Effect of smoking and sun drying on proximate composition of Diplotaxodon fish species (Ndunduma) from lake Malawi, Malawi

Abstract

Processed fish and fish products have high nutritional value, longer shelf life and fetch better prices on the market in contrast to freshly caught fish which are highly perishable. Processing, however, alters nutrient composition of a product underpinning the need for caution when consuming processed products. The study analyzed the effect of traditional smoking and sun drying on proximate composition (moisture, protein, fat and ash) of Diplotaxodon species locally known as Ndunduma. This is an important commercial cichlid species harvested across the entire Lake Malawi by both artisanal and commercial fishers. Fresh  Diplotaxodon fish samples were collected from fishers’ boats in the southwestern part of Lake Malawi, Malawi immediately after catch early in the morning. The fish were washed then weighed and thereafter, smoked in a traditional smoking kiln and sun dried on reed mats.  Determined percent moisture, protein, fat and ash content for smoked fish were: 12.22±0.05, 55.30±1.67, 25.31±2.78 and 12.96±0.72, respectively, while corresponding values for fish that were sun dried were: 24.28±0.14,  52.80±1.28, 22.36±0.26 and 13.81±0.14, respectively. Overall, results show reduced protein content in processed fish (smoked and sun dried) (P<0.05) although not significantly different in smoked fish (P>0.05). Significantly low moisture content in smoked fish is indicative of a product with longer shelf life since moisture favours rapid microbial growth causing freshness quality deterioration. Although not  significantly different, high fat (P>0.05) and ash (P<0.05) in smoked fish is  consistent with a nutrient rich product. The study concludes that smoked   Diplotaxodon species is more nutritious and may present better storage qualities than sun dried due to relatively low moisture. Caution should, nevertheless, be considered due to the high fat levels to prevent spoilage caused by breakdown of fats. Since smoked products are of high commercial value, fish processors should be encouraged to smoke fresh Diplotaxodon species other than sun drying.

Key words: Diplotaxodon species, Ndunduma, processing, proximate composition, Lake Malawi