1.1 BACKGROUND TO THE STUDY
Fish and seafood constitute an important food component for a large section of world population (Wafaa et al., 2011). They come after meat and poultry as staple animal protein foods where fish forms a cheap source of protein (Wafaa et al., 2011). Sea foods have traditionally being a popular part of the diet in many parts of the world and in some countries constituted the main supply of animal protein. Today, even more people are turning to fish as a healthy alternative to real meat (Adebayo-Tayo et al., 2012). Fish as an important food commodity in the international trade deteriorate rapidly especially when storage facilities are lacking. Fish is one of the most highly perishable food products (Sallam, 2007; Adebayo-Tayo et al., 2012). Fish can spoil from both outer surface and inner surfaces as fish stomach contain digested and partially digested food which can pass into the intestine (Emikpe et al., 2011). After fish is being caught and dying the immune system collapses and bacteria are allowed to proliferate freely on the skin surface and the stomach (Emikpe et al., 2011). The walls of intestines do break down sufficiently for bacteria to move into the flesh through the muscle fibre. During handling and storage, quality deterioration of fresh fish rapidly occurs and limits the shelf life of the product (Sallam, 2007; Adebayo-Tayo et al., 2012). The quality of fish degrades, due to a complex process in which physical, chemical and microbiological forms of deterioration are implicated (Sallam, 2007; Adebayo-Tayo et al., 2012).
Fish spoilage is a complex process in which physical, chemical and microbiological mechanisms are implicated (Hozbor et al., 2006; Adebayo-Tayo et al., 2012). Spoilage is the result of a series of changes brought about in the dead fish mainly due to enzyme and bacterial action. It starts in the fish as soon as the fish dies when caught. In areas where temperature is high, fish spoil within 15-20 hours depending on the specie and the method of capture (Adedeji and Adetunji, 2004; Adedeji, 2012). Fish is extremely perishable. It spoils easily. “Spoilage” can be defined as a change in fish or fish products that renders them less acceptable, unacceptable or unsafe for human consumption. Fish undergoing spoilage has one or more of the following signs: slime formation; discolouration; changes in texture; off-odours; off-flavours and gas production (Adedeji and Adetunji, 2004; Adedeji, 2012).
Preservation of fish is done to prevent spoilage. Since fish is very perishable, it is therefore, necessary to preserve fish if not consumed or disposed immediately (Adedeji and Adetunji, 2004; Adedeji, 2012). Fish preservation is the method of extending the shelf life of fish and other fishery products by applying the principles of chemistry, engineering and other branches of science in order to improve the quality of the products and control spoilage (Adedeji and Adetunji, 2004; Adedeji, 2012). Fish spoilage is mainly controlled by dehydration, lowering temperature, increasing temperature and using preservatives (Adedeji and Adetunji, 2004; Adedeji, 2012). To control spoilage, one avoid exposing the fish to sunlight. Keep them in a shaded area. Ice the fish immediately after they are caught to lower their temperature (Adedeji and Adetunji, 2004; Adedeji, 2012). Remove the gills and internal organs. Avoid soaking the fish too long in the water after death as this easily spoils the fish. Use mechanical refrigeration if there are facilities (Adedeji and Adetunji, 2004; Adedeji, 2012). Salting, smoking, drying and cooking are among the methods used in control of spoilage in fresh fish while salting is majorly used in dry fishes. However, this study will examine approaches into the prediction and control of the spoilage of fresh cured and dried tropical fishes in Nigeria.
1.2 STATEMENT OF THE PROBLEM
Fresh fish is extremely perishable and is subject to bacterial spoilage. As fish spoils, its nutritional value decreases, as the bacteria causing the spoilage degrade the protein which is intended for human consumption. However, bacterial action produces nitrogenous compounds with noxious odours and the affected fish will become highly unattractive because there is too much nutritional damage. Bacterial spoilage in fresh fish can produce toxins which cause food poisoning; histamine contamination is prevalent among pelagic fish such as mackerel and sardine. Pathogenic bacterial contamination of fresh fish caused by poor handling and washing the fish in polluted water can also cause food poisoning. Traditional processing of cured fish frequently involves high temperatures, particularly when the fish is smoked or dried. It used to be thought that salting and drying effectively preserved the nutritional value of the original fresh fish and much of the older literature.
1.3 OBJECTIVES OF THE STUDY
The following are the objectives of this study:
1. To examine the method of prediction of the spoilage of fresh cured and dried tropical fish in Nigeria.
2. To examine the approaches for the control of the spoilage of fresh cured and dried tropical fish in Nigeria.
3. To identify the disadvantages of fish spoilage.
1.4 RESEARCH QUESTIONS
1. What is the method of prediction of the spoilage of fresh cured and dried tropical fish in Nigeria?
2. What are the approaches for the control of the spoilage of fresh cured and dried tropical fish in Nigeria?
3. What are the disadvantages of fish spoilage?
1.5 SIGNIFICANCE OF THE STUDY
The following are the significance of this study:
1. Finding from this study will educate on the method of prediction and control of the spoilage of fresh cured and dried tropical fish in Nigeria. The outcome of this study will also expose the factors causing spoilage in fish and the disadvantage of fish spoilage.
2. This research will be a contribution to the body of literature in the area of the effect of personality trait on student’s academic performance, thereby constituting the empirical literature for future research in the subject area.
1.6 SCOPE/LIMITATIONS OF THE STUDY
This study will cover the approaches into the prediction and control of the spoilage of fresh cured and dried tropical fish in Nigeria.
LIMITATION OF STUDY
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, questionnaire and interview).
Time constraint– The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.
Adebayo-Tayo AC; Odu NN; Michael MU;Okonko IO. 2012a. Multi-Drug Resistant (MDR) Organisms isolated from Sea-foods in Uyo, South-Southern Nigeria. Nature and Science; 10(3): 61-70.
Adebayo-Tayo BC, Odu NN, Okonko IO. 2012c. Microbiological and physiochemical changes and its correlation with quality indices of tilapia fish (Oreochromis niloticus) sold in Itu and Uyo markets in Akwa Ibom State, Nigeria. New York Science Journal;5(4):38-45
Okonko IO. 2012d. Microbiological and Physicochemical Level of Fresh Catfish (Arius hendelotic) From Different Markets in Akwa Ibom State, Nigeria. New York Science Journal;5(4):46- 52.
Adedeji O.B. 2012. Principal Human Disease Resulting From Ingestion or Contact With Fish and Shellfish. A Power Point Lecture Supplement in the Department of Veterinary Public Health & Preventive Medicine, Faculty of Veterinary Medicine, University of Ibadan, Nigeria.
Adedeji O. B. and Adetunji V.O. 2004. Pests in Farm Animals and Stored Animal Products. Agriculture, Renewable Natural Resources, Animal Husbandry and Health. Published by General Studies Programme (GSP) University of Ibadan. Nigeria. 141 – 151pp.