Microbial quality assessment of omena (Rastrineobola argentea) sourced from schools, warehouses, and markets in Murang’a, Makueni, Nairobi, and Homabay

Abstract

Omena (Rastrineobola argentea)) is an important fish species in Lake Victoria. It is a significant protein source for consumers in Kenya. However, poor handling of omena poses quality and safety concerns. This study evaluated the microbial quality of omena sourced from four counties in Kenya. Purposive sampling was employed to collect samples from selected schools, warehouses, and marketplaces in Homabay, Muranga, Nairobi and Makueni counties. The Association of Official Analytical Chemists (AOAC 2000) procedures were used to detect Staphylococcus aures, Escherichia coli, and Salmonella spp. in sun-dried, stewed and deep-fried omena. The total viable counts in sun dried, stewed, and deep-fried omena ranges were log 5.5 to 7.9 CFU/g, 0 to log 3.77 CFU/g, and log 7.766 to 7.768 CFU/g, respectively. Escherichia coli in sun-dried, stewed, and deep-fried omena ranged from 0 to log 4.4 CFU/g, 0 to log 1.6 CFU/g, and 0 to log 5.3 CFU/g, respectively. Staphylococcus in sun-dried, stewed, and deep-fried omena varied from log 3.9 to 6.9 CFU/g, 0 to log 1.2 CFU/g, and log 4.6 to 5.3 CFU/g, respectively. The standard levels for cooked omena are 0 for Escherichia coli, and Staphylococcus count and log ≤ 4 CFU/g for total viable count. Prevalence of Salmonella typhimurium in omena from warehouses, and marketplaces was 34% and 50%, respectively. None of the samples contained Salmonella typhi. Shigella flexneri was at 14% and 25% in schools and market places respectively. Microbiological quality in most sun dried, and deep-fried omena samples was above critical limit, suggesting potential lapses in sanitation and unsafe handling practices of the omena. Stewed omena samples were mostly below critical limit and therefore safe for consumption.