Efficacy of FIT produce wash and chlorine dioxide on pathogen control in fresh potatoes

A commercial fresh pack potato operation was used as a model to evaluate FIT fruit and vegetable wash effectiveness in reducing levels of microorganisms on potatoes and in flume water. Fresh potatoes were washed in flume water with or without FIT, or treated with a spray bar utilizing either FIT, 9 ppm chlorine dioxide (CIO2), or a water control. Both flume treatments were also evaluated for APC and Gram-negatives. There were no significant differences in reduction of these microorganisms on treated or control potatoes. However, levels of Gram-negative bacteria in FIT-amended flume water were reduced by 5.95 log CFU/g, and the APC was reduced by 1.43 log CFU/g. To validate plant trial findings, this test was repeated using solutions of sterile potato flume water from the fresh pack operation, containing a typical level of dissolved and suspended solids. Treatment solutions prepared with flume water or deionized water containing FIT, 9 ppm CIO2, or a water control were inoculated with E. coli O157:H7, Salmonella Typhimurium, or Pectobacterium carotovorumssp. carotovorum. FIT and ClO2 prepared with deionized water reduced levels of microorganisms by >6.1 to 6.6 log CFU/g to below the detection limit. FIT prepared with flume water reduced levels of all organisms by >6.0 to 6.4 log CFU/g to below the detection limit, whereas ClO2 prepared from flume water reduced bacterial levels of all organisms by only 0.7 to 1.4 log CFU/g. Neither FIT nor ClO2 was particularly efficacious against E. coli O157:H7, S. Typhimurium, APC, yeasts, or molds on potato surfaces.