Injury and recovery of salmonella, Escherichia coli 0157:H7 and Listeria Monocytogenes on cantaloupe rind surfaces after hyrdogren peroxide and minimal thermal treatment

Authors: Ukuku, Dike; Mukhopadhyay, Sudarsan; Olanya, Modesto; Niemira, Brendan

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2017
Publication Date: 7/9/2017
Citation: Ukuku, D.O., Mukhopadhyay, S., Olanya, O.M., Niemira, B.A. 2017. Injury and recovery of salmonella, Escherichia coli 0157:H7 and Listeria Monocytogenes on cantaloupe rind surfaces after hyrdogren peroxide and minimal thermal treatment.[Abstract]. International Association for Food Protection., Tampa, Florida., Volume 1, Page 1.

Interpretive Summary:

Technical Abstract: Introduction: Produce surface structures vary and complicate decontamination treatments for reducing attached bacteria. Purpose: The objective of this study on survival and recovery of injured population of Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes on cantaloupe rind surfaces after treatments with water at 22C, water at 70C, 3% hydrogen peroxide (H2O2) at 22C, and a combination of 3% H2O2 and water at 70C for 300 s with storage at 5 and 22C for 7 days. Methods: Whole cantaloupes purchased from super market were stored at room temperature (22C ) for 18 h to come to room temperature. Melons were inoculated with Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes inoculums at 104 CFU/cm2, respectively and then were treated for 300 s with 1) water at 22C, 2) water at 70C, 3) 3% hydrogen peroxide (H2O2) at 22C, 4) a combination of 3% H2O2 and water at 70 degrees C. Surviving populations including injured bacteria were enumerated on different selective agar plates and the populations inactivated were calculated. Results: Washing with water alone did not cause any injury or inactivation of each bacterium. Among the surviving populations of Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes recovered after treatments with 3% H2O2 alone, 20%, 15% and 2%, of the surviving populations, respectively were injured bacteria. Populations of injured pathogens on treated cantaloupe lasted for 24 h on cantaloupe rind surfaces stored at 22C but declined to < 2 CFU/cm2 on melons stored at 5C. Percent surviving injured populations for all bacterium on 70C water treated melons averaged < 2% for all pathogens tested. Hot water and a combination treatment with 3% H2O2 at 70C led to 4 log inactivation of all bacterial pathogens. Populations transferred to fresh-cut pieces were below detection even after enrichment of the fresh-cut samples. Significance: The results of this study indicate that surviving injured populations of Salmonella, E. coli O157:H7 and L. monocytogenes on whole cantaloupes processed for 300s at 70C would not pose a microbial safety issue for fresh-cut pieces prepared from treated cantaloupes, either when consumed immediately or stored at 5 degrees C for later consumption.