Effects of Smoking and Freezing on the Nutritive Value of African Mud Catfish, Clarias gariepinus Burchell, 1822

Post-harvest loss of fish is a major factor of economic and protein wastages in the developing countries. In this study, the effects of two common methods of preservation, smoking and freezing on the nutritive value of the African mud catfish, Clarias gariepinus were determined. Live samples of C. gariepinus were obtained from the fish farm of the Department of Environmental Biology and Fisheries, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria, and were transported to the laboratory of the Department. One portion of the harvested fish was smoked, using a smoking kiln (model- ELC 1600) at 60-70 oC for 24 hours and stored in a polythene bag for further use. Another batch of C. gariepinus was preserved immediately after harvest in the freezer (Haier Thermocool, BD-428A) at less than -0 oC for 20 days. The third batch of the live fish was sacrificed immediately and prepared for biochemical analysis. The proximate compositions of the fish samples were determined according to AOAC (1995). The percentage moisture, protein, lipid, ash, crude fibre and carbohydrate contents obtained in the smoked fish samples were statistically different (P > 0.05) to the fresh fish samples (control). Similarly, there were significant differences in the percentage protein, lipid and crude fibre values in the frozen fish samples when compared to the fresh fish samples but there were no significant changes (P < 0.05) in the moisture, ash and carbohydrate contents of the frozen fish samples in comparison to the control. The proximate values of the frozen fish evoked significant differences in comparison to the smoked samples except in the crude fibre and lipid contents. Phosphorous content was highest in the smoked fish samples and lowest in the fresh fish samples while the values of iron, potassium and vitamin C contents were generally low in all the samples. Smoking demonstrated a better efficient method of fish processing in terms of the retention of protein value and reduction in the moisture content. The information obtained in this study could be useful to fish consumers, processors and nutritionists in the efficient management of fish resources.