Ozone application for inactivation of Escherichia coli in air-conditioned environments for food production
Abstract
Air quality in food production environments requires strict control to maintain product quality and safety. This study aimed to investigate the Escherichia coli inactivation pattern through the application of gaseous ozone in a pilot-scale ozonation chamber. The methodology consisted of simulating the gas distribution in the ozonation chamber using computational fluid dynamics to identify regions for better positioning of plates containing E. coli for inactivation tests. Inoculation of E. coli ATCC 25,922 in plate count agar and exposure in the ozonation chamber were performed. The inactivation of E. coli was evaluated by applying ozone for 15, 30, 45, 60, and 120 min. Three kinetic models (linear, biphasic, Weibull) were fitted to experimental data to understand the inactivation pattern of this microorganism. The simulation identified the best position for the plates with E. coli, at a height of 0.45 m above the floor. The concentration of E. coli was reduced by at least 90% (1.0 log₁₀ reduction) after 30 min of ozonation, reaching a maximum of 99.98% (3.7 log₁₀ reduction) for the highest inoculum concentration tested. The kinetic study revealed that the inactivation pattern was better described by a biphasic model, suggesting variations in the resistance of bacteria to the treatment of ozone decontamination.
