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.

Assessment of bio-accumulation of bacteria in oysters from shellfish growing waters in Ashtamudi Lake (Kerala, India): A RAMSAR wetland

“…This requires depuration or relaying to an 'A' category area over a period of time to meet health standards prior to human consumption according to current EU regulations (EC, 2004a). This is in agreement with many of the previous studies from India (Raveendran et al, 1990;Lalitha and Surendran, 2004;Sasikumar and Krishnamoorthy, 2010;Hassan et al, 2013). Recent study by Chinnadurai et al (2014) showed that Indian back water oysters accumulated bacterial loads above the threshold limits during the winter monsoon and they demonstrated the depuration of oysters to reduce FC and E.coli to safe levels can be accomplished within 24 h.…”

“…Similarly, shellfish such as clams harvested from Vembanad Lake (Kerala) north of Ashtamudi Lake are reported to have high levels of faecal coliforms and E. coli (Lalitha and Surendran, 2004;Hassan et al, 2013). This may be because these two lakes are situated close to the major cities of Kerala and are interconnected with the canals of the cities that discharge sewage into the lakes.…”

Recent Advances in Drying Processing Technologies for Aquatic Products

“…The drying process can remove moisture from aquatic products, reducing their moisture content and inhibiting the proliferation and growth of bacteria. Additionally, heat treatment can disrupt the cellular structure of aquatic products, or processes such as VFD at extremely low temperatures can decrease bacterial activity, thereby reducing bacterial load, extending the shelf life of aquatic products, and preserving their sensory and biochemical attributes [120]. Currently, total viable count is commonly used as an indicator to evaluate the microbial content of seafood products in the food industry.…”

A systematic review of drying in aquatic products

“…These products whose total number of colonies is below 5 × 10 5 CFU/g are good; those from 5 × 10 5 to 10 7 CFU/g are moderately acceptable; and those at or above 10 7 are considered unacceptable 125 . The drying process prevents bacteria from multiplying by removing moisture, destroys the structure of bacteria by heat processing or reduces the activity of bacteria by extremely low temperatures like FD 126 . However, there was nearly no literature about the dynamic monitoring of microorganisms during the drying process.…”

“…125 The drying process prevents bacteria from multiplying by removing moisture, destroys the structure of bacteria by heat processing or reduces the activity of bacteria by extremely low temperatures like FD. 126 However, there was nearly no literature about the dynamic monitoring of microorganisms during the drying process. Most studies focused on the storage ability of dried aquatic products.…”