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

Abstract

At low pH, acidified sodium chlorite (ASC) has antimicrobial activity against a variety of foodborne contaminants. To evaluate the antimicrobial efficacy of ASC at specific time points posttreatment, it is necessary to halt the action of the disinfectant by removing residual chlorite or by increasing the pH. In this study, thiosulfate was investigated at varying concentrations for its effect on microbial survival and was investigated at a concentration of 0.1% in the presence of ASC for its effect on the antimicrobial and chemical activity of the test solution. Additionally, sodium thiosulfate was tested in two buffering systems, buffered peptone water (BPW) and Butterfield's phopshate buffer (BPB), for its ability to inactivate ASC chemistry. The results of this study show that, at a concentration of 0.1%, sodium thiosulfate has no deleterious effect on Escherichia coli survival and is effective in halting the antimicrobial action of ASC by eliminating the production of residual chlorite. The BPW alone and BPB in combination with thiosulfate were found to be effective inactivators of ASC chemistry.

Comparable levels of microbial contamination in soil and on tomato crops after drip irrigation with treated wastewater or potable water

“…For indicator bacteria and chemical parameter testing, one liter of each water type was collected in sterilized Nalgene bottles (Rochester, NY) containing sodium thiosulfate (0.1% v/v, Sigma, New Orleans, MO) to neutralize chlorine (Kemp and Schneider, 2000). The water was transported to the laboratory on ice, stored in 4 • C and analyzed within 24 h. For pathogen detection, one hundred liters of the treated effluents and potable water were collected in four 25-L jerricans and transported to the laboratory.…”

A pilot plant scale evaluation of a new process aid for enhancing chlorine efficacy against pathogen survival and cross-contamination during produce wash

“…The water samples collected from the wash tank for microbial testing were immediately poured into filter (to remove debris) bags containing sodium thiosulfate to neutralize the residual chlorine (Kemp and Schneider, 2000). Duplicate 25-g samples of lettuce from each sampling point were weighed into sterile, filter bags (WhirlPak®, Nasco, Modesto, CA) and macerated with 125 ml of sterile TSB at 230 rpm for 2 min with a stomacher blender (Seward Stomacher 400, London, UK).…”

Application of water-assisted ultraviolet light processing on the inactivation of murine norovirus on blueberries

“…To determine the survival virus in the spent wash water, 9 mL of the wash water was taken immediately after treatments without chlorine and mixed with 1 mL of PBS (10 ×, pH 7.2) (Kerafast, Inc., Boston, MA, USA) and the mixture was used for viral plaque assays. For chlorinated water treatment, wash water was mixed with an equal volume of 0.1% sterile sodium thiosulfate (Sigma-Aldrich, USA) to neutralize the residual chlorine (Kemp and Schneider, 2000) and 9 mL of the mixture was added to 1 mL of PBS (10 ×, pH 7.2) (Kerafast, Inc.) before plaque assay. The detection limit was 1 PFU/mL of wash water.…”