Purpose: A new decontamination method using sodium chlorite and hydrochloric acid, in a sequential application to form chlorine dioxide in situ on the surfaces of produce, has been shown to significantly reduce pathogens inoculated on cantaloupe rinds. This study further examined the efficacy of the chlorite concentrations for decontaminating whole cantaloupes.
Methods: Three 1x1 cm rind surfaces of whole cantaloupes were spot-inoculated with a 5-strain cocktail of Salmonella spp. or Listeria monocytogenes. Each inoculated cantaloupe was submerged in 3 L sodium chlorite solution (0.4, 0.8, 1.2, and 1.6%) for 5 min, dried for 30 min, submerged in 3 L 6 mM HCl for 5 min, and dried for 30 min. After treatments, the inoculated rind sections were removed for enumeration of Salmonella spp. and L. monocytogenes using XLT-4 and PALCAM agars, respectively.
Results: The initial populations of Salmonella spp. and L. monocytogenes on the rinds were approximately 5.8 log CFU/g. Treatments with 1.2 and 1.6% chlorite reduced 5.4-5.8 log of Salmonella spp. and 5.2-5.4 log of L. monocytogenes; whereas 0.4 and 0.8% chlorite reduced 3.2-4.4 log of the populations. Higher concentrations of chlorite caused higher reductions of both pathogens. Salmonella spp. were more susceptible to the treatments than L. monocytogenes. Results showed that sequential treatments using >1.2% chlorite and 6 mM HCl could achieve a >5 log reduction of Salmonella spp. and L. monocytogenes on whole cantaloupe surfaces.
Significance: The new sequential treatment may be used for surface decontamination of whole cantaloupes to improve the product’s microbiological quality and safety.