Growth of Salmonella spp. in Cantaloupe, Watermelon, and Honeydew Melons

The ability of Salmonella spp. to grow on the interior tissues of cantaloupe, watermelon, and honeydew melons was investigated. Pieces of rind-free melons (pH 5.90-6.67) and tryptic soy broth (TSB, pH 5.90) were inoculated with a mixed culture (approximately 100 CFU/g or ml) containing equal proportions of five species of Salmonella ( S. anatum , S. Chester , S. havana , S. poona , and S. senftenberg ). Inoculated melon pieces and TSB were incubated for 24 h at 5 or 23°C. Viable populations of salmonellae were determined by surface plating test portions on Hektoen enteric agar. Results indicated that Salmonella growth was rapid and prolific on the melons and in TSB at 23°C incubation. Final populations on watermelons were approximately 1.0 log₁₀ greater than populations on cantaloupe and honeydew and in TSB. Although viable Salmonella populations on melons and in TSB did not increase during the 24-h incubation at 5°C, little or no decrease in viable populations was observed.