The Journal of Food Technology in Africa, Vol. 6, No. 3, July-Sept, 2001 pp. 87-89
Microbiological quality of locally fermented milk (nono) and fermented milk-cereal mixture (fura da nono) drink in Bauchi, a Nigerian city
1A. A. Adebesin, 2N. A. Amusa*, and 3S. O. Fagade
1Department of Science Laboratory Technology, Federal Polytechnic,
Ede. Osun State.
Code Number: ft01023
Fura da nono, fura and nono samples obtained from three areas in Bauchi metropolis were analysed to determine their microbial quality, the moisture content, pH and titratable acidity. The analysed samples were found contaminated with coliforms. The identified bacterial isolates from the products were Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Enterobacter sp, Streptococcus sp, Bacilus cereus and Lactobacillus sp. The fungal isolate includes yeast Sacharomyces cerevisae and mold species of Aspergillus flavus and Rhizopus nigricans. The average microbial load of bacteria isolates from the samples ranges between 3.0 -4.7 x 104 cfu/ml., for fungal isolates it ranges between 1.0x104 to 2.9x104 cfu/ml and yeast counts from 0.0 x104 cfu/ml in fura to 5.3 x104 cfu/ml in fura da nono.
Key words: Microbiological quality, nono, fura da nono, mold
"Fura da nono" (fermented milk-cereal mix) is a highly nutritious beverage which is a two-in-one product, consisting of a cereal, 'Fura', made from millet and 'nono' a fermented milk product similar to yoghurt. Fura da nono is sold from calabash converted with mat using scopes made from calabash. In the market, Fura is mixed with nono in a bowl for customers. Usually one bowl is used in mixing for all the customers, without cleaning. Depending on the consistency, the product is used as food, refreshing drink and a weaning food for infants. The product is in high demand, especially in the months of November to July (Umoh, et al 1988).
The poor handling of fura da nono during processing and marketing exposes it to microbial contamination. Fura is usually molded into balls by hand during its production, and the hands of the producers could be a source of contamination. Houseflies are always found in large numbers at the production sites and at sale outlets.
Shehu and Adesiyuh (1990) reported that in order to increase the volume and improve colour of nono, the female hawkers, prior to sale, engage in the fraudulent act of adding stream water and a milky white supernant of water-soaked baobab tree seeds. This act could further lead to the contamination and spoilage of this product.
Umoh, et al (1988) isolated Straphyococcus sp from Fura da nono while Shehu and Adesiyun (1990) isolated Escherichia coli from Fura da nono. Their reports indicate the possibility of these products serving as source of microbial food poisoning. Fura da nono offered for sale is usually poorly handled and presented to consumers mostly in unhygienic manner. This research was therefore designed to isolate and identify microorganisms associated with fura da nono, fura and nono sold in Bauchi metropolis in 1998 and 1999 with a view of giving possible suggestions to improving the quality of the product.
Materials and Methods
Samples on nono, fura balls and fura da nono were purchased from three areas of Bauchi town, Viz Yelwa, Wunti and Gwallameji. Nono and fura da nono samples were collected in sterile large screw capped bottles while fura balls were kept in new sterile polyethylene bags. Four samples each of the products were purchased from the local Fulani's bimonthly from each area between Nov. 1997 and Feb 1998 and repeated in 1999.
Isolation of Isolates
Ten-fold dilutions of each of the samples were made using peptone water. Appropriate dilutions were made and 0.1 ml of the diluted samples were pour plated in triplicate plates on Plate Count Agar (PCA) for viable count, Eosin Methylene Blue (EMB) for Escherichia coli count, Mannitol Slat Agar (MSA) for Staphylococcal count and Brilliant Green Bile Broth (BGBB) for coliform test. Sabourand Dextrose Agar with Chloramphenicol (250mg/100ml) was used for fungi, while for yeast count the medium was adjusted to pH 3.5 with tartaric acid. All plates were incubated for 48 hours at 30°C except for Sabourand Dextrose Agar that were incubated at 26°C for 6 days. Colonial counts were made using digital illuminated colony counter (Gallen kamp model).
Pure cultures of each isolate were obtained by streaking the specific colonies on suitable media and incubated appropriately, these were maintained in an agar slants in McCarthney bottles.
Identification of microbial isolates
The identification of the bacteria colonies was based on classification schemes proposed by Harrigan and McCance (1976), Buchanan and Gibbons (1974) and Collins and Lyne, (1984). The identification was based essentially on morphology and biochemical reactions.
The associated fungi were then identified with reference to Frazier and Westhoff (1978), while the yeast were identified using the methods of Beech et al (1968) and Lodder, (1970). The identity of the microbes were further confirmed by comparison with the existing cultures already identified by the International Mycological Institute, Kew, London, obtained from the Seed Health Laboratory, International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria.
The pH of the samples were determined using a pH meter (Titrimeter U9N model). The moisture content and titratable acidity were determined as described by Egan et. al. (1981).
Results and Discussion
The bacterial found associated with fura, nono and fura da nono includes Escherichia coli, M. luteus, Streptococcus sp, Staphylococcus aureus, B. cereus, Lactobacillus sp and Enterobacter sp (Table 1) Results of this experiment indicate the presence of S aureus, B cereus, Streptococcus sp and E. coli which have previously been implicated in food poisoning outbreak of some products (Frasier and Westhoff, 1978). The presence of E. coli and Enterobacter species in the samples also indicates that they are likely to contain other enterobacteriaceae, as the presence of E. coli in foods is an indication of faecal contamination of products. However, Lactobacillus sp. is a lactic acid bacterium probably involved in fermentation of the product. Zaika et al., (1983) reported Lactobacillus plantarum as an hetero-fermentative lactic acid bacterium, found to be important in initiating fermentation of vegetables and fruit juices.
The fungi isolate also includes R. nigricans, A. flavus a yeast S. cerevisae (Table 1). The presence of A flavus, in the product might probably make its consumption harzadous to health. Some strains of A. flavus produces Aflatoxin, a potent toxin that has been implicated in Hepatoxin and Cancer in mammals including man (Bothast, 1978; Frazier and Westhoff, 1978).
The result also revealed that the average bacteria count from nono, fura and fura da nono ranges between 3.0 -4.7 x104 cfu/ml. The inoculum load of fungal isolates ranges from 1.0 x 104 to 2.9 x 104 cfu/ml and yeast count ranges from 0.0 x 104 cfu/ml in fura to 5.3 x 104 cfu/ml in fura da nono (Table 2). All the samples were found to harbour coliforms. Odunfa (1988) reported that Staphylococcal levels of 108/ml is considered potentially hazardous, however, the microbial levels obtained in this report which is 104 could be considered hazardous to consumers because of the possibility of the presence of enterotoxigenic strains.
The mean pH and titratable acidity of nono and "fura da nono" ranges from 3.1 to 4.6 and 0.005 to 0.092 as show in Table 3. The overall low pH range of 3.1-4.6 obtained for the samples could account for the low microbial counts obtained. This result is in agreement with the report of Umor et al. (1988). The pH of nono in this report was however lower than that reported for Yoghurt by Odunfa (1988).
The possible sources of contaminating organisms associated with these products could be traced to the use of the old portion of previously fermented nono as starter and the use of well and stream water for processing. The contaminating organisms could also be through air microflora which stick to the smoothening stick, calabash spoons and bowls used for the sale of the products. Moreover, normal human flora of the customers could also serve as contaminants especially when one bowl is used for mixing the product for all customers without cleaning between use.
In order to prevent contamination of fura da nono by E. Coli, Staphylococcus
sp, Streptococcus sp and B. cereus, the local Fulanis who
are the major producers should be educated on sanitary practices during milking
of cows and further processing. The use of portable clean water where available
should be encouraged. The calabash spoon and
Copyright 2001 The Journal of Food Technology in Africa, Nairobi
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