1.1 Introduction
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).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research questions, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Fish is highly nutritious with high protein content. However, it is a suitable medium for growth of microorganisms, if poorly processed (Oparaku and Mgbenka, 2012). The growth of microorganisms and other non-microbial activities such as lipid oxidation contribute to the deterioration of fish products (Martin, 2010). An increase in the ambient temperature triggers favourable conditions for microorganisms to thrive, which reduces the quality of fish and its potential keeping time leading to food loss (Abolagba et al., 2011).
Preserving food and other perishable products like fish and meat generally involves processes that impede growth of microorganisms either by the addition of growth inhibiting ingredients or adjusting storage conditions by freezing or drying (Akise et al., 2013). Processing methods affect the microorganisms in fish in different ways, resulting in different types of micro-flora and different risks from spoilage organisms and pathogens.
In dried fish, the micro-flora are prevented from growing by the storage method used and the product may have a long shelf life in the preserved state. However, the microbial load of fish rarely indicates the quality of the fish, but gives an indication of the risk of spoilage induced since each of the organisms has different ways of affecting the health conditions of consumers of such contaminated fish (Gram et al., 2015).
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” products. Other microorganisms of primary concern are Listeria monocytogen and Clostridium botulinium. Extensive handling provides opportunities for other food borne pathogens to contaminate products if sufficient attention is not given during smoking process.
As result there is a need to investigate microorganisms such fungi that are associated to fish spoilage. This necessitated this study into investigating fungi associated with smoked dried fish vended in Eke - Awka Market in Anambra state.
1.3 Statement of Problems
Investigation revealed that 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 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 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 could be part of the palliatives.
1.4 Aim and Objectives of Study
The aim of the study is to investigate the Fungi Associated with Spoilage of Smoked Dried Fish. In achieving this aim, the following specific objectives were laid out as follows:
- To identify the fungi associated to smoked dried fish; and
- To isolate the fungi's associated to smoked dried fish vended in Eke-Awka market.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- Are there fungi associated to smoked dried fish?
- How can fungi's associated with smoked dried fish vended in Eke-Awka market be isolated?
1.6 Significance of Study
Smoked dried fish constitute a major source of animal protein for a vast majority of the population in Nigeria, particularly the rural areas. It is therefore important from toxicological points of view to investigate the growth and effects of fungi on smoked - dried fish.
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.7 Scope of Study
The scope of the research is focused on the Fungi Associated with Spoilage of Smoked Dried Fish in Nigeria.
1.8 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
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