Comparative assessment of microbiological safety of fresh and parboiled Engraulicypris sardella (Usipa) from selected selling points in the city of Mzuzu, Malawi

Abstract

This study assessed the microbiological safety of fresh and parboiled E. Sardella from selected selling points in the city of Mzuzu, Malawi. Samples were collected during the cold, dry and rainy seasons and the total plate count (TPC) was determined in CFU/g. The isolated colonies were sub cultured by streak method on selective and differential media to ascertain bacteria species. Bacteria species were subjected to confirmatory tests (gram-staining, carbohydrates, coagulase, catalase and indole) and motility tests. Counts of fresh samples were comparably higher than those of the parboiled samples during all the three seasons. During the cold season, the mean bacterial load of fresh E. Sardella was 2.26×105CFU/g and parboiled was 1.85×105CFU/g, records of dry season fresh samples yielded 1.50×105CFU/g and parboiled samples were 1.05×105CFU/g and finally, the rainy season fresh samples produced 2.41×105CFU/g and parboiled 1.86×105CFU/g. The bacteria species identified were: Proteus, Enterobacter, Klebsiella, Pseudomonas, E. coli, Enterococcus, Shigella, Salmonella, Staphylococcusaureus, Staphylococcusepidermis, Vibriocholerae and Vibrioparahaemolyticus. As expected, the moisture content influenced the growth of bacteria in fish: for fresh E. Sardella, it was 17.40±0.19%, 15.52±0.22% and 16.21±0.31% during cold, dry and rainy seasons respectively. Regarding parboiled samples, the moisture content was 10.43±0.03%, 9.55±0.38% and 9.36±0.99% for cold dry and rainy seasons, respectively. Statistically, the paired t- test showed significant differences in bacterial load among seasons and between treatments. It was observed that, the parboiling process reduced microbial load but poor hygiene, handling, storage and method of preservation influenced the load. Therefore, controlled temperatures, careful processing methods, proper storage and preservation are recommended to reduce incidence of microorganisms in fish