Efficacy of gaseous chlorine dioxide generated by sodium chlorite - carbon dioxide reaction on safety and quality of blueberries, cherry tomatoes, and grapes

This research evaluated the inactivation of Salmonella spp. and Listeria monocytogenes inoculated onto the calyces of blueberries, stem scars of cherry tomatoes, and surfaces of grapes using gaseous chlorine dioxide (ClO2) produced by the reaction between sodium chlorite (NaClO2) and carbon dioxide (CO2). The inoculated samples were treated with ClO2 gas in a treatment chamber for 3 h. The results suggested that the exposures of 366–477 ppm-h achieved 2.8 to 3.8, 2.4 to 4.3, and 3.8 to 6.4 log CFU/g in inactivation of both pathogens on blueberries, cherry tomatoes, and grapes, respectively. The inactivation of pathogens on grapes were significantly greater (p < 0.05) than those on blueberries and cherry tomatoes, likely due to the difference in the inoculation sites. During an 8-day post-treatment storage at 25 °C, the color attributes (L*, a*, and b*) of the fruit samples were not or little affected by either storage time or ClO2 treatment. The weight loss of treated and untreated samples during the storage was more affected by and increased with storage time, but it was higher in the untreated samples. The hardness was significantly affected by and decreased with storage time. It was higher in ClO2-treated blueberry and grape samples, but not in cherry tomato samples. The residual ClO2 on treated fruits, ranging from 0.08 to 0.35 mg/kg, was not affected by the storage time, but it was the highest in blueberry and the lowest in cherry tomato samples. These results clearly demonstrated that this method of gaseous ClO2 generation can be used to reduce pathogens on the fruit samples during postharvest intervention and storage, while improving product safety and quality.