Effect of time and storage temperature on injured salmonella bacteria on honeydew and cantaloupe melons after sanitizing treatments and fresh-cut preparation

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

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cantaloupes and honeydew melons inoculated with Salmonella bacteria were washed at 20C with water (room temperature), 1.5% hydrogen peroxide (room temperature), 1.5% hydrogen peroxide and water at 70C, respectively. Some of the fresh-cut pieces prepared from these melons were left at room temperature for 30 min, and 1 h before refrigeration while some were put in the refrigerator immediately after preparation. A higher population of Salmonella was recovered from untreated cantaloupes compared to honeydew melons. Populations of Salmonella bacteria in fresh-cut pieces treated with 1.5% hydrogen peroxide and water at 70C was below detection even when fresh-cut pieces were left at room temperature for 1 h before refrigeration. There were no sign of deterioration on treated melons suggesting that melons treated.

Technical Abstract: Consumers’ demand for food products that are safe, fresher and convenient for use has led to consumption of contaminated melons resulting to foodborne outbreaks. Cantaloupes and honey dew melons were inoculated with Salmonella bacteria at 4.5 and 3.9 log CFU/cm2, respectively. The melons were washed at 20C with water (H2O, room temperature), 1.5% hydrogen peroxide (H2O2) at 20C, 1.5% H2O2 at 70C, and H2O at 70C for 3 min. Fresh-cut pieces from treated and untreated melons were prepared and left at room temperature for 0, 30 min, and 1 h before storage at 5C. Behavior of injured microbial populations on treated melons stored at 5, 10 and 20C were investigated at 0, 2 and 4 day of storage. Aerobic mesophilic bacteria, yeast and mold, and the inoculated populations of Salmonella determined immediately before treatments were higher for whole cantaloupe (4.5 log CFU/cm2) and fresh-cut (2.3 log CFU/g) pieces than for whole honeydew (3.9 log CFU/cm2) and its fresh-cut (1.9 log CFU/g) pieces. A higher population of injured Salmonella bacteria was recovered from whole cantaloupe than honeydew melons treated with 1.5% H2O2 at 20C.And these populations on melons treated with 1.5% H2O2 at 70C were significantly (p<0.05) reduced. Immediate storage of treated melons at 5C further inactivated the injured populations compared to melons left at room temperature suggesting further inactivation of the injured bacterial cells by the cold storage temperature. Visual observation of minimal thermal treated whole melons showed no sign of deterioration throughout storage at 5C for 14 days. Therefore, melons treated with 1.5% H2O2 or H2O at 70C, with immediate storage at 5C before fresh-cut preparation, would not pose a microbial safety issue for fresh-cut pieces.