Meta-analysis of the effects of sanitizing treatments on Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes inactivation in fresh produce
The aim of this study was to perform a meta-analysis of the effects of sanitizing treatments of fresh produce on Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes. From 55 primary studies found to report on such effects, 40 were selected based on specific criteria, leading to more than 1000 data on mean log reduction of these three bacterial pathogens impairing the safety of fresh produce. Data were partitioned to build three meta-analytical models that could allow the assessment of differences in mean log reductions among pathogens, fresh produce and sanitizers. Moderating variables assessed in the meta-analytical models included type of fresh produce, type of sanitizer, concentration, treatment time and temperature. Further, a proposal was done to classify the sanitizers according to their bactericidal efficacy by means of a meta-analytical dendrogram. The results indicated that both time and temperature significantly affected the mean log reductions of the sanitizing treatment (p<0.0001). In general, sanitizer treatments led to lower mean log reductions when applied to leafy greens (for example, 0.68 log-reductions [0.00-1.37] achieved in lettuce) as compared to other non-leafy vegetables (for example, 3.04 mean log-reductions [2.32-3.76] obtained for carrots). Among the pathogens, E. coli 0157:H7 was more resistant to ozone (1.6 mean log reductions), while L. monocytogenes and Salmonella presented high resistance to organic acids such as, citric acid, acetic acid and lactic acid (∼3.0 mean log reductions). With regards to the sanitizers, it has been found that slightly acidic electrolysed water, acidified sodium chlorite and the gaseous chlorine dioxide clustered together, indicating they possessed the strongest bactericidal effect. The results reported seem to be an important achievement for advancing the global understanding of the effectiveness of sanitizers for microbial safety of fresh produce.
