Effects of ozone wash for inactivation of S. typhimurium and background microbiota on lettuce and parsley

Experiments were done with ozonated water to evaluate its efficacy in reducing the numbers of Salmonella Typhimurium and total mesophilic aerobic bacteria (TMAB) on vegetables and in improving their storage quality. Ozonated water (0.5, 1.0 and 1.5ppm) treatment for 3, 5 and 10min caused reductions in the number of TMAB of lettuce and parsley samples ranging between 0.48-1.25 and 0.40-1.03log units, respectively. The counts of S. Typhimurium on inoculated lettuce samples were reduced by ozonated water in the range of 1.14-3.06 log units reductions, while 0.28-2.57 log units reductions were achieved for parsley samples. On the other hand, the effect of tap water in reducing TMAB and S. Typhimurium counts was found ranging between 0.10-1.20 and 0.44-0.60 log units, respectively. Reduction capacity of ozonated water (1.5ppm/5min) on microbial population was also tested in a school kitchen and results were similar with the laboratory findings (P>0.05). To determine the effects of ozonated water on the storage quality of the samples, TMAB and mold-yeast counts of vegetables were investigated during the storage period at 4C for 15 days. Results of the study showed that ozonated water is mainly useful for reducing S. Typhimurium cells from vegetables. © 2013 Wiley Periodicals, Inc