Delmopinol Hydrochloride Spray Reduces Salmonella on Cantaloupe Surfaces

Introduction: Melons can be contaminated at centralized packaging facilities during post-harvest operations and are vulnerable to microbial cross contamination due to contaminated water tanks, grading/sorting equipment, transport vehicles, and workers. Appropriate post-harvest washing and sanitizing procedures can help control Salmonellaand other pathogens on cantaloupe or other melons.  Since the surfaces of cantaloupes are highly rough or irregular, bacteria can easily attach to these surfaces and become difficult to remove. 

Purpose: Delmopinol Hydrochloride (Delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis.  The application of Delmopinol to cantaloupe may be an alternative post-harvest technique to reduce the frequency and level of Salmonellacontamination.

Methods: Cantaloupe (Athena and Hale's Best Jumbo cultivars) ring plugs (2.5 cm. dia.) were inoculated with a broth culture of Salmonella Michigan (approx. 1.0 x 10⁹CFU/ml).  After 15 min, plugs were sprayed with 10 ml of a Delmopinol solution (0% or 1.0%) and held at 37°C for 1 h and 24 h.  Melon plugs were diluted with Butterfield's Phosphate Buffer, shaken and sonicated, and solutions were enumerated on tryptic soy agar.  The texture quality and color of additional melon samples were evaluated after Delmopinol spray treatments over 14 days storage at 4°C.

Results: A 1.0% (vol/vol) application of Delmopinol reduced Salmonella levels 1.6 - 4.4 log CFU/ml in comparison to the field control (P < 0.01). No significant differences (P > 0.05) were observed in the texture and color of Delmopinol treated melons. Storage of melons treated with 1.0% Delmopinol solution for 1 h had a greater effect on reducing attachment of Salmonella compared to 24 h treatment.

Significance: A surface spray application of Delmopinol Hydrochloride can be an alternative antimicrobial post-harvest treatment that will interfere with the mechanism of biofilm adherence, which can make surface bacteria more susceptible to sanitizers or physical removal.