Fish are classified as any of the cold-blooded aquatic vertebrates of the super class Pisces typically showing gills, fins and streamline body. In addition Fish also refers to any other form of marine or fresh water animal that can be used for human consumption. Fish is also an important part of a healthy diet since it contains high quality protein but typically presents a low fat percent when compared to other meat.The production and consumption of fish in Nigeria has been a major source of animal protein which has competed favorably with meat. Catfish (Clariasgariepinus) has been reported to be a very important fresh water fish in Nigeria. It has enjoyed wide acceptability in most parts of the country because of its unique taste, flavor and texture. It is widely distributed, extensively cultivated in ponds. Fish is one of the best sources of proteins, vitamins and minerals and are essential nutrients required for supplementing both infant and adult diets (Abdullahi et al., 2009)
In Nigeria, Fish can be eaten, preserved, or processed (smoked) and form a much cherished delicacy that cuts across socio-economic, age, religious and educational barriers (Adebayo-Tayo et al 2012). As earlier reported, the microbial flora associated with freshly harvested fish is principally a function of the environment in which the fish are caught and not of the fish are caught and not of the fish species, hence the indigenous microbial population of fish can vary significantly (Shewan 2014). A similar report on fish confirmed that fish because of their soft tissues and aquatic environment are extremely susceptible to microbial contamination. Millions of bacteria, many of them potential spoilers are present in the surface slime,on the gills and in the intestines of live fish although the flesh itself is normally sterile. Bacteria growth and invasion on the fish are prevented by the body’s natural defense system during life but after death the defense system breaks down and the bacteria multiply and invade the flesh (Abolagba and Uwagbai 2011).
Preserving food and other perishable products like fish and meat generally involves processes that impede growth of microorganisms either by addition of inhibiting agent or adjusting storage conditions by freezing or drying. Smoking is preferred microbiologically safe method of fish preservation compared to fresh fish which have a heavy pathogenic microbial load. In preserving fish by smoking, water activity in the fish is lowered to the point where the activity of the spoilage organisms is inhibited and the wood smoke add some microbial inhibitory substance like formaldehyde and alcohols. Therefore fish requires proper handling and preservation to increase its shelf life and retain its quality and nutritional attributes. Immediately all fish is caught, it loses its natural resistance to attack by microorganism and also starts to undergo both physical and chemical changes that in returns bring changes in appearance,taste,smell and texture( Laucas,2013).
The autochthonous bacterial flora of fish is dominated by gram-negative genera including: Acinetobacter,Flavobacterium, Moraxella, Shewanella, and Pseudomonas. Members of the families Vibrionacea (Vibrio and Photobacterium) and the Aeromonadacea (Aeromonas spp.) are also common aquatic bacteria, and are typical of the fish flora. Gram-positive organisms such as Bacillus, Micrococcus, Clostridum, Lactobacillus and Coryneforms can also be found in varying proportions. Human pathogenic bacteria can be part of the initial micro flora of fish, posing a concern for sea foodborne illnesses: especially organisms naturally present on fish (Feldhusen,2012). Fish and shellfish poisonings are due to toxins in the flesh either intrinsically present or derived from the food they eat. This is true for puffer fish poisoning (caused by tetradotoxin), ciguatera (caused by ciguatoxin and possibly other toxins) and paralytic shellfish poisoning (PSP) (caused by saxitoxin and other toxins). Fish and shellfish products are a minor source of bacterial foodborne disease in North America, the United Kingdom, and Australia but there is a continuing high relative incidence of bacterial foodborne disease from fish products in Japan and probably in Southeast Asian countries where fish are commonly eaten raw. A number of different Vibrio species have been implicated in foodborne illness resulting from eating seafood. These includeV. parahaemlyticus, V. vulnifcus, V. chloreae, V. fluvialis and V. alginolyticus(Ehiri, Azubike, Ubbaonu & Anyanwu,2013). Disease due to Vibrio species is usually associated with situations where large populations of living Vibrio are present on seafood, either in the raw state where fish and shellfish are eaten uncooked or in decontaminated cooked products which are stored at temperatures that permit growth. However, infective population levels of Vibrio can occur on freshly harvested fishes, particularly where water quality is poor and temperatures are high. Contaminated shellfish maybe a source of hepatitis. Poor post-harvest technology (handling, preservation and processing) have been reported earlier to have the ability to cause unhealthy situation resulting to massive spoilage. An estimate of 40% post-harvest losses of total fish landings have been reported in Nigeria (Akande, 2013). (Mayboom, 2009) similarly reported that 15% of the total fish catch in kanji lake is lost because of spoilage and consumers. Salting has been traditionally used as a method of fish flesh (Horner, 2011). The salt mainly contains chloride ions that are toxic to some microorganisms (Leroi et al,2000 goulas and kontominas, 2015).This technique is hence used to preserve fish from spoilage owing to tissue autolysis and microbial action. Bacteria spoilage is for example characterized by softening of muscle tissue which can however be prevented by salt because it forms a more membranous surface that inhibit the growth of microorganisms (Rorvik, 2011). Although salting reduces the rate of autolysis, it does not completely stop enzymatic action that increase withincreasing temperature. Even though fish are smoked, the heat supplied might not kill all the pathogens. Smoked fish could be stored satisfactorily for three weeks at 5oC and less than one week at 100c (Poulter et al,2010). The need for proper refrigeration cannot be over emphasized. The finished products should not be distributed until it has been properly cooled to 4.20C or below. Furthermore, because of the perishable nature of smoked fish, it is imperative that the finished product can be maintained in a refrigerated condition at 4.20C until consumed (Otwell et al, 2013). Most food poisoning outbreaks, related to smoked fish have been related to abusive storage temperature condition. Smoking is the preferred method of fish preservation in most rural areas and riverine fishing communities especially in Delta state of Nigeria.
1.1 PROBLEM STATEMENT AND JUSTIFICATION
Fish is one of the main source of protein for the people in Nigeria especially those living around the riverine areas and given the prevalence of water and food-borne diseases in Nigeria. It is in order that all possible infection routes of the pathogens be investigated and assessed and possible mitigation measures outlined. It is with this in mind that the research proposal was developed. Fish also forms a major form of employment. It’s transportation from landing sites to the markets is done using baskets, manila sacks, and containers and to a lesser extent tin cans. Most of the landing sites lack electricity and this makes it impossible for the fish dealers to have a cold storage facility. In addition, roads serving these areas are very poor and inaccessible during rainy seasons. These have led to a scenario where the fish that is not sold fresh to the processing industries or individuals, being processed in some way. Processing is done in the form of smoking, sun-drying, dry salting or frying in Nigeria. The treatments employed in the processing are mostly inadequate resulting in the spoilage of the processed products.
The belief most people have is that smoked fish is sterile and can be eaten without further heat processing. In fact some people eat the fish at the market before any post-smoking processing is done. The study was aimed at understanding the safety of smoked fish products during and after the smoking process. It identified microorganisms that contaminate smoked fish products and made appropriate recommendations for mitigation. The findings of the study should be used to design steps necessary in lengthening shelf-life of smoked fish products and ways of avoiding smoked fish contamination with microorganisms (Feldhusen,2012)..
- OBJECTIVES OF THE STUDY
The objective of the study is to assess and compare the Bacteriological quality of fish sample and isolation of possible microorganisms associated with smoked fish with the view of assessing their level of public health implication vended in Awka metropolis and Hot water washed spoilt smoked fish. Specifically, the study will determine
- Salmonellacounts in the smoked fish.
- Microbial faecal count of the smoked fish.
- Staphylococcus count found in fish.
- Aerobic count of the smoked fish.
- Coliform count of the smoked fish.
- Vibrio count of the smoked fish.
1.3 SCOPE AND LIMITATIONS OF THE STUDY
1.4 SCOPE OF THE STUDY
The study on the bacteriological quality of smoked fish would cover the bacteria that affect smoked fish and its public health implications
1.5 LIMITATIONS OF THE STUDY
Time constraint: The researcher will simultaneously engage in this study with other academic activities. This would consequently cut down the time devoted for the research work.
Financial constraint: Insufficient funds tend to impede the efficiency of sourcing and collecting the relevant material and literature work for the study