Quality of Cassava Fufu Sold in Abakaliki Metropolis

Cassava fufu as sold and consumed in Abakaliki metropolis was evaluated for its shelf stability and microbial quality. Ten different samples of cooked cassava fufu were purchased from 5different sellers in Abakaliki metropolis, Ebonyi State. This was divided into wrapped and unwrapped (five wrapped in low density polyethylene bags and five unwrapped) cassava fufu and stored at ambient temperature in the Food Microbiology Laboratory of the Department of Food Science and Technology. These samples were assayed for both chemical and microbial qualities. The chemical analyses included Moisture, pH and TTA. The result revealed that moisture content of the samples ranged from 52.5-54.9%. The values of the pH ranged from 3.70-6.40, while the values of Total Titrable Acidity (TTA) ranged from 0.004-0.063%. The result of the microbial analysis showed that there were increase in the fungal (1.0×10 (cfu/g)) and bacterial (2.91×10(cfu/g)) counts as the storage time increased with the control having microbial load within the acceptable levels. The fungal isolates from the samples include Aspergillus niger, Aspergillus flavus and Penicillium spp, while the bacteria isolates from the samples include Bacillus spp and Staphylococcus aureus. Statistically, there were significant difference (p<0.05) in appearance of the fufu as storage time increased. This study therefore will encourage good manufacturing practices among the producers and marketers to reduce proliferation of pathogenic microorganisms in processed cassava fufu.


INTRODUCTION
Cassava (Manihot esculenta Crantz) is among the major root crops in the world and is cultivated in all tropical and subtropical regions particularly in Africa, Asia and South America where it provides over 50% of the average daily calorific intake (De Bruijn and Fresco, 1989).Cassava root is more perishable than other tuber crops such as yam and sweet potato because it has no dormancy and it senesces soon after harvesting (about 2-5 days), followed by microbial deterioration 3-5 days later (Poulter, 1995;Nweke, 1994).Cassava tuber varies widely in their cyanogenic contents with most varieties containing about 15 to 400 mg of HCN per Kg of fresh weight (Padmaja, 1995).
Cassava fufu is a fermented wet paste made from cassava.It is ranked next to gari as an indigenous food of most Nigerians.Cassava fufu has a very strong odour and is an important staple food widely eaten in Nigeria, many parts of West Africa and the Tropics (Sanni, 1989).Cassava fufu has gained popularity and acceptance to the point that it is being sold in the market and hawked in the streets of most cities and metropolis of South East, South-South and South-West Nigeria.The cooked ready-to-eat cassava fufu is wrapped in low density polyethylene bags that are transparent and packed in plastic buckets, while some quantities are displayed on plastic/stainless trays for prospective buyers.Cassava fufu as sold in the market is a ready-to-eat food that does not require further heat treatment before consumption.Moreover, it is convenient as no further processing is needed.The fufu as it were, is usually exposed to sunlight and the shelflife depends on the vagaries of weather.As microorganisms are known to thrive under different temperatures, the fufu is prone to weather changes giving rise to the development of some microorganisms in the fufu.Besides, the fufu usually lasts for 4 to 7 days before the sales could be finished.Thus, the fufu is exposed to post processing contaminations just like every other food largely due to poor handling and marketing/channel of distribution.Hence, this study is undertaken with a view to evaluating the post processing qualities of cassava fufu as sold and marketed in the study area.The aim of this study among other things is to determine the quality of cassava fufu as sold and consumed in Abakaliki Metropolis.

Collection of samples:
Cassava "fufu" was purchased from five different sellers in meat-market, Abakaliki metropolis.Two samples each were purchased from those sellers, making a total of 10 samples.The fufu was collected in a low density polyethylene bag and transferred into different plastic containers.

Sample preparation:
The samples were divided into two; five wrapped in low density polyethylene bags and the other five unwrapped and then placed in different plastic containers with covers.The samples were labeled appropriately for easy identification and kept under room temperature.Samples were drawn in alternate days for microbial analysis and every day for chemical analysis.

Analysis of samples:
The samples obtained were assayed for Chemical analyses (Moisture, pH and Total titratable acidity), Microbial analyses (Characterization and Identification of Isolates) and Sensory evaluation.

Chemical analysis:
The chemical analysis which included moisture content, pH and Total Titrable Acidity (TTA) were analysed according to Association of Official Analytical Chemists (A.O.A.C.) (1990) methods of analysis.

Microbial analysis:
One gram each of the fufu was separately homogenized in 9ml of distilled water.Tenfold serial dilution of each sample was performed until 10 -4 level of dilution was obtained.1ml of the lowest dilution (10 -1 ) and other dilutions were pour plated on plates of nutrient agar and Sabouraud dextrose agar for the determination of microbial counts in each sample of the respective agar media, followed by incubation at laboratory (ambient) temperatures for 48 and 72 h for bacterial and fungal growths respectively.Total viable counts of bacterial and fungal were determined by enumerating the colony forming units (cfu/g) at the end of the incubation period using the following formula as described by (Jideani and Jideani, 2006 The microorganisms isolated were sub-cultured by repeated streaking into sterile nutrient agar, macConkey agar slants for bacterial and Sabouraud dextrose agar slants for fungal until pure cultures were obtained.

Characterization and identification of isolates:
The isolation and identification were done using the method of Ogbulie et al. (2005) and International Commission on Microbiological Specification for Food (I.C.M.S.F.) (1978).Bacterial isolates were characterized and identified by initially examining colonies' morphology on their cultural properties followed by biochemical tests (Motility, citrate, coagulase, gram stain, catalase and oxidase).The fungal isolates on the other hand, were characterized by their cultural properties stained with cotton-blue lacto phenol solution and morphological observations under low power objective lens.
Sensory evaluation: A nine point Hedonic scale with 1 corresponding to dislike extremely, 5 corresponding to neither like nor dislike and 9 corresponds to like extremely was used to analyse the differences in the samples by twenty five (25) panelists.The attribute of interest was change in appearance of the fufu during storage.
Statistical analysis: Data obtained in colony forming unit per gram (cfu/g), pH and total titratable acidity were analysed using statistical package for the social sciences (SPSS version 20).The mean values were separated using Duncan Multiple Range Test at (p = 0.05).
Table 1 shows the pH values of the cassava fufu.The pH of the fufu ranged from 3.70 to 6.80.This pH range is in agreement with the findings of previous researchers (Odom et al., 2012).The pH values indicated that the fufu maintained acidic pH despite the source and storage time.These pH ranges will support the growth of pathogenic microorganisms.Release of ammonia by spoilage microorganisms has been linked to the increasing pH of food during storage (Sarkar et al., 1993;Olawepo et al., 2001).Moulds constitute the greatest danger to food spoilage.This is because mould can grow over a wide range of pH values than most yeast and bacteria.Fermentative yeast grows well at pH levels between 4-4.5 and film yeast grows well at pH 3.4-3.6while bacteria grow well at pH near neutrality (Umeh, 2009).The pH result indicates that the pH of the fufu were significantly different (p>0.05) at zero day despite the source.But on day 1 the pH remained virtually non significant (p<0.05).The changes in pH were independent of the storage conditions.
The result of the total titrable acidity of the sample is shown in Table 2.The values of the titrable acidity like the pH fluctuated from day 0 to day 8. Odom et al. (2012) reported that the total titrable acidity of cassava fufu stored for several days decreased as the pH increased.This fluctuation in pH and titrable acidity could be attributed to microbial activities, biochemical reactions and environmental conditions such as fluctuation of the ambient temperature, presence of carbon (iv) oxide, lack or presence of oxygen and storage humidity http://www.researchgate.net.(October, 2013).These determine the type of metabolites produced by the different microbes.Lactic acid bacteria in cassava fufu produce acetic acid, lactic acid, ethyl alcohol and carbon (iv) oxide from the available carbohydrate consumption that cause pH decrease http://www.researchgate.net.(October,2013).Also, if a microbiological oxidation of organic substance which contain sulphur or nitrogen takes places, then inorganic acid such as tetraoxosulphate (vi) acid and trioxonitrate (v) acid are developed therefore resulting in decrease the pH.
Table 5 shows the dominant microorganisms isolated from the fufu.The organisms include Staphylococcus aureus, Bacillus cereus, Aspergillus flavus, Aspergillus niger and Penicillum spp.Isolation of these organisms may be attributed to poor handling during post processing and storage.Contamination by Staphylococcus aureus could be from human skin, mouth when coughed, nose when sneezed (Umeh, 2009).S. aureus produce a number of disease-causing factors such as coagulase, alpha exotoxin and haemolytic beta toxin which are the principal agents in food borne intoxication.The symptoms of staphylococcal intoxication include extreme distress, nausea, diarrhea and vomiting (Okaka et al., 2006).Bacillus cereus is an inhabitant of soil, leaf surface and wrapping materials (Odom et al., 2012).B. cereus produces an exotoxin which causes an intoxication characterized by abdominal pain, flatulence, diarrhea, headache, dizziness, vomiting and dehydration.It occurs from contamination from packaging materials as well as eating cold fufu after being held at room temperature for several days/hours (Umeh, 2009).It is worthy of note that the fufu as marketed in the study area is usually eaten as purchased thereby exposing consumers to bacterial contamination.Aspergillus spp.Found growing in the fufu could lead to mycotoxins with concomitant mycotoxicosis.
The physical change in the cassava fufu is as presented in Table 6.On days zero, one and two, no visible changes were observed on the cassava fufu.But from day 3, there were changes in appearance of the fufu.The change in appearance could be attributed to biochemical reactions and different microbial developments (Jideani and Jideani, 2006).The change in appearance increased as storage days increased.However, the wrapped fufu had firm texture, good appearance and tolerable odour at 3 rd day of storage than unwrapped fufu.This could be attributed to low permeability of the cellophane to air, oil and/or grease, water vapour and microorganism.
Table 7 shows the mean sensory scores of appearance of the stored cassava fufu.The result showed that there was a significant difference (p>0.05) on the fufu as the storage time increased.Thus, increased storage of cassava fufu will not only increase the microbial proliferation but will reduce consumer acceptability of the fufu.

CONCLUSION
Hawking and storage of cassava fufu at ambient temperature for more than two days predisposes the fufu to microbial growths and loss of acceptability due to poor appearance.Besides, the type of microorganisms found on the stored cassava fufu could lead to some health hazards.Thus, cassava fufu intended for marketing should be stored for not more than two days and wrapped properly using low density polyethylene bag.Sanitary/health workers should be alive to their responsibilities by ensuring that processors and marketers of processed cassava fufu develop the culture of good manufacturing practices and general cleanliness to reduce contamination of the product.
forming unit per gram (cfu/g) n : Number of colonies d : Dilution blank factor v : Volume transferred to plate

Table 1 :
pH of cassava fufu stored for 8 days under room temperature Means within the same rows that have the same superscripts are significantly not different from one another (p>0.05)

Table 2 :
Total titrable acidity of cassava fufu stored at room temperature

Table 5 :
Biochemical characteristics of microbial isolates

Table 6 :
Changes in the physical appearance of stored cassava Fufu