Purpose: The objective of this study was to summarize the effect of sanitizers on the mean log-reduction of E. coli O157:H7 on fresh produce, and to explain between-study variability by incorporating study characteristics (type of produce, sanitizer, concentration, treatment time and temperature) to a mixed-effects meta-analysis model.
Methods: After the extraction of log-reduction values, sample size and study characteristics from the 40 primary studies considered appropriate for meta-analysis, a mixed-effects linear model was fitted to the data, considering mean log-reduction as the response variable, type of sanitizer, sanitizer concentration, temperature and time as the fixed-effects explanatory variables, and the interaction study×produce as subject of the random effects.
Results: For most of the sanitizers, the meta-analysis model showed that the log-reduction is greater as the sanitizing concentration, washing temperature and time increase (P < 0.001), and that reductions appear to be lower for leaf vegetables. Averaging over all types of fresh produce, the lowest log-reductions are attained by regular treatments with ozone gas (1.63 log CFU) and hydrogen peroxide (1.98 log CFU). Treatments with ozonized water, organic acids (citric acid, lactic acid, tartaric acid and malic acid) and chlorine reach comparable mean log-reductions in the range of 2.0 to 2.6 log CFU. A significantly higher bactericidal effect is obtained by calcium hypochlorite and peroxyacetic acid (3.2 log CFU), and chlorine dioxide gas and slightly acidic electrolyzed water (3.5 log CFU). Acidified sodium chlorite is by far the sanitizer that reaches the highest log-reduction (5.1 log CFU).
Significance: The resulting meta-analysis model has the capability to provide overall log-reduction estimates for E. coli O157:H7 when using a given sanitizer and sanitizing treatment.