Effect of Chlorine on the Survival of Vibrio cholerae on Shrimp

Abstract

Shrimp is a an important commodity in international trade and stringent quality parameters stipulates zero tolerance of Vibrio choleare in the imported commodity. Sanitary requirements for production of good quality shrimp for processing and export stipulates that shrimp tissue is to decontaminated frompathogens like Vibrio cholerae by washingwith potable water carrying chlorine .Hence effective dose of chlorine to be used in the process water is very critical. The present study was aimed at assessing the microbicidal efficacy of chlorine against Vibrio cholerae cells in water and shrimp with and without shell. The study indicated that in potable water with 2ppm residual chlorine level, a population of 10 7 cfu of Vibrio cholerae could be destroyed after 30 min exposure. Studies on shrimp meat contaminated with varying levels of Vibrio cholerae exposed to chlorine showed that 4ppm chlorine could effect complete destruction of a population of 103 cfu /ml in lOmin. On headless shrimp with shellon, 7ppm chlorine was required to destroy 103 cells /g of V.cholerae within 10 min. The data indicate that chlorine level has to be adjusted depending on nature of material and Vibrio cholerae present in shell-on shrimp need special attention.