Combined effect of lime (Citrus aurantitolia) and drying on reducing bacteria of public health significance in Edible Oyster (Crassostrea madrasensis)

Abstract

Combined effect of lime and drying on bacteria of public health significance in Edible Oyster (Crassostrea madrasensis) from Munambam coastal belt (Kerala, India) were studied (without depuration). Samples were examined for Total Plate Count (TPC), Staphylococcus aureus (hygiene indicator), Total coliforms, Faecal coliforms, Escherichia coli, (faecal indicator) Faecal Streptococci (faecal indicator), Salmonella, Vibrio cholera and Listeria monocytogenes. The fresh oyster meat though did not confirm to the specifications laid by National shellfish sanitation programme (NSSP), after treatment with lime with and without drying found to show significant reduction in counts and meet the required standards. Prevalence of faecal indicators in the fresh sample indicated faecal pollution in the area. The isolation of potentially pathogenic bacteria, V. parahaemolyticus in fresh sample indicates high risk of people consuming and handling oysters in raw and semi processed form and also it may lead to cross contamination. The present study indicates that treatment with natural organic product like lime and simple preservation technique, drying can effectively reduce the bacterial load. The study also revealed that TPC of water and soil collected from the site from where oysters were collected was less than from the meat.