Factors Affecting the Efficacy of Commercial Post-harvest Washing of Fresh-cut Leafy Greens and the Dynamics of Microbial Populations within a Commercial Wash Process

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Zahedi, Hamed
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University of Guelph

Produce washing remains a key intervention despite only achieving a 1-2 log reduction and potential for cross-contamination. Our objectives were to establish the wash water parameters that impact on the efficacy of washing leafy greens within commercial settings. Sampling visits were performed at two commercial fresh-cut processors with the microbial loading of raw material, pre-wash and post-wash product being determined. At the same time water quality parameters (bacterial loading, turbidity, conductivity, and temperature) were measured. Microbial community populations were evaluated using Eco-plates TM and 16S rDNA. From the multiple parameters tested, the LCR could be correlated to turbidity and ORP. Interestingly, the LCR was independent of microbial loading of the water yet increased levels correlated with cross-contamination events as observed using microbial population profiling. Washing of leafy greens is limited and alternative treatments should focus on how to minimize cross-contamination as opposed to focusing on log count reductions.

Washing efficacy, Monitoring quality of wash water, Microbial community, APC, Coliform, Lettuce, Spinach, Leafy green, Frsh-cut produce, Cross-contaminatin, Pre-washing, Biocidal tank, AC impedance, Turbidity, ORP, pH, 16 S rDNA, 16 S rRNA, Ecoplate, Metabolic fingerprint, Bacterial DNA fingerprint, Food Safety, CCP, Sanitizer, Chlorine, PAA, Peracetic Acid, LCR, Microbial deposition