Development of sustained release formulations of chlorine dioxide gas for inactivation of foodborne pathogens on produce

Formulations for the sustained release of chlorine dioxide (ClO₂) gas were developed, and their gas-producing profiles and antimicrobial effects against Escherichia coli O157:H7 and Salmonella Typhimurium were evaluated in spinach leaves and tomatoes under different relative humidity (RH) conditions. Sodium chlorite (NaClO₂) and citric acid were used to generate ClO₂ gas, and the generation rate and maximum ClO₂ gas concentration were controlled using diatomaceous earth (DE) and calcium chloride (CaCl₂). Under 90% RH conditions, sustained release of ClO₂ gas was achieved in presence of DE. When 12 g of DE was added to the mixture, the ClO₂ gas concentration remained constant at 18 ± 1 ppmv for approximately 28 h. At 50% RH, addition of CaCl₂ was effective in maintaining a constant ClO₂ gas concentration. When 0.05 g of CaCl₂ was added to mixtures containing 0.5 g of DE, ClO₂ gas concentration remained constant at 11 ± 1 ppmv for approximately 26 h. Treatment with 30 ppmv of ClO₂ gas at 90% RH achieved more than 6.16 and 5.48 log reductions of E. coli O157:H7 and S. Typhimurium on spinach leaves (in 15 min), and more than 6.78 and 6.34 log reductions of the same in tomatoes (in 10 min). The sustained release formulations for ClO₂ gas, developed in this study, could facilitate the use of ClO₂ gas as an antimicrobial agent in the food industry.