Study on the Effect of Different Drying Methods on the Proximate, Nutritional and Mineral Composition of Clarias gariepinus (Catfish)

ABSTRACT

Aim: This study investigated the effect of modern drying methods on the proximate, nutritional, and mineral composition of Clarias gariepinus in Port Harcourt, Nigeria. Methods: Fresh C. gariepinus were purchased from Mile 3 Market in Port Harcourt, Rivers State. Samples were dissected using a sharp knife, intestinal components, and gills were removed and the edible portion was washed properly and rinsed with distilled water. Samples were treated in four groups fresh, smoking using firewood, electric drying (200oC), and non-electric drying (200oC for 30 minutes) methods. Samples were blended using mortar and pestle into powder and kept in an air-tight container prior to analyses. Results: The proximate composition of C. gariepinus revealed that crude protein concentration was in the following proportions; electric drying method (52.16+0.01%), non-electric drying method (43.40+0.00%), smoking method (32.72+0.00%) and fresh (23.01+0.00%). The lipid content of smoked and electric-dried C. gariepinus was significantly (p<0.05) higher compared to the fresh sample. However, there was no significant difference between the lipid content of fresh C. gariepinus sample and non-electric dried sample. The carbohydrate content increased in the smoking and electric drying methods but decreased in the non-electric drying method. The ash content increased only in the smoking method but decreased in both the electric dryer and non-electric dryer methods. Fresh samples had the highest moisture content (74.03+0.00%) while the least was observed in the electric dried sample (38.84+0.00%). The percent anti-nutrient composition of C. gariepinus showed that smoked samples had the highest flavonoid concentration (3.252±0.00%) which was not significantly higher (p>0.05) than the flavonoid content of electric dried C. gariepinus (2.89±0.33). The levels of selected minerals showed varying concentrations of potassium, sodium and calcium for the various processing methods. Conclusion: Modern drying methods had a significant effect on the proximate component, flavonoids, and oxalate composition of C. gariepinus. Electric drying method showed to be a better method of drying Clarias gariepinus compared to other drying methods.