Microbiological Quality Of Raw And Processed Farm-Reared Periwinkles From Brackish Water Earthen Pond Buguma, Nigeria

The microbiological quality of raw and processed periwinkles obtained from brackish water earthen pond of the African Regional Aquaculture Centre, Buguma, Rivers State, Nigeria was studied. The samples were harvested at exactly 11 am on a Monday morning, at high tide and water temperature of about 29°C. Ninety samples were analyzed and used for the study, which comprised the enumeration of indicator organisms and other pathogens as well as their total counts. Total bacterial counts of the samples from boiled periwinkle meat, boiled shell-on periwinkles and raw periwinkle meat were <10, 2.32 – 2.41 x 10⁶, and 1.65 – 1.86 x 10^6- cfu/g, respectively. The boiled shell-on periwinkle sample had the highest level of microbial growth. The result of these microbiological examinations of boiled shell-on, raw and boiled periwinkle meat (without shell) showed that the boiled shell-on and raw periwinkle meat contained unacceptable levels of bacteria with a mean total bacterial count of 2.37 x 10⁶ and 1.77 x 10⁶ cfu/g, respectively. On the contrary the processed (boiled) periwinkle meat contained a total plate count of <10 cfu/g. The organisms isolated from all the periwinkle samples included Salmonella paratyphi, Escherichia coli, Proteus vulgaris, Aerobacter aerogenes, Pseudomonas aeruginosa, Staphylococcus aureus, Erwinia amylovora and Serratia maracescense. Indicator organisms especially Salmonella paratyphi and Aerobacter aerogenes seemed to be more common in the isolated samples with the highest number among the isolated bacteria especially in the boiled shell-on periwinkle and raw periwinkle meat. Some psychotropic organisms such as Erwinia amylovora and Serratia maracescense were also isolated although Serratia maracescence and Proteus vulgaris were the least encountered in all the samples analysed. The fungi isolated from raw periwinkle were Fusarium species and Sacharomyces cerevisiae with a fungi load of <10 cfu/g for both samples. There was no record of any fungal load in the boiled periwinkle meat. The isolation of indicator organisms as well as other pathogens from the boiled shell on periwinkles and raw periwinkle meat should be a source of concern to the consumers especially in South/South Nigeria where they are mostly cooked with the shell on, or inadequately cooked because of some perceived medical and nutritive values.