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

Abstract

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.