Salmonella and Listeria monocytogenes survival on Field Packed Cantaloupe Contact Surfaces

Claire M Murphy; Loretta M Friedrich; Laura K Strawn; Michelle D Danyluk

doi:10.1016/j.jfp.2024.100299

Salmonella and Listeria monocytogenes survival on Field Packed Cantaloupe Contact Surfaces

J Food Prot. 2024 May 9:100299. doi: 10.1016/j.jfp.2024.100299. Online ahead of print.

Authors

Claire M Murphy¹, Loretta M Friedrich², Laura K Strawn³, Michelle D Danyluk²

Affiliations

¹ School of Food Science, Washington State University - Irrigated Agriculture Research and Extension Center, Prosser, WA, USA.
² Department of Food Science, University of Florida - Citrus Research and Education Center, Lake Alfred, FL, USA.
³ Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA.

PMID: 38734412
DOI: 10.1016/j.jfp.2024.100299

Abstract

Field-packing of cantaloupes involves numerous food contact surfaces that can contamination melons with foodborne pathogens; the soil on these surfaces increases throughout the harvest day. Data is lacking on the cross-contamination risk from contaminated food contact surfaces under the dry conditions typical of cantaloupe field-packing operations. This study sought to evaluate the survival of Salmonella and Listeria monocytogenes on cantaloupe field-pack food contact surfaces using both a wet and dry inoculum to provide insights into managing foodborne pathogen contamination risks. Five clean or fouled materials (cotton gloves, nitrile gloves, rubber gloves, cotton rags, and stainless steel) were inoculated with a cocktail of either Salmonella or L. monocytogenes. A wet inoculum was spot inoculated (100 µL) onto coupons. A dry inoculum was prepared by mixing wet inoculum with 100 g of sterile sand, and shaking the coupons with the inoculated sand for 2min. Coupons were held at 35°C (35% RH) and enumerated at 0, 2, 4, 6 and 8 h. Significant differences in pathogen concentrations over time were calculated and the GInaFiT add-in tool for Excel was used to build Log-linear, Weibull, and Biphasic die-off models. Depending on the material type, coupon condition, and inoculum type, Salmonella and L. monocytogenes reductions over 8 h ranged from 0.3-3.3 and -0.4-4.2 log₁₀ CFU/coupon, respectively. For all material types, Salmonella reductions were highest on wet-inoculated clean coupons; L. monocytogenes varied by material type. Weibull and biphasic models were a better fit of respective pathogen die-off curves than linear models. Overall, faster die-off rates were seen for wet inoculated and clean materials. Since pathogen populations remained viable over the study duration and both inoculum type and coupon condition impacted survival, frequent sanitation or replacement of food contact surfaces during the operational day is needed to reduce the risk of cross-contamination.

Keywords: Food Contact Surfaces; Fouled; Listeria monocytogenes; Salmonella; Survival; dry inoculum.