Accumulation of Heavy Metal and Microbial Contamination of Smoked Catfish (Clarias gariepinus)
Abstract
Recently, over 70% of fish are smoked as a means of preservation. Smoking is an ancient processing method that remains widely practiced in Nigeria today. This study investigates the levels of heavy metal accumulation and microbial loads in smoked catfish obtained from two different catfish farms to determine the safety of smoked catfish sold in Owo during the research period. Samples were collected from two farms (Farm 1 and Farm 2) in Owo, located in Owo Local Government Area, Ondo State, Nigeria. The identified microorganisms included Streptococcus spp., Staphylococcus aureus, Bacillus spp., Klebsiella spp., Pseudomonas aeruginosa, and Escherichia coli. The microbial counts for samples A and B were as follows: Streptococcus spp. (90.0 and 60.0), Staphylococcus aureus (160.0 and 170.0), Bacillus spp. (230.0 and 215.0), Klebsiella spp. (110.0 and 120.0), Pseudomonas aeruginosa (15.0 and 10.0), and Escherichia coli (2.0 and 1.0). For heavy metals, the concentrations were Cu (0.001 and 0.000), Cd (0.222 and 0.002), Cr (0.840 and 0.670), Mn (2.33 and 1.99), and Zn (132.020 and 127.001). The highest microbial count was observed in Bacillus spp. from Sample A (230.0) and Sample B (215.0), while the lowest was found in Escherichia coli from Sample B (1.0) and Sample A (2.0). Among the heavy metals, zinc was the most abundant in both samples, with Sample A (132.020) having a higher concentration than Sample B (127.001). Copper was the least abundant, being almost undetectable in Sample A (0.001) and entirely undetectable in Sample B (0.000). The study revealed variations in microbial and heavy metal contamination levels between catfish farms. It highlights the need for regulatory authorities to enforce moisture control measures and implement strategies to reduce human activities that may lead to bacterial growth and heavy metal contamination in smoked catfish products.