Antimicrobial treatments and cold storage inactivates injured salmonella bacteria on melon surfaces and fresh-cut pieces

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

Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2019
Publication Date: 4/10/2019
Citation: Ukuku, D.O., Mukhopadhyay, S., Olanya, O.M., Niemira, B.A. 2019. Antimicrobial treatments and cold storage inactivates injured salmonella bacteria on melon surfaces and fresh-cut pieces. Journal of Food Processing and Preservation. https://doi.org/10.1111/jfpp.13943.
DOI: https://doi.org/10.1111/jfpp.13943

Interpretive Summary: Whole honeydew and cantaloupe melons were inoculated with Salmonella and then treated with 1.5% hydrogen peroxide at room temperature and at 70C for 3 min. Microbial safety was studied and the effects of treatments and cold storage on microbial reduction and overall appearance of treated melons were investigated. Minimal thermal treatments with 1.5% hydrogen peroxide at 70C reduced total microbial transfer to the interior during fresh-cut preparation, and enhanced the microbial safety of the fresh-cut pieces. Also, the minimal thermal treatments with 1.5% hydrogen peroxide at 70C improved appearance of the treated melons suggesting that the process would be a better alternative than conventional wash process.

Technical Abstract: Fresh-produce industries are looking for processing treatments that would provide safe fresh-cut fruits and vegetables without compromising quality. In this study, cantaloupes and honeydew melons inoculated with 107 CFU/ml Salmonella bacteria were treated with 1.5% hydrogen peroxide (H2O2) at 20oC and minimally treated at 70oC for 3 min before storage at 5, 10 and 20oC. Fresh-cut pieces prepared at each day of storage were immediately placed inside the refrigerator (5oC) while some pieces were left at room temperature (20oC) for 0, 30, and 60 min before refrigeration. Salmonella bacteria recovered from the cantaloupe and honeydew melon rind surfaces after inoculation averaged 4.5 and 3.9 log CFU/cm2, respectively before antimicrobial treatments. A higher populations of injured Salmonella bacteria was recovered on whole cantaloupes than honeydew melons treated with 1.5% H2O2 at 20oC. Cold storage of treated melons at 5oC led to significant (p<0.05) reduction of the injured bacteria and below detection in fresh-cut pieces even after enrichment process. Based on the results, minimal thermal antimicrobial processing of honeydew and cantaloupe melons at 70oC for 3 min will kill Salmonella bacteria and reduce transfer to fresh-cut pieces during fresh-cut preparation.