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.