This study carried out a systematic quantitative analysis of published literature on the efficacy of essential oils (EOs) as sanitizers in fresh leafy vegetables (FLVs). Efficacy of EO was measured by determining if their application could cause a reduction of microbial population in FLV, as well as by identifying experimental factors that might affect the achieved reduction levels. Data on efficacy of EO to reduce the microbial population and experimental conditions were collected from selected studies and compiled for a distribution and relational analysis. Reduction of an artificial inoculum and/or natural microbiota of FLV caused by 14 different EO were measured in 404 (73.8%) and 143 (26.2%) experiments, respectively. Results of quantitative analysis showed that EO are consistently effective to reduce microbial population in FLV either when the target microorganisms are forming an artificial inoculum or the natural microbiota, being overall similarly effective to or more effective than substances used ordinarily as sanitizers. EO were more effective to reduce the population of microorganisms forming an artificial inoculum than the natural microbiota. EO concentration and inoculum size had no significant effect on achieved reductions. Duration of sanitization treatment with EO had significant effect on achieved reductions and highest reductions were found when the sanitization time was >3 min. Although with the inherent variability in experimental designs found in available literature, the results of this quantitative analysis provide strong evidence that EO are promising candidates for use in strategies to sanitize FLV.
Keywords: Antimicrobial efficacy; essential oil; meta-analysis; sanitization; vegetables.