ABSTRACT
Post-harvest loss of fish is a major factor of economic and protein wastages in the developing countries. In this study, the effects of different common methods of preservation, smoking which is the nutritive value of the African mud catfish, Clarias gariepinus were determined. Live samples of C. gariepinus were obtained from the fish farm of the Department of Agricultural Education, Federal College of Education, Osiele, Abeokuta, Ogun State. One portion of the harvested fish was smoked, using a smoking kiln at 60-70 oC for 24 hours and stored in a polythene bag for further use. Another batch of C. gariepinus was preserved immediately after harvest in the freezer at less than -0 oC for 20 days. The third batch of the live fish was sacrificed immediately and prepared for biochemical analysis. The proximate compositions of the fish samples were determined according to AOAC (1995). The percentage moisture, protein, lipid, ash, crude fibre and carbohydrate contents obtained in the smoked fish samples were statistically different (P > 0.05) to the fresh fish samples (control). Similarly, there were significant differences in the percentage protein, lipid and crude fibre values in the frozen fish samples when compared to the fresh fish samples but there were no significant changes (P
TABLE OF CONTENT
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the Study
1.2 Problem statement
1.3 Objectives of the Study
1.3.1 General Objective
1.3.2 Specific objective of the study
1.4 Significant of the Study
1.5 Scope of the Study
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Historical Background of Aquaculture
2.1.1 Fish Farming in Africa
2.2 Fish Seeds and Fingerlings Production
2.3 Site Selection for Fish Farm Establishment
2.4 Management of Fish Enclosures for Fish Rearing
2.5 Fish Culture Systems Practice
2.6 Water Quality in Fish Farms
2.7 Common Fish Diseases in Fish Farms
2.8 Feeding in Fish Farming Systems
2.10 Fertilizer Application in Fish Ponds
2.11 Sustainability of Fish Farming
2.11.1 Effluent Control and Waste Treatment in Fish Farms
2.12 Fish Handling and Preservation
2.12.1 Fish Handling
2.12.2 Fish Preservation
2.13 Smoking: Processing
CHAPTER THREE
3.0 Materials and Method
3.1 Experimental Sites
3.2 Experimental Diets
3.3 Experimental Materials
3.4 Procurement of Experimental Animals
3.5 Experimental Procedure
3.6 Fish Smoking Process
3.7 Proximate Analysis
3.8Physico-Chemical Analysis
3.9 Preparation of Fish Samples
3.10 Smoking Technique
3.11 Freezing Method
3.12 Determination of Potassium (K) And Iron (Fe) Contents
3.13 Determination of Phosphorus Content
3. 14 Determination of Vitamin C
3.15 Statistical Analysis
CHAPTER FOUR
4.0 Results and Discussion
4.1 Some of the Smoking Technology
CHAPTER FIVE
5.0 Conclusion and Recommendations
5.1` Conclusion
5.2 Recommendations
References
LIST OF TABLES
Table
Proximate compositions of smoked and frozen samples of catfish (C. gariepinus)
Mineral (μg/ml) and Vitamin (mg/ml) compositions of smoked and frozen catfish,
Clarias gariepinus
LIST OF FIGURE
Flow chart for traditional fish smoking (Crapo, 2011))
LIST OF PLATE
Plate
1. harcoal Smoking Technique
2. Modern Oven Technique
3. Wood/Mud Smoking Technique
4. Halved Drum oven with smaller stoke hole.
5. Improved Drum Oven 43
6. Cylindrical Mud Kiln. 45
7. Cabinet Kiln 47
8. Display of smoked fish.
. CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Fish is an extremely perishable food item (Agbon et al., 2002). Soon after death, fish begins to spoil. In the healthy live fish, all the complex biochemical reactions are balanced and the fish flesh is sterile. After death however, irreversible change that results in fish spoilage begins to occur. The resultant effect is the decomposition of the fish (Akinola et al., 2006). Various factors are responsible for fish spoilage. The quality of capture is important at determining the rate of spoilage. Notably are the fish health status, the presence of parasites, bruises and wounds on the skin and the mode by which the fish was captured. The caught fish quality depends on the handling and preservation, the fish received from the hands of the fishers after capture. The handling and the preservation practice after capture affects the degree of spoilage of the fish (Akinneye et al., 2007). The quality of the freshly caught fish and its usefulness for further utilization in processing is affected by the fish capture method. Unsuitable fishing method does not only cause mechanical damage to the fish, but also creates stress and the conditions which accelerate fish deterioration after death. Fish is highly susceptible to deterioration without any preservative or processing measures (Okonta and Ekelemu, 2005). Emokpae (1979) reported that immediately the fish dies, a number of physiological and microbial deterioration set in and thereby degrade the fish. Fish is a major source of protein and its harvesting, handling, processing and distribution provide livelihood for millions of people as well as providing foreign exchange earning to many countries (Al-Jufaili and Opara, 2006).
Appropriate processing of fish enables maximal use of raw material and production of value-added products which is obviously the basis of processing profitability. Freshwater fish processing, like the processing of the other food raw materials should: assure best possible market quality, provide a proper form of semi-processed final product, assure health safety of products, apply the most appropriate processing method and reduce wastes to the barest possible extent. Akinneye et al. (2007) and Davies (2005) reported that the development of appropriate fishing machinery and techniques that employed effective production, handling, harvesting, processing and storage, cannot be over-emphasized especially in the age when aquaculture development is fast gathering momentum in Nigeria. The need to mechanize fish processing techniques has drawn the attention of national agricultural research to devote utmost interest and resources to engineering research in operation, to minimize the drudgery, reduce labour operation, and unsanitary and inherent unhygienic handling that are mostly involved in the traditional manual operations.
Thus, period of fish scarcity is often encountered especially during the flood and raining seasons, during which fish are in short supply. Thus, it is imperative to process and preserve some of the fish caught in the period of abundance, so as to ensure an all year round supply. This will invariably reduce post harvest losses, increase the shelf-life of fish, and guarantee a sustainable supply of fish during off season with concomitant increase in the profit of the fisher folks. Akinola et al. (2006) reported different types of preservation methods; drying, smoking, freezing, chilling and brining. But the most prominent fish preservation is smoke drying. This could be adduced to the fact that most of the fish communities have no access to electricity to freeze their products. Fish spoilage is brought about mainly by, the enzymes present in the live fish. The enzymes begin to break down fish tissues. Prior to death, the enzymes were involved in the digestion of ingested food and all enzymatic reactions are controlled. In the dead fish, the control system fails and the enzymes begin to act on the alimentary system and fish flesh, thereby resulting in soft destructive changes. This process is referred to as autolytic spoilage (FAO, 1985).
Bacteria are present in the gut, gills and skin surfaces of live fish. The live fish defense mechanism is able to combat the action of these bacteria. However, some after death, this defense mechanism also fails. Consequently, the bacteria invade the gut, gills and skin, and cause the decomposition from within and the exposed surfaces of the fish. Enzyme and bacteria spoilage of fish can be reduced or temporarily halted by various techniques. The traditional and popular methods employed include:
· Temperature reduction by the use of ice (freezing or ice blasting)
· Drying to reduce or completely remove water
· Salting to reduce water and stop enzymatic decomposition
Application of heat e.g. canning and smoking to destroy the enzymes and kill all bacteria All the techniques employed in the preservation of fish can be used in isolation or in combination. For example, fish may be generally held in ice before canning, sun drying or smoking. Akinola et al., (2006) reported that despite the rudimentary nature of process of traditional methods, lack of control over the drying rate, sometimes results to under-drying or over-drying, expose the fish to unexpected winds, dust, dirt, insect infestation, and contaminants such as flies. These methods still remain predominant in Nigeria. To reduce post harvest losses and to improve the quality of fish and fishery products, traditional processing technology must be improved upon in Nigeria. This includes upgrading the traditional fish processing technology and adoption of solar dryer. Artificial dryers such as solar dryer, kiln, oven and so on, have long been in existence, some of them are powered electrically, by sun, gas or natural fuel such as firewood, charcoal, wood and saw dust (Bolaji, 2005). The drying of fish in oven consists of a period of several hours in which the fish is cooked and dried with low burning fire for a period, producing only a moderate amount of smoke. The length of this latter period varies with the required keeping quality. The moisture of the dried products varies between an estimated 40% in the higher ranges and 10-20% in lower. The quality of the product is judged on degree of drying, appearance, damaged and insect infestation is influencing the price. Smoked fish as source of foreign exchange is gradually losing ground. This is adduced to the fact that exportation of processed fish to developed countries is becoming increasingly stringent because of the emerging set of Food Safely and Agricultural Health Standard, along with buyers changing their requirements (Oyelese, 2006).
1.2 OBJECTIVE OF THE STUDY
1.2.1 General Objective
The general objective of this study is to determine the effect of different smoking processes on the fish production.
1.2.2 Specific Objectives
The specific objectives of this study are to:
i. Examine the various available techniques of preserving fish by smoking
ii. To assess the effect of various fish smoking techniques on consumers acceptability
iii. To make useful recommendations based on the outcome of the study.
1.3 Significance of the Study
This study will go a long way in enlightening fish farmers on the most economical and preferable fish smoking methods which can help to reduce post harvest losses and to improve the quality of fish and fishery products. This includes upgrading the traditional fish processing technology and mechanical means of smoking.
1.4 Scope of the Study
This practical work was carried out in the Animal Laboratory of Agricultural Science Department, Federal College of Education Osiele, Abeokuta, Ogun state. This work focused mainly various fish smoking techniques. The research work is limited to Federal College of Education, Osiele and its environment.