Validation of thiosulfate for neutralization of acidified sodium chlorite in microbiological testing

At low pH, acidified sodium chlorite (ASC) has antimicrobial activity again st a variety of foodborne contaminants. To evaluate the antimicrobial effic acy of ASC at specific time points posttreatment, it is necessary to halt t he action of the disinfectant by removing residual chlorite or by increasin g the pH. In this study, thiosulfate was investigated at varying concentrat ions for its effect on microbial survival and was investigated at a concent ration of 0.1% in the presence of ASC for its effect on the antimicrobial a nd chemical activity of the test solution. Additionally, sodium thiosulfate was tested in two buffering systems, buffered peptone water (BPW) and Butt erfield's phopshate buffer (BPB), for its ability to inactivate ASC chemist ry. The results of this study show that, at a concentration of 0.1%, sodium thi osulfate has no deleterious effect on Escherichia roll survival and is effe ctive in halting the antimicrobial action of ASC by eliminating the product ion of residual chlorite. The BPW alone and BPB in combination with thiosul fate were found to be effective inactivators of ASC chemistry.