Efficacy of gaseous ozone for reducing microflora and foodborne pathogens on button mushroom

• Efficacy of ozonation for the microbial reduction on button mushroom was evaluated.
• Fates of Salmonella, L. monocytogenes and E. coli O157:H7 were also evaluated.
• Ozonation performed at the concentrations of 2.8 and 5.3 mg L−1 for up to 60 min.
• Ozonation for 60 min yielded up to 3.07 log reduction in the aerobic plate counts.
• Ozonation for 60 min yielded up to 3.61 log reduction in the pathogen counts.

During growth, mushrooms can be contaminated with both saprophytic and pathogenic microorganisms derived from various points of contamination. This study was performed to evaluate the efficacy of gaseous ozone for reduction of microbial load and elimination of Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 on white button mushroom (Agaricus bisporus (J.E. Lange) Imbach). Whole mushroom samples were exposed to gaseous ozone up to 60 min at concentrations of 2.8 and 5.3 mg L−1. The level of yeast and mold population naturally present on mushrooms was reduced more than 1.43 log after ozonation at 5.3 mg L−1 for 45 min. Exposure to ozone at 2.8 and 5.3 mg L−1 for 60 min yielded 2.44 and 3.07 log reductions in aerobic plate counts, respectively. Initial levels of Salmonella, L. monocytogenes and E. coli O157:H7 populations on inoculated mushrooms reduced by ranging 2.10 and 2.76 log after 60 min of treatment performed at concentration of 2.8 mg L−1, respectively. Ozonation at 5.3 mg L−1 for 60 min reduced the initial counts of Salmonella, L. monocytogenes and E. coli O157:H7 by 3.61, 2.80 and over 3.41 log, respectively. These results suggest that gaseous ozone treatment can improve the microbial safety and postharvest quality of mushrooms.