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Nature and Science, 4(3), 2006, Uzeh, et al, Microbiological and Nutritional Qualities of Dairy Products
Microbiological and Nutritional Qualities of Dairy Products: Nono
and Wara
Roseline E. Uzeh *, Regina E. Ohenhen **, Ayodeji K. Rojugbokan *
* Department of Botany and Microbiology, University of Lagos, Nigeria. Telephone: 002348051217750.
Email: roseline_uzeh@yahoo.com
** Department of Microbiology, Ambrose Alli University, Ekpoma, Nigeria. Telephone: 002348033555312.
Email: drginaohen@yahoo.co.uk
ABSTRACT: The microbiological and nutritional qualities of two fermented dairy products: nono and wara were
investigated. Bacteria and fungi were isolated from both products. The bacteria isolated include Acinetobacter
mallei,Alcaligenes faecalis, Bacillus cereus, Enterobacter aerogenes, Enterobacter cloacae, Micrococcus spp,
Serratia spp, Flavobacterium spp, Staphylococcus aureus and Klebsiella licquifasciens. The fungal isolates were
Aspergillus niger, Aspergillus fumigatus, Penicillium chrysogenum, Rhizopus spp, Fusarium moniliforme, and
Trichoderma reesii. The mean total plate count of nono was 3.55x10
8
cfu/ml, while that of wara was 4.55x10
8
cfu/g.
The mean coliform count was 4.25x10
7
cfu/ml for nono and 2.40x10
7
cfu/g for wara. While the mean fungal count
was 12.9x10
6
cfu/ml for nono and 1.31x10
7
cfu/g for wara. The respective moisture content and total titratable acid
were higher in nono (86.03%, 1.37%) than in wara (55.68%, 0.48%). Wara was of a higher pH (4.64), than nono
(2.87). Wara had higher values respectively for fat, ash, and protein (18.55%, 1.5%, and 23%) than nono (3.68%,
0.97%, and 6.40%), while the carbohydrate level was lower in wara (1%) than in nono (2.9%). Nono and in
particular, wara, are of good protein sources. However, the range of microorganisms isolated from both products
pose serious threat to food safety, and the need to ensure the microbiological safety of these products can not be over
emphasized. [Nature and Science. 2006;4(3):37-40].
Keywords: Nono; wara; microbiological and nutritional qualities; food safety
INTRODUCTION
Nono and wara are local dairy products that are
produced and widely consumed in many African
countries, including Nigeria. Mainly the Fulanis
produce milk locally in Nigeria and the excess milk is
processed into these products for preservation (Akinyele
et al., 1999). Nono and wara are produced in homes,
especially in villages where shelf-life and safety of the
products are not considered. They are however sold to
both rural and urban people as food. Nono is produced
from non-pasteurized cow milk collected in a container
called calabash and allowed to ferment naturally for 24
h (Eka and Ohaba, 1977; Olasupo et al., 1996). Wara is
a white soft non-ripened cheese made by the addition of
a plant extract (Calotropis procera) to the non-
pasteurized whole milk from cattle (Adeyemi and Umar,
1994).
Poor hygiene, practiced by handlers of these
products, may lead to introduction of pathogenic
microorganisms into the products and since they do not
undergo further processing before consumption, these
foods may pose risk to their consumers.
This research is aimed at isolating and identifying
microorganisms present in nono and wara in addition to
determining the nutritional and some physicochemical
qualities of nono and wara. These will help to ascertain
the microbial and product quality of nono and wara.
MATERIALS AND METHODS
Collection of samples
Nono samples were purchased from hawkers at
Yaba, Okoko, Idiaraba, Sabo, and Mile 12 markets and
the samples were labeled A, B, C, D, and E
respectively.While wara samples were purchased from
markets in Orile, Oshodi, Mushin, Ketu, and Agege, all
in Lagos state, Nigeria, and the samples were labeled F,
G, H, I, and J respectively.
Determination of the physicochemical parameters of
nono and wara
Moisture content
A clean platinum dish was dried in an oven and
cooled in a desiccator. The cooled dish was weighed.
From the nono sample 5 g was weighed and spread on
the dish, the dish containing the sample was weighed. It
was then transferred into the air oven at 105
0
C to dry for
about 3h. A pair of tongs was used to transfer the dish
into a desiccator, allowed to cool and weighed. The dish
was returned into the oven for 30 min and again cooled
in a desiccator and weighed (AOAC, 1980).The process
37
Nature and Science, 4(3), 2006, Uzeh, et al, Microbiological and Nutritional Qualities of Dairy Products
was repeated until a constant weight was obtained. This
was done for other samples.
Hydrogen ion concentration (pH)
In order to obtain the pH of the samples, 5 g each
was weighed and suspended in 10 ml of distilled water.
The pH was determined with a pH meter.
Nutritional analysis
The carbohydrate was determined according to
Anthrone reaction method (Southgate, 1976). Protein
was analyzed for by the Microkjedhal estimation of
nitrogen, using a conversion factor of %N x 6.25.
Determination of the ash content was done according to
AOAC (1980) method, while that of fat was done as
described by Pearson (1976).
Determination of crude fiber
The nono and wara samples to be analyzed were
defatted using petroleum ether. From the defatted
sample 1 g was weighed into 500 ml beaker containing
100 ml of trichloroacetic acid. The content of the beaker
was boiled and refluxed for 4 min. It was cooled and
filtered with filter paper (Whatman No.1). The residues
were washed six times in hot distilled water and once
with mentholated spirit. The filter paper together with
the sample was transferred into a porcelain crucible and
dried in an oven overnight at 100
0
C, after which it was
cooled in a desiccator, weighed, ashed in a muffle
furnace at 600
0
C for 4h and weighed again after
cooling. The loss in weight during incineration was
equivalent to the amount of crude fiber.
Microbiological analysis
This was done both quantitatively and qualitatively.
Samples were diluted serially using sterile distilled
water as diluent. From appropriate dilutions 1ml each
was plated in duplicate using the pour plate method.
Media used include nutrient agar, MacConkey agar, and
potato dextrose agar. The nutrient and MacConkey agar
plates were incubated at 37
0
C for 24 h, while the potato
dextrose agar plates were incubated at 25
0
C for 48-72 h.
After incubation, developed colonies were counted, and
representative colonies were sub cultured to obtain pure
cultures of isolates.
Identification of microbial isolates
Identification of the bacterial isolates was based on
cultural, morphological, and biochemical characteristics
following standard methods (Buchanan and Gibbons,
1974) while that of fungi was also based on cultural and
morphological characteristics and standard methods
were followed (Talbot, 1971; Bryce, 1992).
RESULTS
The moisture and total titratable acid were higher in
nono than in wara, and the pH of wara was higher than
that of nono (Table 1). From the nutritional analysis,
wara had higher values for fat, ash and protein than
nono. Carbohydrate was however more in nono than in
wara. Crude fiber was not detected in both products
(Table 2).
The mean total plate count of nono was 3.55x10
8
cfu/ml while that of wara was 4.55x10
8
cfu/g. The mean
coliform count was 4.25x10
7
cfu/ml for nono and
2.40x10
7
cfu/g for wara. While the mean fungal count
was 12.9x10
6
cfu/ml for nono and 1.31x10
7
cfu/g for
wara (Tables 3a and 3b). The bacteria isolated from the
products were Acinetobacter mallei, Alcaligenes
faecalis, Bacillus cereus, Enterobacter aerogenes,
Enterobacter cloacae, Micrococcus spp, Serratia spp,
Flavobacterium spp, Staphylococcus aureus, and
Klebsiella licquifasciens (Table 4). The fungal isolates
include Aspergillus niger, Penicillium chrysogenum,
Rhizopus spp, Fusarium moniliforme, Trichoderma
reesii, and Aspergillus fumigatus.
Table 1. Physicochemical parameters of nono and wara
Parameters Nono Wara
Moisture (%) 86.03 55.68
Total titratable acid (%) 1.37 0.48
pH 2.87 4.64
Table 2. Nutritional content of nono and wara
Parameters ( % ) Nono Wara
Fat 3.68 18.55
Ash 0.97 1.50
Crude fiber not detected not detected
Protein 6.40 23.00
Carbohydrate 2.90 1.00
Table 3a. Microbial count of nono
38
Nature and Science, 4(3), 2006, Uzeh, et al, Microbiological and Nutritional Qualities of Dairy Products
Locations Total plate count Coliform count Fungal count
(x 10
8
cfu/ml) (x 10
7
cfu/ml) (x 10
6
cfu/ml)
A 2.65 3.80 9.5
B 1.75 2.10 5.0
C 2.25 5.20 8.5
D 1.80 4.10 18.5
E 9.30 6.00 23.5
Mean 3.55 4.25 12.9
Table 3b. Microbial count of wara
Locations Total plate count Coliform count Fungal count
(x 10
8
cfu/g) (x 10
7
cfu/g) (x 10
7
cfu/g)
F 1.50 1.55 1.00
G 10.90 2.65 1.15
H 3.90 2.40 1.90
I 3.50 3.20 1.35
J 3.70 2.20 1.15
Mean 4.55 2.40 1.31
Table 4. Bacteria isolated from nono and wara
Bacterial isolates Nono Wara
Acinetobacter mallei - +
Alcaligenes faecalis - +
Bacillus cereus + +
Enterobacter aerogenes + -
Enterobacter cloacae - +
Micrococcus spp + +
Serratia spp - +
Flavobacterium spp + -
Staphylococcus aureus + +
Klebsiella licquifasciens - +
Key: + = Present; - = Absent
DISCUSSION
The nutritional content of nono and wara shows
that they are of appreciable nutritional status especially
in the protein content. The dairy products particularly
wara are good sources of protein. Higher protein content
was observed in wara than in nono. This could be due to
accumulation of the protein through expulsion of the
whey, which does not occur in nono production.
The results obtained from the microbial analysis of
nono and wara show that both products were
contaminated with microorganisms of public health
concern. The high total bacterial and coliform count in
both products may be a consequence of the low level of
hygiene maintained during the processing and sale of
the products. This includes the handlers, quality of
water used and the utensils. During the sale of wara,
dirty hands and spoons are dipped into the bowl for
product selection by both hawkers and consumers. The
exposure of both wara and nono while they are
displayed for sale in bowls can serve as source of
contamination. The detection of Enterobacter
aerogenes, Enterobacter cloacae, Klebsiella, and
Serratia species in nono and wara as the case may be,
indicates possible faecal contamination. Being enteric
bacteria, their presence indicates poor hygienic practices
among handlers of nono and wara. Due to the
significance of the faecal-oral route transmission for
many bacterial food-borne diseases, basic hygiene
measures assume a decisive importance in food safety
management (Untermann, 1998).
Other bacteria isolated include Acinetobacter,
Alcaligenes, Flavobacterium, Micrococcus species, and
Staphylococcus aureus. Alcaligenes and
Flavobacterium have been implicated in the spoilage of
milk and its products at even refrigerator temperatures.
Acinetobacter species are known to cause ropiness of
milk and secretion of extracellular enzymes both at
psychrophilic and mesophilic temperatures (Gilmour
and Rowe, 1990).
Bacillus cereus which is known to be highly
resistant to environmental stress due to its sporing
39
Nature and Science, 4(3), 2006, Uzeh, et al, Microbiological and Nutritional Qualities of Dairy Products
nature was also isolated, and B.cereus is known to be of
public health importance since it is pathogenic. The
detection of Staphylococcus aureus is also of public
health importance because of its ability to cause a wide
range of infections especially food-borne intoxication.
This organism was equally isolated by Olasupo et al. (
2002 ) from wara and kunun-zaki, a cereal based, non-
alcoholic beverage.
The fungal isolates: Aspergillus, Penicillium,
Rhizopus, Fusarium, and Trichoderma species which
were isolated are known spore formers, which therefore
means that they can easily contaminate the dairy
products which are usually exposed during processing,
storage, and hawking. They are major spoilage
organisms of carbohydrate foods (Rhodes and Fletcher,
1966). However, their growth can result in the
production and accumulation of mycotoxins which are
of public health and economic importance.
Microbiological standards have not been put in
place for the two locally processed dairy products: nono
and wara in Nigeria, and even in most African countries
where they are consumed. This is also applicable to
many other locally processed foods in Nigeria. The
isolation of coliforms and some other food pathogens
from these dairy products pose serious threat to food
safety, especially locally processed foods in Nigeria.
Due to the fact that nono and wara are ready-to –eat
foods which are consumed without further processing,
great attention should therefore be given to the
microbiological safety of these products because their
direct consumption may cause health hazard to the
consumers.
Correspondence to:
Roseline E. Uzeh
Department of Botany and Microbiology
Universty of Lagos
Akoka, Lagos, Nigeria
Telephone: +234-805-121-7750
E-mail: roseline_uzeh@yahoo.com
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