Biocontrol of Listeria on cantaloupes with lactic acid bacteria

Abstract

Efficacy of lactic acid bacteria (LAB) Lactobacillus plantarum and Pediococcus pentosaceus for reducing Listeria on cantaloupes was investigated. Cantaloupe surfaces inoculated with Listeria innocua and Listeria monocytogenes in preharvest and postharvest studies, respectively, were treated with or without LAB. Listeria populations were enumerated on days 0, 1, 5, and 7. At the preharvest level, treatment with unwashed LAB (cultures grown in De Man, Rogosa, and Sharpe) significantly reduced L. innocua by 2.1 log and 1.5 log CFU/cm2 on cantaloupes harvested on days 5 and 7, respectively. At the postharvest level, both unwashed LAB and washed LAB (cultures resuspended in phosphate buffer saline) significantly reduced L. monocytogenes by >2.0 log CFU/cm2 on cantaloupes after 7 days of storage at 25°C; the unwashed LAB treatment exerted higher anti-Listeria efficacy than the washed LAB. Results suggest that these LAB strains offer potential application for reducing Listeria contamination on cantaloupes at preharvest and postharvest levels. Practical applications Listeriosis associated with the consumption of cantaloupes have resulted in 153 illnesses, 148 hospitalizations, and 33 deaths in the United States between 2009 and 2013, which highlight the need for effective interventions to improve cantaloupe safety. Cantaloupes may be contaminated with Listeria at the farm level or during wash step at the packing facility. Lactic acid bacteria (LAB) including Lactobacillus plantarum and Pediococcus pentosaceus can be potentially utilized as biocontrol agents on the surface of the cantaloupes at the farm level or during postharvest wash to reduce the populations of Listeria on cantaloupes. Further, LAB may minimize cross-contamination of Listeria at the postharvest level.