Effect of Different Preservative Methods on Microbiological, Nutritional and Mineral Contents of Selected Fish from Major Urban Markets in Benin City, Nigeria

Abstract

The effect of different preservative methods gas dried, wood smoked and frozen on different fish species (Merluccius merluccius, Scomber scombrus and Trachurus trachurus obtained from different markets within Benin metropolis were investigated. Thirty Six fish samples were analyzed using standard culture-based and spectroscopic methods. The wood-smoked method for Merluccius merluccius revealed the highest microbial load of 6.32×10⁷±0.42 cfu/g and 2.05×10⁷±0.14 cfu/g for bacterial and fungal densities respectively. Frozen and gas-dried methods had the lowest microbial load of 2.2×10⁶±1.56 cfu/g and 2.70×10⁷ ±0.17 cfu/g of bacterial densities and 4.3×10⁶ ±0.02 cfu/g and3.3×10⁶ ±0.01cfu/g of fungal densities respectively. The microbial isolates include Bacillus spp., Staphylococcus aureus, Pseudomonas aeruginosa, Micrococcus spp., Corynebacteria spp., Escherichia coli, Streptococcus spp., and Proteus spp., The proximate analyses revealed as follows - proteins (12.31 - 23.04%); lipid (7.63 - 37.55%); ash (9.49 - 14.28%), fiber (0.63 - 2.31%) and carbohydrate contents (29.0 - 63.47%). The macro and micro elements constituents revealed that the fish contain significant amount of nitrogen (0.07±0.01-3.69±0.05 mg/100g DWB); phosphorus (0.08±0.03-0.28±0.01mg/100g DWB); potassium (0.09±0.04-0.50±0.01 mg/100g DWB); calcium (0.07±0.01-1.06±0.02 mg/100g DWB); and magnesium (0.05±0.01 - 0.09±0.01 mg/100g DWB). The presence of potential pathogenic microbes from the study revealed that the fish as well as method of processing are of immense public health concerns.