Microbial quality and safety of fresh and dried Rastrineobola argentea from Lake Victoria, Tanzania

Abstract

Rastrineobola argentea (silver cyprinid/sardines) is an important commercial fish species found in Lake Victoria. It is an important protein source for consumers in several African countries including Tanzania. A cross-sectional study was conducted using standard methods to assess the bacteriological quality of fresh and dried sardines from Lake Victoria. Sardine samples were randomly collected from main landing sites and retail markets in the city of Mwanza. Total viable counts (TVC) in fresh sardines were in the range of 5.18–7.90 log10 cfu/g while those dried on racks contained 3.13–4.85 log10 cfu/g which were 0.75% of those dried on sand with 4.80–7.13 log10 cfu/g (p < 0.001, 95% CL: 0.40%–1.42%). Thus, rack dried sardines had mean TVC below the national acceptable food standard of 5 log10 cfu/g. Faecal contamination with E. coli in fresh sardines ranged from 2.38 to 5.38 log10 mpn/g and those dried on sand contained 1.18–3.32 log10 mpn/g, however, sardines dried on racks, did not contain any E. coli. Similar findings were found in the two types of dried sardines from the retail markets. Prevalence of Salmonella spp. in fresh R. argentea was 25% (n = 40), sand dried sardines at landing sites contained 30% (n = 20) and those from the markets contained 15% (n = 20) Salmonella spp. Salmonella spp. were not detected in sardines dried on racks. To conclude, sun drying of sardines on racks is an effective drying method providing a safe product for human consumption.