Bromine-based Biocides for the Control of Salmonella on Fruits and Vegetables

Introduction: Salmonella is a pathogen of major concern in the fruits and vegetables industry.  Chlorine-based antimicrobial interventions are common in the fruits and vegetables industry but they have several limitations.  Bromine-based antimicrobials have been widely used in recreational and industrial water treatment for many years and have recently been approved for use in some food safety applications.  Some advantages of bromine-base biocides are: their effectiveness at a wider range of pH values than chlorine, low odor and minimal effect on organoleptic properties.

Purpose: To evaluate DBDMH (1,3-Dibromo-5,5-Dimethylhydantoin), a bromine-based biocide as means to control Salmonella on cantaloupes and tomatoes.

Methods: Salmonella enterica was grown overnight at 37°C in Luria-Bertani broth.  Cantaloupes and Roma tomatoes purchased from local stores were inoculated with 8 log CFU/cm² of Salmonella and allowed to attach at room temperature for 2 and 3 h, respectively.  Simulating a wash tank, cantaloupes or tomatoes were submerged in a biocide solution at room temperature for 5 or 3 min, respectively; the treatments included DBDMH at 300 or 400 ppm (as bromine), chlorine at 300 or 400 ppm (as bromine) and peroxyacetic acid (PAA) at 100 ppm.  After treatment, cantaloupes were drained and allowed to dry for 1 h, and 3.14 cm² of the surface were taken and homogenized.  Tomatoes were washed with distilled water for 1 min and rinsed for microbiological analysis.  The solutions were decimally diluted with 1% peptone water, and analyzed with APC 3M™ Petrifilm™ incubated at 37°C for 24 h.

Results: DBDMH on inoculated tomatoes showed bacterial reductions between 2.8 and 4.2 log CFU/cm².  DBDMH treatment at 300 ppm on inoculated cantaloupes showed a Salmonella reduction of 1.7 log CFU/cm² while PAA and chlorine had a reduction of 1.6 and 1.5 log CFU/cm², respectively.

Significance:   Bromine-based antimicrobials are an effective intervention to reduce pathogens in the fruits and vegetables industry.