Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 9/30/2002
Publication Date: 12/1/2002
Citation: Ukuku, D.O. 2002. Behavior of listeria monocytogenes inoculated on whole cantaloupe and fresh-cut pieces. In: Proceedings of the United States-Japan Cooperative program in Natural Resources (UJNR) Protein Resources Panel, 31st Annual meeting, December1-6, 2002 Monterey, California. P. K-1-K-9.
Technical Abstract: Attachment and survival of Listeria monocytogenes on external surfaces (rind) of inoculated cantaloupe, transfer of the pathogen from unsanitized and sanitized rinds to fresh-cut tissues during cutting and growth on fresh-cut pieces were investigated. Surface treatment with 70% ethanol to reduce the native microflora on treated melon, followed by immersion in a four strain cocktail of L. monocytogenes (108 CFU/ml) for 10 min, deposited 4.2 log10 CFU/cm2 and 3.5 log10 CFU/cm2 on treated and untreated cantaloupe rinds, respectively. L. monocytogenes survived on the treated or untreated cantaloupe rinds for up to 15 days during storage at 4oC and 20oC, but populations declined by approximately 1 to 2 log10 CFU/cm2. Fresh-cut pieces prepared from inoculated whole cantaloupes stored at 4oC for 24 h post inoculation were positive for L. monocytogenes. Washing inoculated whole cantaloupes in solutions containing 1000 ppm chlorine or 5% hydrogen peroxide for 2 min at 1 to 15 days storage at 4oC post inoculation resulted in a 2.0 to 3.5 log reduction in L. monocytogenes on the melon surface. Fresh-cut pieces prepared from the sanitized melons were negative for L. monocytogenes. After direct inoculation onto fresh-cut pieces prepared from sanitized cantaloupe, L. monocytogenes grew, but survived up to day 6 on fresh-cut pieces prepared from unsanitized cantaloupe during 15 days of storage at 4oC. Growth was enhanced in fresh-cut pieces with low population of native microflora during storage at 4oC. At 8 and 20oC of storage growth of L. monocytogenes on fresh-cut pieces was suppressed while populations of native microflora increased. It is concluded that sanitizing with chlorine or hydrogen peroxide has the potential to reduce or eliminate the transfer of L. monocytogenes on melon surfaces to fresh-cut pieces during cutting. Also the data suggests that the native microflora of cantaloupe inhibits growth of the pathogen in fresh-cut pieces.