Effects of Smoking Duration on the Proximate and Mineral Composition of Selected Fishes from Lower River Benue, Benue State, Nigeria

The proximate and mineral compositions of selected smoked fish species from the open market were compared to samples smoked for 4 hours, 6 hours and 8 hours. Clarias gariepinus, Synodonthes schall and Lates niloticus randomly sampled from fishermen catches at Lower River Benue were smoked at 70OC – 80OC temperature using mud type kiln and Prosopis africana as the energy source. The chemical analyses were done using the standard methods. Significant differences (P<0.05) was observed in all the parameters examined between all the species and treatments. Clarias gariepinus had the highest (50.80±1.26) protein content while Lates niloticus was least (40.79±0.81). Also, Clarias gariepinus was highest (7.13±0.39) in Lipids content and Lates niloticus, lowest (4.34±0.12). Smoking duration had inverse impact on moisture content (7.44±0.01 - 5.22±0.01) and direct impact on protein content (47.46±0.01 - 54.33±0.01). Lipid was observed to be lowest (6.33±0.01) in the 4-hour smoked sample and highest (8.33±0.01) in the 8-hour smoked Clarias gariepinus. Clarias gariepinus had higher mineral content than other species with reference to Calcium, Potassium, Iron, Magnesium, Sodium, Zinc and Copper. However, the duration of smoking was observed to have a negative impact on the potassium content of the fish samples while other examined minerals showed positive correlation. It is thus concluded that Clarias gariepinus is more nutritious than Synodonthes schall and Lates niloticus from Lower River Benue and better when smoked for 6 hours. Also, it could be inferred that smoked fish sold in the open market are mostly smoked for 6 hours. However, 8-hour smoking duration is recommended for a prolonged shelf life with consideration for nutrient-specific smoking duration especially when the need for specific micro nutrients is of interest.