Nutritional composition of smoked and sun dried pond raised oreochromis karongae (Trewavas, 1941) and tilapia rendalli (Boulenger, 1896)

Abstract

A study was carried out to determine nutritional composition of two pond raised tilapia fish species - Oreochromis karongae (Lake Malawi Tilapia) and Tilapia rendalli processed by smoking and sun drying. These are two of the four tilapia species (others are Oreochromis mossambicus and Oreochromis shiranus) that are raised in pond aquaculture in Malawi. Presenting pond raised fish in processed form would help farmers realise more economic benefits because processed products fetch better market prices. Results showed that both fish species are highly nutritious with high levels of the much needed dietary protein (fresh/unprocessed) 63.14±0.19 and 62.92±0.16 for O. karongae and T. rendalli respectively. However, protein content was significantly reduced (P<0.05) when both species were smoked - O. karongae (61.48±0.19) and T. rendalli (61.82±0.10). With an exception of ash for O. karongae, the other nutrients were also reduced in smoked fish in both species. Smoking therefore negatively affected the nutrient content of the fish. Protein and moisture content in O. karongae decreased (62.60±0.27; 8.33±0.33 respectively) with sun drying, while fat increased (11.67±0.88) and there were no changes in ash content (20.00±0.00) and vice versa in T. rendalli (63.26±0.13) (P<0.05). In sun dried T. rendalli, protein and fat content increased (P<0.05) (63.16±0.13 and 15.27±1.22 respectively) while a decrease was observed in ash and moisture levels (P<0.05) (20.00±0.00 and 7.67±0.33 respectively). Despite increasing fat content in both species, results demonstrated that a sun dried product was superior because of high protein retention hence more nutritious and comparatively low moisture suggesting a longer storage life.