COMPLETE SCHOOL PROJECT TOPICS & MATERIALS :
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CHAPTER ONE
INTRODUCTION
- Background of the study
Fish is a vertebrate animal, living in fresh and seawater. It is one of the main sources of animal protein foods available for human consumption. Most of the catch comes from oceans, seas, rivers and lately from man-made ponds. It is a highly nutritious food of about 60-80% water, 15-25% protein, 11-22% fat, 20% mineral and 1% carbohydrate. It is often cheaper than meat and so it is a rich protein source for both the poor and the wealthy.
In Nigeria, fish and fish products constitute more than 60% of the total protein intake in adults, especially in the rural areas, and they supply a good balance of protein, vitamins and minerals. Fish has a caloric content of relatively 10%, which enhances its value, as well as its role in the nation’s nutrition (Akinneye et al., 2007).
Microbial flora of fish depends on the microbial content of the water in which they live as the slime that covers the surface of fish has been found to contain great variety of bacteria general. Many dangers therefore exist if fish harvested from polluted water is eaten raw, and because of the high microbial load of freshly harvested fish it is susceptible to rapid spoilage. Hence preservation of fresh fish becomes very important. This can be achieved by freezing, drying through smoking and sun-drying, canning, etc.
Smoking simply means a heating process that dries the fish to preserve it from spoilage. Most dry fish consumed in Nigeria are smoked. Smoking of fish from smoldering wood for its preservation dates back to civilization. The steps in the smoking process are necessary not only for safe preservation, but also to produce good flavor and aroma. Hence, smoked fish and fresh fishes are less prone to microbial spoilage than fresh fish. However spoilage still occurs as a result of growth of microbes due to partial dehydration during smoking.
Consumption of fish and fish products is recommended due to good digestibility and the high content of polyunsaturated fatty acids. Fishes are a rich source of protein commonly consumed as an alternative source of protein due to the higher cost of meat and other sources of animal protein (Oluwaniyi and Dosumu, 2009). Fish has lower cholesterol content when compared with meat and thus often recommended for consumption especially among the adult population (Harris, 1997). The marine fish is generally cheaper and more abundant when compared with fresh water fishes, which are relatively more expensive in Nigeria (Oluwaniyi and Dosumu, 2009). Fish is a highly perishable food and so, many strategies have been developed to limit its spoilage (Gómez-Estaca et al., 2009). According to KumoluJohnson et al. (2010) various food preservation techniques have been utilized to improve the microbial safety and extend the shelf-life of fish in general including freezing, chemical preservation, salting, smoking, frying and filleting. However, smoking is the most popular method of fish processing (Bako, 2004). Food is considered to be microbiologically unsafe owing to the presence of microorganisms which may invade human body (e.g Salmonella, Escherichia coli, Listeria monocytogenes, etc) and also those that produce toxins ingested with a food such as Staphylococcus aureus, Clostridium botulinum and Bacilus cereus (Ofred, 2009). The growth of these pathogens may not necessarily results in food spoilage. Hence the absence of deleterious sensory changes cannot be used as an indicator for food microbiological safety (Border and Norton, 1997). Consequently many outbreaks are caused by bacteria originating in the animal/human reservoir including Salmonella, Shigella, E. coli, and Staphylococcus aureus, (Huss et al., 1997). Generally fish and shellfish are common vehicles of transmitting food borne diseases.
Contamination of fish and other fishery products by microbes has been a serious threat to human health. There are four main factors responsible for fish spoilage once it is out of its natural habitat (water) and these include: Autolysis which usually precedes bacterial spoilage and involves the breakdown of protein and lipids to amino acids and fats by muscle enzymes. The activity of microorganism is another factor which uses the amino acid produced by autolysis for proliferation. Others are chemical deterioration and insect attack which cause considerable deterioration.
However, spoilage of fresh and highly preserved fish products is mostly caused by microbial action. Foods of high sugar/salt contents are therefore most likely to be spoiled by any kind of microbe. It has been reported that serious disease outbreak had occurred in both man and animals after consuming some dried fish feed and food. This could be as a result of disease causing microorganism like Escherichia coli, Salmonella typhi, Vibrio cholera which results from poor handling/cross-contamination and improper processing practice of ready to eat “smoked fish and fresh fish” products. Other microorganisms of primary concern are Listeria monocytogen and Clostridium botulinium. Extensive handling provide opportunities for other food borne pathogens to contaminate products if sufficient attention is not given during smoking process.
This work therefore tends to investigate the level of sanitation maintained by handlers during processing and storage of smoked fish and fresh fish sold in Akwa Ibom State.
1.2 Statement of the problem
The problem of fish in Nigeria however, is its high rate of perishability especially since the relative ease of preservation is not readily attainable, hence the difficulty in handling. Generally, the different preservation methods are: drying, smoking, freezing, chilling and brining but the common method in Nigeria is smoking (Akinola et al., 2006).
Smoking (the commonly adopted method of preserving fish in Nigeria), as an international source of foreign exchange is gradually losing ground (Al – Jafali and Opara, 2006); this is because exportation of smoked fish and fresh fish to developed countries is becoming increasingly stringent due to the emergence of food safety and agricultural health standard, along with the fact that buyers keep changing their requirements. The quality of processed food usually depends on the processing and handling techniques employed (Al-Jafaili and Opara, 2006). This is particularly true of smoked fish and fresh fish in view of the presence of endogenous organisms. Food poisoning organisms can multiply profusely in foods without initially altering the appearance, taste or odour.
A large number of people suffer from gastro-intestinal upsets annually, as a result of eating contaminated food which leads to a considerable loss of man-hour with accompanying consequences. Sometimes death occurs.
In many instances, outbreaks result from lack of understanding of food hygiene in the preparation, cooking and care of food. In order to avert such outbreaks, safety evaluation is necessary. Determination of pathogenic loads, by microbial tests for ascertaining risk level as well as potential sources in the smoked fish and fresh fish could be part of the palliatives.
1.3 Objectives of the study
The main objective of the study is to determine the microbial contamination on commercially prepared (sold) smoked fish and Fresh Fish in Akwa Ibom State.
Specifically, the study tends to;
- Assess the food safety knowledge, attitude and practices of smoke fish handlers along the fish value chains.
- Examine the microbial quality in smoked fish and fresh fish.
- Assess the presence and prevalence of microorganisms of public health importance
1.4 Significance/ Justification of study
Fish is one of the cheapest sources of animal protein in Nigeria and its production has the potential to make substantial contributions towards addressing the food and nutrition security challenges of the country (Amiengheme, 2005). In order to realize this potential, however, it is essential to understand the public health threats associated with the development and expansion of the fish value chains in Nigeria. Currently, ongoing research on animal sourced food value chains seemed to have focused mainly on high turnover livestock sectors, particular poultry and dairy industry, with little attention being paid to the fish sector. As such, one of the justifications for this research project was to generate information that would guide public health policy development for the Nigerian fish industry.
With tremendous increase in consumption of fish, there have been only a limited number of studies conducted which focused on hygiene and safety of both domestic fish and frozen fish value chains. The results of the studies therefore addressed the shortfalls in information regarding the food safety and hygiene measures of stakeholders in fish value chains in Akwa Ibom State metropolises.
The study was designed to provide useful potential risks associated with consumption of fish, it‘s processing and handling practices through evaluation of the microbial burden. The level of microbial contaminants along fish value chains will provide baseline information for policy development on the hazard analysis and critical control points (HACCP). Cultural, biochemical and molecular evaluation will emphasize the presence of these organisms and biochemical characteristics such as the burden, pathogenic strains, and resistance profile. Antimicrobial resistance profile of circulating strains of S. aureus and Salmonella spp. could help clinicians in selecting the efficient antibiotics in cases of infections. The basic phenotypic characteristics of these agents to antibiotics will help in development of meaningful strategy for disease surveillance and control programme.