Groundnut (Arachis hypogaea L.) is an economically important crop grown in many parts of the world including Nigeria. However, there is paucity information with regards to the mycological quality of groundnut products across the state. The fungal population identified to be associated with groundnut products in three Agricultural zones of Sokoto state were isolated and characterized using standard mycological techniques. Total fungal count (TFC) ranged from 1.2 × 103 to 4.7 × 104 CFU/g with groundnut cake from Sokoto being the most contaminated (4.7×104). Aspergillus flavus was found to be the most frequently isolated fungal species with 28.1% followed by A. niger (20.8%) and A. fumigatus (15.4%). The lessfrequentlyencountered were species of Penicillium notatum (1.4%). The findings from this study suggest that groundnut products obtained from two Agricultural zones are substantially contaminated by fungi responsible for producing Aflatoxin and Ochratoxin which could be unsafe as food or feed ingredients. It was recommended to store groundnut with very low moisture content, evolve other means of processing and use of varieties resistant to fungi and encourage food quality control agencies to take up their responsibilities.

1. Mycological Quality Assessment of Groundnut Products Commonly Consumed in Sokoto State, Nigeria
WJM
Mycological Quality Assessment of Groundnut Products
Commonly Consumed in Sokoto State, Nigeria
*1Salau IA, 2Shehu K, 3Kasarawa AB
*1
Department of Biology, Shehu Shagari College of Education, Sokoto Nigeria
2Department of Biology, Federal University, Birnin-Kebbi, Kebbi State Nigeria
3Department of Science Laboratory Technology, Umaru Ali Shinkafi Polytechnic, Sokoto Nigeria
Groundnut (Arachis hypogaea L.) is an economically important crop grown in many parts of the
world including Nigeria. However, there is paucity information with regards to the mycological
quality of groundnut products across the state. The fungal population identified to be associated
with groundnut products in three Agricultural zones of Sokoto state were isolated and
characterized using standard mycological techniques. Total fungal count (TFC) ranged from 1.2
× 103
to 4.7 × 104
CFU/g with groundnut cake from Sokoto being the most contaminated (4.7×104
).
Aspergillus flavus was found to be the most frequently isolated fungal species with 28.1%
followed by A. niger (20.8%) and A. fumigatus (15.4%). The lessfrequentlyencountered were
species of Penicillium notatum (1.4%). The findings from this study suggest that groundnut
products obtained from two Agricultural zones are substantially contaminated by fungi
responsible for producing Aflatoxin and Ochratoxin which could be unsafe as food or feed
ingredients. It was recommended to store groundnut with very low moisture content, evolve other
means of processing and use of varieties resistant to fungi and encourage food quality control
agencies to take up their responsibilities.
KEY WORDS: Groundnut, Fungi, Quality Assessment, Contamination and Sokoto.
INTRODUCTION
Groundnut production and trade is faced with numerous
challenges and one of the major constraint reported by
Mutegi et al. (2009), Soler et al. (2010) and Chang et al.
(2013) was fungal invasion especially by mycotoxin
producing fungi leading to loss of quality and market value
of the agricultural products. In Nigeria, Groundnut is
traditionally consumed in its boiled, roasted or other
processed form to improve its aroma, flavour and texture.
Fungi are ubiquitous and can infect groundnut at all levels
from production to processing and the supply chains
(Murphy et al., 2006). A significant level of groundnut-
mould infection occurs in the field being encouraged by
damp conditions at the time of harvest, insect infestations,
delayed harvesting as well as improper post-harvest
handling, transporting, drying, storage system and
processing methods (Reddy et al.,2013; Tiffany, 2013).
Mold growth can results in reduced crop yields and
counterproductive reduced livestock productivity.
Mycotoxins are toxins produced by fungi belonging to the
genus Aspergillus. They are typically highly resistant and
they can be a hurdle to international trade, with increased
regulation of foods and feeds and market removal of
commodities not meeting regulatory limits.
*Corresponding author: Ibrahim A. Salau, Department of
Biology, Shehu Shagari College of Education, Sokoto,
Nigeria. Email: ibrahimasalau@gmail.com Tel:
+234(0)8053569551
World Journal of Microbiology
Vol. 3(2), pp. 115-119, September, 2017. © www.premierpublishers.org. ISSN: XXXX-XXXX
Research Article

2. Mycological Quality Assessment of Groundnut Products Commonly Consumed in Sokoto State, Nigeria
Salau et al. 116
The effects of their toxic secondary metabolites, when
contaminating foods in sufficiently high levels, range from
acute to chronic, mutagenic, and teratogenic. Symptoms
of mycotoxicoses range from skin irritation to
immunosuppression, birth defects, neurotoxicity, and
death (ICMSF, 1996).
The death of some children who consumed mouldy
Groundnut cake in Ibadan was linked to fungi (Ikeorah and
Okoye, 2005). Such fungi are also gaining credibility as
sources of health hazards in houses. Furthermore, in the
current state of world concerns with bio safety and
bioterrorism, the use of mycology as weapons cannot be
ignored possibly in relation to food and/or water supplies.
Indeed, the unambiguous identification of fungi remains
the most critical area of mycological taxonomic research
because of the importance of mycology and the somewhat
confused state of the systematics (Salau et al., 2017a).
In essence, this research aims at evaluating groundnut
products samples obtained from various markets across
the three Agricultural zones in Sokoto state for mycological
contamination. This will help to determine the fungal load
of fungicontaminating groundnut products in three
Agricultural zones of Sokoto State Assessing the quality of
the products and possible public health risks posed by the
consumption of these products.
MATERIALS AND METHODS
Study Area
The study was conducted in Sokoto State, which is located
in the extreme North-western part of Nigeria. The State
geographically lies along longitude 11o 301 to 13o 501 East
and latitudes 4o to 61 North and covers a total land mass
of 26,648.48 square kilometres. Sokoto State shares
boundary with Kebbi State to the south, Zamfara State to
the east and the Republic of Niger to the north. The State
has an estimated population of about 4,742,459 people as
of 2015 with 95.9 persons per square kilometre, and 3%
growth rate annually based on 2006 population census
(NPC, 2007). Occupation of city inhabitants includes
farming, trading, commerce, with a reasonable proportion
of the population working in private and public sectors
(MOI, 2008). The soil is predominantly ferruginous tropical
type, texturally sandy and pH of the soil ranges between 6
and 7. Rainfall starts late in June and ends early, in
September but, sometimes extend to October. The
average annual rainfall is between 550 - 1300 mm with
peak in the month of August and a relative humidity of less
than 20%. The highest temperatures of 45°C during the
hot season are experienced in the months of March and
April. Harmattan, (a dry cold and dusty) condition is
experienced between the months of November and
February (Salauetal., 2016b). Modern Sokoto city is a
major commercial centre in leather crafts and agricultural
products (MOI, 2008). There are 23 local government
councils (LGC) in the State with Sokoto as the capital. The
state is divided into four (4) agricultural zones namely,
Sokoto, Gwadabawa, Isa and Tambuwal.
Collection of Samples
A total of one hundred and eighty-nine (189) samples of
Groundnut products were obtained from markets and
stores. The samples (63 each) which included groundnut
kernels, cake (kulikuli) and oil were collected at different
selling shades, stores and centres respectively. Twenty-
one (21) samples were collected from each Agricultural
zone, approximately 200g representative sample was
collected in small polyethylene packs in accordance with
Whitaker techniques (2003).
Fungal culture and isolation
The isolation of fungi was carried out using agar dilution
method as described by Pitt et al., 1992 and Salau et al.,
2017b. Ten (10) grams from each groundnut kernel and
cake powder sample were homogenized with 90 ml of
buffer peptone water and serial decimal dilutions (10-1 to
10-4) were performed. Suspected samples of fungi were
cultured onto the Potato dextrose agar. The medium was
poured into sterile Petri dish and 0.1 ml of each sample
suspension was spread-plated onto the PDA media. The
plates were incubated for 5 to 7 days at 25°C. Identification
of fungal Genera and the determination of each species of
fungi were done using the keys of Klich (2002) for
Aspergillus spp. and Pitt and Hocking (1997) for
Penicillium sp. This was done by observing both
microscopic characteristics and morphology of the
colonies on PDA and SDA medium. The total fungal count
for each plate was expressed as colony-forming units per
gram of sample (CFU/g). Each genus or specie identified
was then expressed as percentage (%) of the total isolated
fungi.
The total colonies of fungi were enumerated and results
were reported in mean and average fungal counts as
described by Pitt and Hocking, (1997) and Dachoupakan
et al. (2009)
Data Analysis
The SPSS 21.0 (Windows version, IL, USA) was used for
data analysis. One-way ANOVA test was used for
comparison of means of TFC across Groundnut products
and overall (%) for fungal species. The means were
separated for test of significance by the Duncan’s Multiple
Range Test.
RESULTS
All groundnut product samples analyzed in this study had
fungal contamination at varying levels. A total of 355 fungal

3. Mycological Quality Assessment of Groundnut Products Commonly Consumed in Sokoto State, Nigeria
World J. Microbiol. 117
Table 1: Distribution of fungi contaminating Groundnut productsin three (3) Agricultural zones of Sokoto state, Nigeria
Percentage (%) of fungal species occurring in Groundnut products samples
Products Zone *TFC
(cfu/g)
Aspergillus
flavus
Aspergillus
niger
Aspergillus
fumigates
Fusarium
solani
Aspergillus
parasiticum
Penicillium
notatum
Rhizopus
stolonifer
Mucur
racemosus
Groundnut
Kernel
Sokoto 2.6×104
23.0 14.8 14.8 13.1 9.8 ----- 14.8 11.5
Isa 1.7×103
19.7 19.7 13.1 4.9 13.1 ---- 3.3 9.8
Tambuwal 2.8×104
26.2 18.0 14.8 18.0 6.6 ----- 18.0 16.4
Mean 2.1×104
Groundnut
cakes
Sokoto 4.7×104
36.9 28.2 23.1 5.1 ---- ---- 5.1 2.6
Isa 1.5×104
31.0 14.3 16.6 12.0 ---- 7.1 14.3 4.8
Tambuwal 3.8×104
34.4 25.0 12.5 9.4 ---- 6.3 12.5 ----
Mean 3.2×104
Groundnut
oil
Sokoto 1.2×103
40.0 26.7 33.3 ---- ---- ---- ---- ----
Isa 1.2×103
27.8 33.3 ---- ---- ---- ---- ---- 38.9
Tambuwal 1.3×103
37.5 29.2 16.7 ---- ---- ---- ---- 16.7
Mean 1.2×103
Overall (%) 28.1a
20.8b
15.4bc
9.0c
5.1c
1.4d
9.8c
10.4c
*TFC (cfu/g): Total fungal count in colony forming units per gram
Overall (%). Mean with different letters in the same row are statistically different (p < 0.05) according to Duncan’s test.
isolates belonging to 8 identified species (Aspergillus
niger, A. flavus, A. fumigatus, Fusarium, Penicillium,
Rhizopus Curvaleria and Mucur) were recovered from the
analyzed samples. Groundnut kernel samples from
Tambuwal zone had the highest total fungal count of
2.8×104cfu/g while those from Isa zone had the least
fungal load, 1.7×103 cfu/g (Table 1). The mean fungal load
of groundnut cake samples from Sokoto zone
(4.7×104cfu/g) was higher than those in other Agricultural
Zones, groundnut oil fungal load was higher in Tambuwal
zone (1.3×103cfu/g) than others with 1.3×103cfu/g both of
them, although there was no significant (P>0.05)
difference in the fungal loads across all Agricultural Zones.
Aspergillus species were recovered from samples in all
locations and account for 64.3% while Fusarium species
were isolated from samples except groundnut oil samples
and at all locations. Penicillium species were present in
only groundnut cake samples from all zones except in
Sokoto. While Rhizopus species occurred only in
groundnut kernel and cakes samples from all zones.
Curvaleria was present in groundnut kernel samples, on
the overall, the incidence of Aspergillus flavus was high
(28.17%) being significantly (P<0.05) much higher than the
proportion of all other fungal isolates. Penicillium species
were the least encountered (1.4%) although its incidence
was significantly (P<0.05) different than the incidence of
Rhizopus and curvaleria lunata. The results are presented
in Table 1.
DISCUSSION
The population and type of fungi recovered from the
groundnut product samples in this study was an insight to
serious public health hazard since some of the species are
notable toxin producers while others were saprophytes;
inciting deterioration of the food material in their bid to
adapt and survive in the microenvironment. The species of
Aspergillus, Rhizopus and Penicillium isolated from
groundnut products samples corroborate to the findings of
Adebesin et al. (2001) who reported similar fungi as
contaminants of Groundnut cake alongside others which
were not recovered or could not be identify in this study.
Gachomo et al. (2004) Jimoh and Kolapo (2008) reported
these fungi together with Fusarium to be the major
contaminating fungi of groundnut in storage. Therefore,
their occurrence in this food product might have originated
from the raw groundnut used in the individual groundnut
cake processing as well as the postproduction exposure of
this marketed snacks to fungal spore resident in the air.
The earlier may be a minor contributor as compared to the
latter (exposure of snacks in markets to air-borne fungal
spores) since the fungal count was higher in markets
located in the Tambuwal Agricultural Zone than Sokoto
and Isa zones locations in the state.
The presence of Aspergillus species such as A. flavus and
A. niger, Fusarium species, Penicillium species and
Rhizopus in the Groundnut cake samples is inconsonance
to the findings of many researchers including Akano and
Atanda, 1990; Jimoh and Kolapo, 2008; Makun et al.,
2010; Salau et al., 2017a), and further concluded that such
isolates may pose a toxicological threat to the consumers
since majority of the isolates of these fungal species are
toxigenic. Rhizopus is known to liberate a metabolite
rhizonin A (Wilson et al., 1984) while aflatoxins,
ochratoxins, fumonisins, trichothecenes, citrinin and
patulin are well produced during metabolism by the above
mentioned fungi. Akano and Atanda(1990) reported the
presence of fungi and aflatoxins in Groundnut cake from
Ibadan, Oyo state, Nigeria after the incidence of deaths
resulting from consumption of aflatoxin-contaminated
foods in Nigeria.
Stored groundnuts represent a complex ecosystem in
which seed spoilage by fungi is determined by a range of
factors which can be classified into four groups; intrinsic
nutritional factors, and extrinsic, processing and implicit
factors (Magan et al., 2004). Alone or in combination
among them, these factors affect the composition of the
fungal population, inducing changes throughout the
storage period. The recovery of propagules of fungal
species in all groundnut samples and the significantly
higher incidence of A. flavus species compared to other

4. Mycological Quality Assessment of Groundnut Products Commonly Consumed in Sokoto State, Nigeria
Salau et al. 118
isolates, irrespective of processing method used, supports
previous studies showed that groundnut is highly
susceptible to contamination from Aspergillus species
(Soler et al., 2010; Sultan and Magan 2010;
Nyirahakizimana et al., 2013). The recovery of three
species of Aspergillus species, from the samples in this
study, agrees well with the findings of Salau et al. (2017b).
CONCLUSION
This study recovered high incidence of mycological
contamination by species of A. niger and A. flavus (66.7%)
in three Groundnut products of three Agricultural zones in
Sokoto state, Nigeria. The findings in this research
suggested that groundnut products could be contaminated
with high levels fungi (A. niger and A.flavus), which were
suspected of Aflatoxin, ochratoxin A and other mycotoxins
producing fungal species thereby making several products
of groundnut samples unsafe for human consumption and
as animal feeds ingredients for feed formulation. The
contamination of groundnut products value chain by mold
is closely related to agricultural practices in the state such
as the use of fungicide, organic manuring and un-removal
of groundnut kernel (sorting) contaminated with mold
before harvest, poor handling, storage and processing
methods after harvest among others.
Based on these findings in this study, it was recommended
that:
There is the need to enhance awareness among farmers,
processors, sellers and consumers to develop strong and
appropriate protocols for proper handling of groundnut
products from production to storage sites and to ensure
safety ofthe products for both humans and animals
consumption.
REFERENCES
Adebesin AA, Saromi OT, Amusa NA, Fagade SO (2001)
Microbiological quality of some Groundnut products
hawked in Bauchi, a Nigerian City. J. Food Technol. Afr.
6 (2):53-55.
Akano DA. and Atanda OO. (1990) The present Level of
Aflatoxin in Nigeria Groundnut Cake (‘Kulikuli’). Letters
in App. Microbiol. 10: 187-18.
Atanda SA., Pessu PO., Aina JA., Agoda S., Adekalu OA.,
and Ihionu GC. (2013) Mycotoxin Management in
Agriculture. Greener J. of Agric. Sci.; 3 (2); 176-184.
Bankole SA. OgunsanwoBM. and Eseigbe DA. (2005)
Aflatoxins in Nigerian dry-roasted Groundnuts Food
Chem89:503–506.
Chang AS, Sreedharan A, Schneider KR. (2013) Peanut
and peanut products: a food safety perspective. Food
Contr32:296–303.
Dachoupakan C., Ratomahenina MR., Guiraud JP.,
Baccou, JC. and Schorr GS. (2009). Study of the
phenotypic and genotypic biodiversity of potentially
ochratoxigenic black aspergilli isolated from grapes.
International Journal of Food Microbiology, 132,14-23.
http://dx.doi.org/10.1016/j.ijfoodmicro.2009.03.011
Gachomo EW, Mutitu EW, Kotchoni OS. (2004) Diversity
of fungal species associated with peanuts in storage and
the levels of aflatoxins in infected samples. International
J. of Agric. Biology;6(6): 955–959.
ICMSF, (1998). Microbial ecology of food commodities.
Academics and Professional, 615p.
Jimoh KO, Kolapo AL. (2008) Mycoflora and Aflatoxin
production in market samples of some selected Nigerian
foodstuffs. Res. J. of Microbiology3: 169–174.
Klich MA. (2002). Introduction; economic and medical
importance of Aspergillus. In Identification of common
Aspergillus species (pp. 1-16).
Makun HA, Anjorin ST, Moronfoye B, Adejo FO, Afolabi
OA, Fagbayibo G, Balogun BO, Surajudeen AA. (2010)
Fungal and Aflatoxin contamination of some human food
commodities in Nigeria. African Journal of Food Science;
4(4): 127–135.
Murphy PA, Hendrich S, Landgren C and Bryant CM.
(2006) Food mycotoxins, an update. J. of Food Sci.;
71(5): 51–65.
Mutegi CK, Hendrisks SL., Jones RB, Okello JJ, and Ngugi
H.K. (2007). Role of collective action and handling
practices on aflatoxin contamination of groundnuts:
Evidence from Kenya. African Crop Science Conference
Proceeding, 8: 1779 – 1782.
National Population Commission (NPC, 2007). Population
Census Data, Nigeria, Federal Republic of Nigeria
Official Gazette, National and State Provisional Total
Census, Printed and Published in Federal Government
Printer, Lagos, No 21 vol.94,
Nyirahakizimana H, Mwamburi L, Wakhisi J, Mutegi CK,
Christie ME, Wagacha JM. (2013) Occurrence of
Aspergillus spp. and Aflatoxin contamination in raw and
roasted Groundnuts from formal and informal markets in
Eldoret and Kericho towns, Kenya. Adv.Microbiol.3:333–
342.
Pitt J. and Hocking A. (1997). Fungi and Spoilage (2nd
ed.). London, N.Y. Blackie Academy and Professional
Pittet A, (1998). Natural occurrence of mycotoxins in foods
and feeds: an updated review. Revue Medicine
Veterinary149: 479 – 492.
Reddy CR, Reddy AR, Waliyar F, Alur AS, Gowda CLL,
Reddy BVS and Rao PP (2013). Mycotoxins in sorghum
and pearl millet: effect on human and animal health and
their management. CFC/FAO Paper Pp 1.
Salau IA, Shehu K, Muhammad S and Umar RA (2016a)A
Survey of Aflatoxin Contamination of Fermented Milk
(Nono) Sold in Sokoto State, Nigeria. Proceedings of the
2nd Annual International Conference Faculty of Science
Northwest University, Kano Pp. 632-637
Salau IA, Shehu K, Muhammad S.and Umar RA (2016b).
Aflatoxin Contamination of Stored Groundnut Kernel in
Sokoto State, Nigeria. Greener Journal of Agricultural
Sciences. Vol. 6 (10), pp. 285-293, November 2016.
(DOI: http://doi.org/10.15580/GJAS.2016.10.092316144)

5. Mycological Quality Assessment of Groundnut Products Commonly Consumed in Sokoto State, Nigeria
World J. Microbiol. 119
Salau IA, Shehu K, Muhammad S, and Umar RA. (2017a).
Determination of Aflatoxin levels in groundnut oils
marketed in Sokoto State, Nigeria. International
Research Journal of Biochemistry and Biotechnology,
3(1): 051-054.
SalauIA. Shehu K. and Farouq AA. (2017b). Molecular
Characterization of Mycotoxin producing Fungi
Contaminating Groundnut Products In Sokoto State,
Nigeria. J. of Computation in Biosciences and
Engineering. 3(4) 1-4 DOI: 10.15297/JCLS.V3I4.01
Singh K, Frisvad JC, Thrane U, Mathu SB, (1991). An
illustrated manual on identification of some seed borne
Aspergilli, Fusaria, Penicillia and their mycotoxins. Heller
up, Denmark: Danish Government, Institute of seed
pathology for developing countries. 133 p.
Soler CMT, Hoogenboom OR, Diarra B, Waliyar F, Traore
S. (2010) Groundnut contamination by Aspergillus flavus
and Aflatoxin B1 in granaries of villages and markets of
Mali, West Africa. J. of Food Agric Environ8:195–203.
Sultan Y and Magan N, (2010). Mycotoxigenic fungi in
peanuts from different geographic regions of Egypt.
Mycotoxin Research26: 133–140.
Tiffany I (2013). The implication of aflatoxin contamination
for local food safety in Senegal.
www.hungercenter.wpengine.netdna-cdn.com
Whitaker TB. (2003) Standardisation of mycotoxin
sampling procedure an urgent necessity. Food
Contr14:233–237.
Wilson T, Rabie CJ, Fincham JE, Steyn PS and Schipper
MA. (1984) Toxicity of rhizonin A, isolated from Rhizopus
microspores, in laboratory animals. Food and Chemical
Toxicology 22(4): 275–281.
Accepted 11 August 2017
Citation: Salau IA, Shehu K, Kasarawa AB (2017).
Mycological Quality Assessment of Groundnut Products
Commonly Consumed in Sokoto State, Nigeria. World
Journal of Microbiology, 3(2): 115-119.
Copyright: © 2017 Salau et al. This is an open-access
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