Effect of Chlorine Dioxide Gas onSalmonella entericaInoculated on Navel Orange Surfaces and Its Impact on the Quality Attributes of Treated Oranges

Abstract

Microorganisms, including pathogens of public health significance, have been shown to contaminate orange juice during the mechanical extraction of juice. The problem gets exacerbated when washed oranges have high initial microbial load, due to an insufficient postharvest treatment. The objective of this study was to investigate the reduction of Salmonella enterica on orange surfaces using ClO₂ gas treatments to achieve a 5 log reduction, consistent with the recommendations of the U.S. Department of Agriculture-National Advisory Committee on Microbiological Criteria for Foods. A mixed culture of four Salmonella strains, isolated from previous orange juice outbreaks, was spot inoculated onto orange skin surface areas. The oranges were then treated with 0.1, 0.3, and 0.5 mg/L ClO₂ gas for 2-14 minutes at 22°C and 90%-95% relative humidity. Surviving bacteria on treated areas were recovered and enumerated over treatment time on a nonselective medium, tryptic soy agar, followed by culturing onto a selective medium, xylose lysine deoxycholate agar. A >5 log reduction of Salmonella per sample of orange surface was observed with 0.1 and 0.3 mg/L ClO₂ gas treatments at 14 minutes and a similar log reduction was observed at 0.5 mg/L ClO₂ gas at 10 minutes. This result demonstrates that the treatment of oranges with ClO₂ gas is a promising technology that could be successfully employed for the treatment of whole oranges to reduce the risk of Salmonella outbreaks in orange juice.

Antimicrobial efficacy of gaseous chlorine dioxide against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum)

“…The result is in agreement with the study conducted by Bhagat et al . () on vapour‐phase decontamination (0.1–0.5 mg L −1 for 2–14 min) of S. enterica on navel orange surface, as well as with the study conducted by Trinetta et al . () on using high‐concentration‐short‐time ClO 2 gas treatment (2.0–10.0 mg L −1 for 10–180 s) to inactivate S. enterica spp.…”

“…The linear effects of both parameters, shown in Table 3 (for details of model fitting, see section Model fitting and validation), are positive, that is the population reduction increased as the ClO 2 gas level increased or treatment time lengthened. The result is in agreement with the study conducted by Bhagat et al (2011) on vapour-phase decontamination (0.1-0.5 mg L À1 for 2-14 min) of S. enterica on navel orange surface, as well as with the study conducted by Trinetta et al (2010) on using high-concentration-short-time ClO 2 gas treatment (2.0-10.0 mg L À1 for 10-180 s) to inactivate S. enterica spp. on Roma tomato surface, suggesting potential uses of gaseous ClO 2 for a commercial fumigation of some fruits and/or vegetables before packing.…”

Gaseous Decontamination Methods in High-containment Laboratories

“…Many studies have found GCD effective against food-borne pathogens such as Escherichia coli, Listeria monocytogenes, and Salmonella enterica in applications in the food-processing industry (Bhagat et al, 2011;Bhagat et al, 2010;Mahmoud et al, 2007;Mahmoud et al, 2008;Trinetta et al, 2010). GCD has also been proven effective against viruses even at relatively low concentrations with extended exposure times (Morino et al, 2009;Sanekata et al, 2010).…”

Effect of the Use of a Neutralizing Step after Antimicrobial Application on Microbial Counts during Challenge Studies for Orange Disinfection

“…The inclusion of a neutralizing step after contact with the antimicrobial, although previously recommended, is not a standard practice among researchers and varies among studies (4,10,11,15,19). Collins-Thompson and Jackson (8) recommended the use of ice-cold water to arrest any residual effects of heat exposure in order to gain accurate estimates of heating effects on microbial survival and death.…”