Research – Efficacy of a Mixed Peroxyorganic Acid Antimicrobial Wash Solution against Salmonella, Escherichia coli O157:H7 or Listeria monocytogenes on Cherry Tomatoes

Journal of Food Protection

A study was conducted to evaluate a new organic produce wash composed of a combination of organic acids and hydrogen peroxide, in the form of a mixed peroxyacid solution, against foodborne pathogens.  The mixed peroxyacid, composed of lactic acid, hydrogen peroxide and one or more fruit acids, was challenged against Salmonella enterica, E. coli O157:H7, or Listeria monocytogenes in suspension or on the surface of dip-inoculated cherry tomatoes.  Cherry tomatoes were also treated with 8 ppm of free chlorine added in the form of sodium hypochlorite (NaOCL).  When tested against planktonic cells in pure culture for 120 s, Salmonella, and E. coli O157:H7 were reduced by 7.5 and 7.1 log cycles with 0.40% of the peroxyacid solution, respectively, while L. monocytogenes decreased by 5.0 log by treatment with a 0.80% solution.  When cherry tomatoes were dip-inoculated and treated with 8 ppm free chlorine, Salmonella and E. coli O157:H7 populations decreased by 2.5 and 2.6 log, respectively, which were not significantly different than reductions incurred by sterile water rinses.  A 1.0% solution of peroxyacid solution, however, reduced the same microorganisms by 3.8 and 3.4 log per tomato, respectively, which was significantly greater ( P < 0.05) than reductions achieved by the 2 min sterile water rinse.  When dip-inoculated with L. monocytogenes, and treated, populations were reduced by 3.5 log per tomato with 1.0% peroxyacid solution which was greater ( P < 0.05) than reductions achieved by 8 ppm free Cl (2.6 log) or sterile water (1.7 log).  Results demonstrate that this peroxyacid combination antimicrobial wash may be an effective organic produce wash for preventing cross-contamination during the washing of cherry tomatoes, as well as being capable of inactivating up to 3.8, 3.4, and 3.5 log  per tomato of S. enterica, E. coli O157:H7 and L. monocytogenes , respectively.

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