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United States Department of Agriculture

Agricultural Research Service

Title: Bacteriophage As a Biocontrol Method for Salmonella and Listeria on Fresh Cut Fruit

Authors
item Leverentz, Britta
item Conway, William
item Alavidze, Zemphira - UNIV. OF MARYLAND
item Janisiewicz, Wojciech
item Camp, Mary
item Sulaevelidze, Alexander - UNIV. OF MARYLAND

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: April 25, 2001
Publication Date: N/A

Technical Abstract: Fresh-cut fruits and vegetables may represent an increased food safety concern because of the absence or damage of peel and rind that normally help reduce colonization of uncut produce with pathogenic bacteria. In this study, Salmonella Enteritidis populations survived on fresh-cut melons and apples stored at 5 degrees C and increased up to 2 to 5 log units on fresh-cut fruits stored at 10 degrees C and 20 degrees C over a storage period of 168 h. Listeria monocytogenes populations increased at 10 degrees C on honeydew melons over the same time period. In addition, we examined the effect of lytic, Salmonella-specific and Listeria-specific phages on reducing bacterial numbers in experimentally contaminated fresh-cut melons and apples stored at various temperatures. The phage mixture reduced Salmonella populations by up to 3.5 logs on honeydew melon slices, which is greater than the maximal amount achieved using chemical sanitizers. However, the phages did not reduce Salmonella populations on the apple slices at any of the three temperatures. Listeria populations were reduced by the phage mixture by up to 1.9 log units on honeydew. The titer of the phage preparation remained relatively stable on melon slices, whereas, on apple slices, the titer decreased to non-detectable levels in 48 h at all temperatures tested. Inactivation of phages, possibly by the acidic pH of apple slices (pH 4.2 vs. pH 5.8 for melon slices), may contribute to their inability to reduce Salmonella contamination in apple slices. Higher phage concentrations and/or the use of low-pH-tolerant phage mutants may be required in order to increase the efficacy of the phage treatment in reducing Salmonella contamination of fresh-cut produce with a low pH.

Last Modified: 8/29/2014