Deza MAAraujo MGarrido MJ.

Institute of Food Research and Analysis, University of Santiago de Compostela, Santiago de Compostela, Spain.

AIMS: To determine the efficacy of neutral electrolyzed water (NEW©) in killing Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes, as well as nonpathogenic E. coli, on the surface of tomatoes, and to evaluate the effect of rinsing with NEW© on the organoleptic characteristics of the tomatoes. METHODS AND RESULTS: The bactericidal activity of NEW©, containing 444 or 89 mg l(-1) of active chlorine, was evaluated over pure cultures (8.5 log CFU ml(-1)) of the above-mentioned strains. All of them were reduced by more than 6 log CFU ml(-1) within 5 min of exposure to NEW©. Fresh tomatoes were surface-inoculated with the same strains, and rinsed in NEW© (89 mg l(-1) of active chlorine) or in deionized sterile water (control), for 30 or 60 s. In the NEW© treatments, independent of the strain and of the treatment time, an initial surface population of about 5 log CFU was reduced to <1 log CFU, and no cells were detected in the washing solution by plating procedure. A sensory evaluation was conducted to ascertain possible alterations in organoleptic qualities, yielding no significant differences with regard to untreated tomatoes. SIGNIFICANCE AND IMPACT OF THE STUDY: Rinsing in NEW© reveals as an effective method to control the presence of E. coli O157:H7, S. enteritidis and L. monocytogenes on the surface of fresh tomatoes, without affecting their organoleptic characteristics. This indicates its potential application for the decontamination of fresh produce surfaces.