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Microbial safety and overall quality of cantaloupe fresh-cut pieces prepared from whole fruit after wet steam treatment

Ukuku, Dike O., Geveke, David J., Chau, Lee, Niemira, Brendan A.
International journal of food microbiology 2016 v.231 pp. 86-92
Escherichia coli O157, Listeria monocytogenes, Salmonella, aerobiosis, bacteria, cantaloupes, color, cutting, foodborne illness, fresh-cut produce, inoculum, pathogens, salmonellosis, shelf life, spoilage, steam
Fresh-cut cantaloupes have been associated with outbreaks of Salmonellosis. Minimally processed fresh-cut fruits have a limited shelf life because of deterioration caused by spoilage microflora and physiological processes. The objectives of this study were to use a wet steam process to 1) reduce indigenous spoilage microflora and inoculated populations of Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes on the surface of cantaloupes, and 2) reduce the populations counts in cantaloupe fresh-cut pieces after rind removal and cutting. The average inocula of Salmonella, E. coli O157:H7 and Listeria monocytogenes was 107CFU/ml and the populations recovered on the cantaloupe rind surfaces after inoculation averaged 4.5, 4.8 and 4.1logCFU/cm2, respectively. Whole cantaloupes were treated with a wet steam processing unit for 180s, and the treated melons were stored at 5°C for 29days. Bacterial populations in fresh-cut pieces prepared from treated and control samples stored at 5 and 10°C for up to 12days were determined and changes in color (CIE L*, a*, and b*) due to treatments were measured during storage. Presence and growth of aerobic mesophilic bacteria and Salmonella, E. coli O157:H7 and L. monocytogenes were determined in fresh-cut cantaloupe samples. There were no visual signs of physical damage on all treated cantaloupe surfaces immediately after treatments and during storage. All fresh-cut pieces from treated cantaloupes rind surfaces were negative for bacterial pathogens even after an enrichment process. Steam treatment significantly (p<0.05) changed the color of the fresh-cut pieces. Minimal wet steam treatment of cantaloupes rind surfaces designated for fresh-cut preparation will enhance the microbial safety of fresh-cut pieces, by reducing total bacterial populations. This process holds the potential to significantly reduce the incidence of foodborne illness associated with fresh-cut fruits.