Leverentz, B., Produce Quality and Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Conway, W.S., Produce Quality and Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, MD 20705, United States, Department of Epidemiology and Preventive Medicine, University of Maryland, Baltimore, MD 21201, United States
Alavidze, Z., Eliava Institute of Bacteriophage, Microbiology and Virology, Georgian Academy of Sciences, Tblisi, Georgia, Department of Epidemiology and Preventive Medicine, University of Maryland, Baltimore, MD 21201, United States
Janisiewicz, W.J., Appalachian Fruit Research Station, Agricultural Research Service, U.S. Department of Agriculture, 45 Wiltshire Road, Kearneysville, WV 25430, United States
Fuchs, Y., Department of Postharvest Science of Fresh Produce, ARO, Volcani Center, Bet Dagan 50250, Israel
Camp, M.J., Biometrical Consulting Service, Henry A. Wallace Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Chighladze, E., Department of Epidemiology and Preventive Medicine, University of Maryland, Baltimore, MD 21201, United States
Sulakvelidze, A., Department of Epidemiology and Preventive Medicine, University of Maryland, Baltimore, MD 21201, United States

The preparation and distribution of fresh-cut produce is a rapidly developing industry that provides the consumer with convenient and nutritious food. However, fresh-cut fruits and vegetables may represent an increased food safety concern because of the absence or damage of peel and rind, which normally help reduce colonization of uncut produce with pathogenic bacteria. In this study, we found that Salmonella Enteritidis populations can (i) survive on fresh-cut melons and apples stored al 5°C, (ii) increase up to 2 log units on fresh-cut fruits stored at 10°C, and (iii) increase up to 5 log units at 20°C during a storage period of 168 h. In addition, we examined the effect of lytic, Salmonella-specific phages on reducing Salmonella numbers in experimentally contaminated fresh-cut melons and apples stored at various temperatures. We found that the phage mixture reduced Salmonella populations by approximately 3.5 logs on honeydew melon slices stored at 5 and 10°C and by approximately 2.5 logs on slices stored at 20°C, which is greater than the maximal amount achieved using chemical sanitizers. However, the phages did not significantly reduce Salmonella populations on the apple slices at any of the three temperatures. The titer of the phage preparation remained relatively stable on melon slices, whereas on apple slices the titer decreased to nondetectable levels in 48 h at all temperatures tested. Inactivation of phages, possibly by the acidic pH of apple slices (pH 4.2 versus pH 5.8 for melon slices), may have contributed to their inability to reduce Salmonella contamination in the apple slices. Higher phage concentrations and/or the use of low-pH-tolerant phage mutants may be required to increase the efficacy of the phage treatment in reducing Salmonella contamination of fresh-cut produce with a low pH.