ABSTRACT
The microbial load on smoked fish sold in Ibadan, Oyo State was studied. 64 of 4 different fish species (Mackerel (Scomberscombrus), Sardine (Sardinelaeba), Panla (Gadusmorhua) and Cat fish (Clariasgariepinus)) were sourced from five different market locations. The microbiological analysis was done using standard microbiological procedures. The bacterial count of fish sampled from Ojo market was the highest (0.35±0.11 x 103 CFU/g) while the bacteria count of the fish sample from Bodija market was the lowest (0.07±0.04 x 103 CFU/g). There was no significant difference (p>0.05) in the microbial load of the various fish species sold within Ibadan metropolis as well as fish sampled from various market locations in Ibadan metropolis. Bacterial isolated on smoked fish studied were: E. coli, Salmonella spp, Klebsiella spp, Staphylococcus aureus, Aerosomonas spp, Pseudomonas spp, Vibrio spp, Serratia spp, Chromobacterium spp, Enterobacteria spp and Shigella spp. While the following fungi were isolated from the study: Aspergillus flavus, Penicillium spp, Fusarium oxysporum, Trrichoderma spp and Ceotrichium albidium. Fish species sold in different markets within Ibadan metropolis is fit for human consumption. Caution should be exercised in consuming smoked-dried fish displayed openly, reheating may be necessary to activate such micro-organisms before consumption.
CHAPTER ONE
INTRODUCTION
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. It is known that the primary source of cholera is feces of infected persons and transmission of bacteria with water and food. However, at present it has also been found that in certain areas the aquatic environment is a natural reservoir (habitat) for Vibriocholerae. Microbiologists are of the opinion that the presence of Escherichia coli in food indicates the probability of contamination of the food products with the sewage of human or animal origin (Ofred, 2009). Data on risk factors for foodborne diseases indicate that the majority of outbreaks result from inappropriate food handling practices (Jones and Angulo, 2006). Incidences of food borne disease outbreaks are been reported each year in Kenya (Githiri et al., 2009). However, there is scarcity of information on occurrences of pathogens on fish and other ready to eat food in Nigeria thus the need for this study.
1.2 Aim and Objectives
The objective of the study is to determine some microorganisms that are prevalent on smoked fish sold in markets in Ibadan Oyo State Nigeria.