T7-07 Effect of Thermal and Non-thermal Treatments on Bacterial Populations on Melon Rind Surfaces

Monday, July 27, 2015: 10:30 AM
C124 (Oregon Convention Center)
Dike Ukuku, U.S. Department of Agriculture-ARS-ERRC, Wyndmoor, PA
Sudarsan Mukhopadhyay, Microbial Food Safety Grp., ARS, USDA, Wyndmoor, PA
Modesto Olanya, USDA-ARS-ERRC, Wyndmoor, PA
Introduction: Consumers demand for fresh produce has led to higher incidence of foodborne illness arising from consumption of cantaloupes contaminated with bacterial pathogens. To solve this food safety problem, the produce industry and research institutions are working to develop a better sanitizer treatment that can eliminate or minimize bacterial transfer to fresh-cut pieces during preparation.

Purpose: In this study, we evaluated the effect of sanitizer treatments on microbial reduction on cantaloupe rind surface. Also, changes on cantaloupe rind surface as a result of treatments on the melons were evaluated. 

Methods: Whole cantaloupes were purchased from a wholesale distributor and were inoculated with Salmonella spp. at 4.52 log CFU/cm2. The melons were treated as follows; water washed, 1,000 ppm chlorine, 3.5% hydrogen peroxide, and heated 3.5% hydrogen peroxide at 80°C. All treatments were for 5 min and the rind surfaces were examined with scanning electron microscopy and bacterial inactivation due to treatments was determined using plate count and XLT4 agar plates. 

Results: Total mesophilic bacteria on cantaloupe rind surface before inoculation averaged 4.8 log CFU/cm2. After treatments with chlorine and unheated hydrogen peroxide, mesophilic aerobes were reduced to 2.2 and 1.9 log CFU/cm2 while Salmonella was reduced to 1.9 and 1.6 log CFU/cm2, respectively. The surviving population for Salmonella spp. on cantaloupe rind after treatment with heated 3.5% hydrogen peroxide was below detection. Changes on cantaloupe rind surfaces were observed and were dependent on the type of treatment. Internal flesh of all treated cantaloupes was not affected, probably due to the thickness of the melon rind. Microbial populations on fresh-cut cantaloupe pieces prepared from heat treated melons were significantly lower than untreated, chlorine, and 3.5% hydrogen peroxide treated melons 

Significance: Treating whole melon surfaces with heated 3.5% hydrogen peroxide before fresh-cut preparation will improve the microbial safety and quality of the prepared fresh-cut pieces.