Research Impacts: The watermelon industry funded a microbial study through the University of California Davis with the specific objective to determine the survival and growth potential of inoculated E. coli O157:H7, Salmonella, and Shigella on the outer rind of watermelon under typical retail distribution conditions. Pathogens selected for the studies were those that had been used by Drs. Suslow and Harris for inoculating other fruits and vegetables, and the selected strains represented a broad range of isolates that have been found in association with produce.
The results demonstrate that Salmonella, E. coli O157:H7, and Shigella sonnei behave on watermelon rind in a manner similar to that of other smooth surface produce. The smooth rind of the watermelon did not provide an irregular surface where the bacteria could get caught and remain.
Because of the smooth rind washing the watermelon under running tap water sufficed to remove any pathogens from the fruit. (Source: Evaluating the Potential for Human Pathogens to Grow or Survive on the Surface of Watermelon Rind Under Typical Retail Distribution Conditions. Principle Investigators: Linda J. Harris, Ph.D. , Extension Food Safety, Dept. of Food Science and Technology Specialist, University of California, Davis; Trevor V. Suslow, Ph.D. ,Extension Postharvest Specialist, Dept. of Vegetable Crops, University of California, Davis)
A study by the internationally known and acclaimed food safety expert, Dr. Larry R. Beuchat, states ?Growth [Escherichia coli 0157:H7] was more prolific on cantaloupe than on watermelon rind?. (Source: Survival and Growth of Enterohemorrhagic Escherichia coli 0157:H7 in Cantaloupe and Watermelon, BRENDA A. DEL ROSARIO and LARRY R. BEUCHAT* Center for Food Safely and Quality Enhancement and Department of Food Science and Technology, University of Georgia) (Journal of Food Protection 58:105-107. 1995)
Additionally, USDA determined that watermelon is one of the "cleanest" fruit and vegetables. Martha Lamont, Director, USDA, AMS, S&T Monitoring Programs Office said, "Of the fruit and vegetables tested in 2005, watermelon and eggplant had the lowest number of samples with detectable residues and therefore, were the cleanest in the group". USDA replaced watermelon with another crop in the next phase of study.