A protocol for efficient recovery of pathogens or groups of microorganisms from fruits and vegetables must be established before proceeding with experiments designed to determine the efficacy of treatment with sanitizers or changes in populations as affected by storage conditions. Procedures for chemical decontamination should use standard weight-to-volume ratios (produce:treatment solution or atmosphere), whether applied as a dip, spray, or fog. A standard concentration of treatment solution applied for a standard time at a standard temperature, followed by neutralization of the active component using a standard volume and concentration of neutralizer should be defined. Whether the produce should be static, agitated, or hand rubbed during chemical treatment should be stated. Agitation, e.g., by placing the produce and treatment solution on a mechanical shaker or manually shaking, should be standardized. Conditions for separating the produce from the chemical treatment solution, washing with a specific neutralizer, and subsequent homogenization or washing in a specific volume of a given diluent should also be standardized. Controls that will reveal the effect of rinsing after treatment should also be included.
For physical decontamination treatments, standardization of conditions, e.g., temperature, irradiation, or pressure, would facilitate comparison of observations across laboratories. A neutralization step is not necessary in a standard protocol to measure the efficacy of physical treatments but, like protocols for determining the efficacy of chemical sanitizer treatments, standardization of diluent composition, ratio of produce weight:diluent volume, homogenization or washing procedure, preenrichment, enrichment, and direct plating media, and incubation conditions is necessary.
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