In the summers of 2011 and 2012, the United States was hit by two deadly food poisoning outbreaks caused by cantaloupe. Bacteria on that product are especially insidious, since they can cling to the webbing on the surface of the fruit. Washing does not remove all of the bacteria. So a study published in the Journal of Food Protection has found that it is crucial that cantaloupe always been refrigerated.
The researchers looked at the behavior of Listeria monocytogenes, the bacteria responsible for the 2011 Jensen Farms cantaloupe outbreak that sickened 147 people in 28 states. At least 33 people died in this outbreak, which was caused by five subtypes of the bacteria.
In the study, whole cantaloupes were inoculated with L. monocytogenes for 10 minutes, then air dried and treated three different ways: unwashed, water washed, and washed with a 2.5% hydrogen peroxide solution. Fresh cut pieces from these melons were refrigerated and left at room temperature for 48 hours.
They found that only the hydrogen peroxide solution reduced the populations of bacteria. And the bacteria was transferred from melon rinds to fresh cut pieces. Finally, increased storage temperatures enhanced the bacterial growth. Researchers said that, “the results of this study confirmed the need to store fresh-cut cantaloupes at 5 degrees C (41 degrees F) immediately after preparation to enhance the microbial safety of the fruit.”
Another study found that immersing cantaloupes in 168 degrees F water for 3 minutes reduced the bacterial count to “almost non detectable levels” according to the scientists. The USDA is researching this treatment to see if it can be used commercially.
Why can’t we ask how the listeria is getting on fruit in the first place? Shouldn’t we be trying to stop the cause vs treating it? We shouldn’t have to go to these measures.
Good question. Unfortunately, pathogenic bacteria is everywhere. It gets on cantaloupe via runoff from farm fields, from wild animals, in dirty packing sheds, and in packing and shipping containers.