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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #360677

Research Project: Ecology and Detection of Human Pathogens in the Produce Production Continuum

Location: Produce Safety and Microbiology Research

Title: Identifying nonpathogenic Salmonella surrogates for industrial scale treatment of almonds using gaseous chlorine dioxide

item RANE, BHARGAVI - Washington State University
item Lacombe, Alison
item SABLANI, SHYAM - Washington State University
item Bridges, David
item TANG, JUMING - Washington State University
item GUAN, JIEWEN - Washington State University
item Wu, Vivian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In order to conduct successful challenge studies in industrial facilities, non-pathogenic surrogates are used to represent the target pathogens. Enterococcus faecium is the most commonly used and approved surrogate for Salmonella enterica in almond processing. This study would help fill up the research gap of E. faecium as a surrogate for gaseous ClO2 treatment on almonds. The objective of this study was to evaluate the potential of surrogate strain to represent pathogenic Salmonella during gaseous chlorine dioxide (ClO2) treatments. Cocktail of five pathogenic Salmonella strains, and E. faecium NRRL B-2354 were used separately to inoculate 200 g of almonds. Gaseous ClO2 was generated on site using dry precursors by mixing sodium chlorite and activating acid. Treatments were conducted at various concentrations (0.4, 0.5, and 0.6 mg of ClO2/g of almonds) and exposure times (2, 3, and 4 h) in a circulatory system made of PVC pipes with an attached fan blowing the gas (dry precursor mix method) towards the inoculated almonds. The log reductions of Salmonella demonstrated the same trend as in E. faecium, which established its potential as a suitable surrogate for ClO2 studies. Throughout the entire treatment, held at different concentrations and exposure times, the difference in log reductions between Salmonella and E. faecium was in the range of 0.01 to 0.71 log CFU/g. This indicates E. faecium to be a robust surrogate for validating ClO2 treatments. Kinetic modeling inferred that the reduction trend was linear with respect to treatment concentrations. E. faecium is a suitable surrogate and will be used to scale up the ClO2 treatment in the almond industry to avoid cross-contamination in the facility.