Quality of fresh frozen tilapia from selected supermarkets in Malawi

Abstract

Fish provides a major source of dietary animal protein to Malawi’s population. Majority of tilapia in supermarkets are of different origins and bought from different suppliers. Fish is highly perishable commodity and its quality degrades even in frozen form due to microbial activity. The quality of frozen tilapia (the most commonly traded and consumed fish in Malawi) sold in some reputable supermarkets in Malawi was determined. Fish were collected from nine (9) reputable supermarkets in three (3) regions of the country (north, central and south) and analysed in the laboratory for sensory quality, microbiological, chemical and proximate analyses. Sensory quality evaluation was performed following guidelines earlier developed for fresh tilapia (Oreochromis spp.) in Malawi. Differences and changes in the fish sensory quality were attributed to the effect of storage duration and conditions within the freezer compartment. Two types of bacteria namely, Salmonella spp. and Escherichia coli
were identified on the frozen tilapia, suggesting poor and unhygienic pre-handling. Despite the presence of bacteria on the fish and differences in sensory quality, the frozen tilapia were within the acceptable range for human consumption. Nutrient composition of frozen tilapia was high despite differences (p<0.05) in moisture, ash and crude fat. Fish from different origin were sold mixed in all supermarkets, poor handling along the fish market chain was identified as the major source of fish contamination. Mechanical damages were reminiscent of the effects of frozen storage. There is a need to establish optimum storage time for frozen tilapia in supermarkets to provide products with good quality in terms of sensory properties, nutrient content and safe microbial loads.