Purpose: A non-oxidizing disinfectant consisting of a synergistic combination of plant extracts and low concentrations of silver and copper ions (MicroPure Technologies LLC, (MPT)) was evaluated for its ability to reduce microbial load. The efficacy of the disinfectant as a produce wash was compared to free chlorine at 50 mg/l (pH 6.0) in over 60 experiments.
Methods: Mixtures of Salmonella enterica, Listeria monocytogenes and Escherichia coli O157:H7 (three strains per species) were used as inocula. Bacteriophage MS2 was tested, alone and in combination with the bacteria. The disinfectants were added to solutions of 5% sterile vegetable juice prior to inoculating with the bacteria or viruses. The suspensions were mixed thoroughly and constant agitation applied. Samples were removed after 1, 2 and 3 minutes of contact time. A solution of 5% juice with inoculum was used as a control.
Results: The chlorine rinse achieved typical reductions of <1 – 2 logs for bacteria and MS2. Conversely the non-oxidizing MPT disinfectant consistently achieved reductions of 4 - 6+ logs for all three bacteria and MS2 at both 4°C and 20°C. Repeated bacterial challenges of wash water containing a single dose of MPT disinfectant demonstrated that its disinfectant efficacy was largely unaffected, thus indicating the ability to reuse the disinfectant multiple times.
Significance: These results suggest that MPT was superior to chlorine in reducing the microbial burden in water, which suggests MPT will reduce the risk of cross contamination of produce during washing operations prior to packaging / distribution.