Purpose: This study was performed to produce science based data, which are needed to generate practical and effective decontamination strategies for irrigation water to mitigate contamination of produce by foodborne pathogens at the production level.
Methods: Well and pond irrigation water were sampled from four vegetable farms on the Eastern Shore of Virginia and inoculated with S. enterica, E. coli O157:H7, or L. monocytogenes. The efficacy of four commercial sanitizers (XY12, CDG Solution 3000™, Sanidate 5.0, and Sanidate 12.0) with different active ingredients was evaluated.
Results: The populations of the three foodborne pathogens were efficiently reduced (>5 log) after 30 min treatment with each tested sanitizers. Listeria monocytogenes and E. coli O157:H7 were more tolerant to one minute treatments with tested sanitizers compared to S. enterica. The pathogen populations were significantly higher in pond water compared to well water, under certain treatments. The depletion of free chlorine and chlorine dioxide with XY12 and CDG3000 (82-96%) were significantly higher than with peracetic acid (3-61%) in Sanidate products. The depletions were not significantly different between pond and well water. Water turbidity was significantly lower in well water compared with pond water (P<0.05). Coliforms and E. coli in tested water samples were completely eliminated after 30 min sanitizer treatments. The pH of treated irrigation water was remained in the proper range for plant growth (6-7.5).
Significance: These results provide clues for generating mitigation strategies for foodborne pathogens in irrigation water used for produce production.