256 2.556 - - 1.326 2.819 

Ehurekpe 3.215 2.065 - - - 1.833 
Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = E. coli, SA = S. aureus. 

 
Table-2. Effect of location on the bacterial quality (log10CFU/g) of cassava chips. 

Local Govt. Locations TVBC TCC SAL SHI EC SA 

Katsina-Ala Katsina-Ala 3.729 2.193 - - 1.301 1.204 
Agasoma 3.415 2.025 - - 1.114 1.602 
Agoasu 3.672 2.305 - - 1.079 1.477 

Ikyose 3.556 2.025 - - 1.091 1.415 

Makurdi Tionsha 3.833 2.121 - - 1.301 1.903 
Mbahaya 3.604 2.009 - - 1.176 1.204 

Yagba 3.215 2.220 - - 1.146 1.326 
Adaka 3.782 1.968 - - - - 
Mbayo 3.256 2.204 - - 1.231 0.954 



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Oju Obolori 3.672 2.093 - - 1.114 1.699 
Ihiejwo 3.156 2.162 - - 1.301 1.778 

Ehurekpe 3.065 2.215 - - - 1.231 
Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = E. coli, SA = S. aureus. 

 

Effect of location on the bacterial quality (log10CFU/g) of cassava chips is presented in Table 2. The TVBC was 

highest (3.833) in cassava chips from Tionsha in Makurdi Local Government Area and least (3.065) in samples from 

Ehurekpe in Oju. The TCC values obtained from cassava chips was highest (2.305) from Agossu in KA and lowest 

(1.968) in samples from Adaka in Makurdi. Salmonella and Shigella spp. were not isolated from the cassava chips 

from the locations at the time of the study. The three locations had similarly the highest (1.301) EC contaminations. 

Escherichia coli was not isolated in cassava chips from Adaka and Ehurekpe. Staphylococcus aureus was highest (1.903) 

in MA area of MA local Government Area. 

 Effect of location on the bacterial quality log10CFU/g of gari is shown in Table 3. The Table shows that the 

TVBC was highest (3.655) in gari from Agoasu district of KA local Government and lowest (3.070) in Ihejiwo in 

Oju locality. The TCC (log10CFU/g) was highest (2.361) in Agoasu district of KA local Government and lowest 

(1.903) isolated from Adaka area of Makurdi Locality. Salmonella and Shigella spp were not isolated. The Table also 

shows EC count to be highest at 1.397 log10CFU/g from samples isolated from KA in KA Local Government Area. 

Some localities had no E. coli whereas Staphylococcus aureus was highest (1.778og10CFU/g) in Tionsha area of 

Makurdi.  

Mean bacterial load (log10CFU/g) of the cassava products irrespective of location is presented in Table 4. The 

Table shows that cassava peels used for animal feeds was the highest values of TVBC (4.456) TCC (3.025) EC 

(1.663) and SA counts. Gari had correspondingly the lowest values of TVBC (3.193) TCC (2.580) EC (not isolated) 

and SA counts. Salmonella sp. and Shigella sp. were not isolated (Table 3) from any of the cassava food product. The 

E. coli counts ranged from not isolated to 1.663 log10 CFU/g. Table 4 also presents the SA counts ranging from 

1.505 log10CFU/g to 1.806 log10 CFU/g. 

 
Table-3. Effect of location on the bacterial quality (log10CFU/g) of gari. 

Local Govt.  Locations TVBC TCC SAL SHI EC SA 

Katsina-Ala Katsina-Ala 3.602 2.146 - - 1.397 1.301 
Agasoma 3.301 2.000 - - 1.079 1.161 
Agoasu 3.653 2.361 - - 1.079 1.342 
Ikyose 3.344 2.079 - - 1.000 1.301 

Makurdi Tionsha 3.778 2.113 - - 1.000 1.778 
Mbahaya 3.544 2.000 - - - 1.000 

Yagba 3.176 2.161 - - 1.176 1.113 
Adaka 3.778 1.903 - - - - 
Mbayo 3.204 2.204 - - - 0.778 

Oju Obolori 3.602 2.113 - - 1.100 1.477 
Ihiejwo 3.070 2.113 - - 1.204 1.402 

Ehurekpe 3.079 2.161 - - - 1.000 
Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = E. coli, SA = S. aureus. 

 
Table-4. Mean bacterial load (log10CFU/g) of the Cassava products irrespective of location. 

Process Products TVBC TCC SAL SHI EC SA 

Cassava peels 4.456 3.025 - - 1.663 1.806 
Cassava chips 4.310 2.623 - - 1.415 1.579 
Fufu 4.334 2.806 - - 1.447 1.643 
Gari 3.193* 2.580 - - - 1.505 

Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = 

Shigella sp. EC = E. coli, SA = S. aureus, * = significant difference along the column. 

 

The influence of the methods of processing on the mean bacterial load (log10CFU/g) of the different cassava 

products is presented in Table 5. Whereas the TVBC values of the traditionally processed cassava peels, cassava 



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chips and gari did not show any statistically significant differences (p<0.05) with the mechanically processed foods, 

traditional processed fufu significantly had higher TVBC value than mechanically processed ones. Comparison 

between the traditionally and mechanically processed cassava products for TCC, the difference for each value did 

not vary significantly. Salmonella and Shigella spp.  were not isolated, whereas the range of E. coli and S. aureus not 

isolated to 1.857 and not isolated to 2. 819 (log10CFU/g) respectively. 
 

Table-5. Influence of the methods of processing on the mean bacterial load (log10CFU/g) of the different Cassava products. 

Processing method Cassava product TVBC TCC SAL SHI EC SA 

Traditional Cassava peels 4.220 3.049 - - 1.681 2.556 
Cassava chips 3.025* 2.681 - - 1.362 2.716 
Fufu 4.158 3.025 - - 1.857 2.819 
Gari 2.833* 2.079* - - - 2.447 

Mechanical Cassava peels 4.107 2.982 - - 1.505 2.362 
Cassava chips 3.009* 2.806 - - 1.415 2.681 
Fufu 3.121 2.991 - - 1.623 2.748 
Gari 2.819* 2.415* - - - - 

Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = E. coli, SA = S. aureus, * = 
significant difference along the column. 

 

The mean bacterial profile (log10CFU/g) of the cassava chips following different drying methods is shown in 

Table 6. The total viable bacterial count was highest in cassava chips dried along the roadside (6.98), followed by 

chips dried at the roofs of houses. Oven-dried cassava chips had the lowest TVBC (2.763). Even though coliform 

was not isolated from cassava chips dried in the oven and at the roof of houses, roadside drying accounted for the 

highest TCC (4.486 log10CFU). Salmonella and Shigella spp. were not isolated from the cassava chips irrespective of 

the drying method. Similar to TVBC and TCC records, roadside drying presented the highest EC and SA isolates. 

 
Table-6. Mean bacterial profile (log10CFU/g) of the cassava chips following different drying methods. 

Drying Method TVBC TCC SAL SHI EC SA 

Concrete slab 5.162 2.806* - - 2.204 2.914 
Mats 5.220 4.025 - - 2.362 2.914 
Oven 2.763* - - - - 1.204* 

Roof of house 4.093** - - - - 1.623* 
Road side 6.968*** 4.486 - - 2.580 3.318 

Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = E. coli, SA = S. 
aureus, * = significant difference along the column. 

 

Table 7 presents the mean bacterial profile (log10CFU/g) of cassava product used in making fufu following 

different drying methods. Total viable bacterial count ranged from 2.826 to 5.982 log10CFU. The highest TVBC 

was recorded in roadside drying followed by drying on concrete slab. The lowest TVBC was recorded oven-dried 

fufu product. Total coliform count was highest (3.623) in samples dried along roadside and lowest (1.301) in oven-

dried fufu samples. In all the parameters assessed, roadside drying gave the highest level of fufu contaminants 

whereas oven-dried fufu presented the least bacterial load, followed by drying at the roof of houses. No Salmonella 

and Shigella spp. were isolated outside roadside drying. The range of E. coli and SA were from not isolated to 2.354 

and from 1.041 to 1.623 log10 CFU/g respectively. 

 
Table-7. Mean bacterial profile (log10CFU/g) of fufu following different drying methods. 

Drying Method TVBC TCC SAL SHI EC SA 

Concrete slab 4.459 2.215 - - 1.690 2.025 
Mats 4.380 2.250 - - 1.415 1.982 
Oven 2.826* 1.301* - - - 1.021* 

Roof of house 3.892 2.361 - - 0.602* 1.041* 
Road side 5.982** 3.623** 1.301 1.00 2.354 1.623 

Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella sp. EC = 

E. coli, SA = S. aureus, * = significant difference along the column. 



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The mean bacterial load (log10CFU/g) of gari samples following the different storage places is as shown in 

Table 8. Total viable bacterial counts and TCC were maximum (4. 350 and 2. 806 log10 CFU/g respectively) when 

the gari was stored in the kitchen and lowest when the storage was in drums (3.982 and 2.380 log10 CFU/g 

respectively). Salmonella and Shigella spp. were not isolated from the stored gari irrespective of the storage type. 

Escherichia coli isolates ranged from not isolated to 1.556 log10 CFU/g. Staphylococcus aureus was highest (1.732 log10 

CFU/g) when the gari was stored in the kitchen and lowest as the gari was stored in drums. 

 
Table-8. Mean bacterial profile (log10CFU/g) of the gari following different storage methods. 

Storage Method TVBC TCC SAL SHI EC SA 

Kitchen 4.350 2.806 - - 1.415 1.732 
Bags 4.107 2.447 - - 1.556 1.556 

Clay pots 4.065 2.748 - - - 1.204 
Baskets 4.158 2.505 - - 1.447 1.681 

Head pans 4.033 2.556 - - - 1.556 
Drums 3.982 2.380 - - - 1.681 

Note: TVBC = Total Viable Bacterial Counts, TCC = Total Coliform Counts, SAL = Salmonella sp. SHI = Shigella 

sp. EC = E. coli, SA = S. aureus, * = significant difference along the column. 

 
Table-9. Cyanide (HCN) concentration (mg/kg) of the different cassava products. 

S/No. Sample Mean Minimum Maximum 

1 Cassava peels 10.75**** 7.00** 14.50** 

2 Cassava chips 5.35*** 2.00* 11.25 
3 Fufu 3.78** 0.75 9.40 
4 Gari 1.70* 0.85 2.25* 

Note: * = significant difference along the column. 

 

The hydrogen cyanide (HCN) content (mg/kg) determined spectrometrically from the different cassava 

products varied amongst themselves Table 9. The mean, minimum and maximum cyanide (HCN) concentration 

(mg/kg) of the different cassava products as presented in Table 9 shows there is a progressive decrease in the 

cyanide contents from cassava peels to cassava chips to fufu and least in gari. The highest hydrogen cyanide content 

(14.50 mg/kg) was recorded in cassava peels whereas gari had the least hydrogen cyanide (2.25 mg/kg). The 

hydrogen cyanide of cassava peels was significantly higher than the load of gari.  

 

4. DISCUSSION 

Bacteriological quality of the different cassava products processed in the study area was not remarkably 

differentiated in the line of location, processing, drying or storage even though numerical differences existed. They 

were differentiated along product lines. The total viable bacterial count is used as a quantitative measure of the level 

of contamination of food. Even though the different products presented varying TVBC, in the present study, the 

TBVC obtained were within the recommended limit since the contamination level were not ≥ 106 CFU/g. Cassava 

products consumed as food and feed are being produced in manners that they are not standardized, bringing queries 

to the quality and safety indices and most importantly hiking public health concerns [13]. Handling of cassava 

products with bare hands, drying on bare cement floors, mats or basins, display on open containers during storage 

and sales, and carriage over a long distance in inappropriate containers and the handling during the process are the 

major route of transmission of bacteria. Long storage could worsen the food and feed value and demand more public 

health concerns. All the above listed were observed during the survey in the present study. 

The mode of storage calls for concern. From the survey done, the cassava processors were not having conscious 

efforts to store the products in a way that microbial multiplication is prevented. The increase in relative humidity 

which is largely responsible for the spoilage of most stored agricultural produce is not put to check. Food safety 

demands food free of pathogens and spoilage organisms. In industrialized nations, efforts are being made to reduce 

if not completely eradicate possible food-borne disease outbreak owing to handling. In developing countries, such 



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handling consciousness is most especially lacking in addition to the non-specialized and non-standardized protocol. 

These are possible routes of contamination [14].   

The study shows the presence of coliforms (TCC) and Escherichia coli (EC) within the range of not debatable to 

4.486 CFU/g and not debatable to 2.580 CFU/g respectively. Coliforms are surrogate organisms used to indicate 

quality in addition to some specific indicators like Escherichia coli. The presence of these organisms could mean 

possible material contact with fecal matter. This is not impossible because of the processing and storage operations 

discussed above. Specific pathogens Salmonella and Shigella spp were almost not found in predominantly all the 

cassava samples assayed. The presence of Staphylococcus aureus in the products is not surprising since the organism 

is a normal flora of a human body. The processors could shed the organism unknowingly to the products. 

All the gari and fufu samples of the present study had hydrogen cyanide contents lower than the recommended 

limit of 10 mg/kg [9, 15]. However, some of the cassava peels and cassava chips had cyanide contents higher than 

the acceptable limit. Consumers of such products are therefore at risk since the toxicity of cyanide to humans even 

at sub-lethal doses has been well established [1].  

The hydrogen cyanide contents of the cassava products of the present study showed significant variation 

amongst products. Nambisan [7] noted that the cyanide content of cassava largely depends on the variety which is 

an intrinsic genetic attribute of the plant. Traditional methods of processing of cassava including boiling, drying, 

parboiling and baking, steaming, frying and preparation to flour reduce cyanide in a range of 25% to 98% [7]. The 

variation could therefore be attributed to either the difference in the varieties or on the processing protocol used. 

Cassava peels and chips are not fermented which could account for the higher cyanide contents. 

 

5. CONCLUSIONS 

The total viable bacterial counts in the cassava products were high but not higher than the recommended 

levels. Salmonella and Shigella spp. were sparingly found in the samples whereas coliform and Escherichia coli 

indicative of poor hygienic status were found. There was a progressive decrease in the cyanide contents from 

cassava peels to cassava chips to fufu and least in gari. The highest hydrogen cyanide concentration of 14.50 mg/kg 

recorded in cassava peels was higher than 10 mg of HCN/kg body weight recommended by WHO and therefore 

poses danger to consumers.  

 

Funding: Authors acknowledge the financial support from the Tertiary Education Trust Fund 
based in Abuja Nigeria and the encouragement from the Vice-Chancellor, Director of Research 
and Mr. Otolo Ogili, all of Federal University of Agriculture, Makurdi. 
Competing Interests: The authors declare that they have no competing interests.  
Acknowledgement: All authors contributed equally to the conception and design of the study. 

 

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