The USDA’s Agricultural Research Service in Pennsylvania found in 2006 that hot water immersion treatment for cantaloupes can help make that product safer. The treatment has been effective in the lab and might be used in processing plants.
The Jensen Farms cantaloupe Listeria outbreak in the summer of 2011 has prompted the industry and scientists to take a look at new ways to make produce safer. That incident caused 30 deaths and one miscarriage. Produce was the source for 1/3 of the food poisoning outbreaks in 2011.
For the treatment, the fruit is placed in 168 degrees F water for 3 minutes. This kills Salmonella bacteria that scientists put on the cantaloupe peel. The cantaloupe flesh is not affected, since the thick peel insulates it against the hot water.
Bassam Annous, research microbiologist at the Service, said, “We saw really good kills, to almost non detectable levels of the pathogen after treatment.” This treatment may also extend the shelf life of the product, especially after the cantaloupe is cut, since it kills bacteria that cause the fruit to spoil. The heat treatment also reduces the “respiration rate” of the cut fruit, retarding spoilage.
The USDA is currently researching how the treatment could “be commercial-scale friendly so the industry would be willing to use based on the criteria of what they do,” Annous said.
Other methods for treating cantaloupe and other produce include chemical baths of a chlorine solution (which is different from adding chlorine to rinse water) and spraying with lactic acid. At Jensen Farms, the company stopped adding chlorine to the water used to wash cantaloupes coming in from the field, with the support of third-party auditors Primus Labs. The outbreak occurred one month after this change.
