Survival of Salmonella and Listeria monocytogenes on Food Contact Surfaces in Produce Packinghouses

Abstract

Short-season (90 d) produce packing operations may run double shifts with no clean breaks in between. This practice can result in produce contamination from food contact surfaces that are not cleaned and sanitized. Our study examined the survival of Salmonella and Listeria monocytogenes on polycarbonate, polypropylene, polyvinyl chloride (PVC), rubber, and stainless steel surfaces that contact produce in operations that have a short packing season. Coupons were spot-inoculated with five-strain cocktails of rifampicin-resistant Salmonella or L. monocytogenes (~7 log CFU/coupon), stored at 22 °C and 45–55% relative humidity, and enumerated at 0, 0.06, 0.25, 1, 2, 3, 7, 10, 14, 21, 30, 60, and 90 d. Significant differences were evaluated (p ≤ 0.05), and survival was modeled using linear and biphasic models. Salmonella reductions varied significantly by surface type, with rubber showing the greatest survival, followed by stainless steel at 90 d. In contrast, Salmonella concentrations on polycarbonate, polypropylene, and PVC were below the limit of detection at 90 d. L. monocytogenes reductions were not significantly different across materials at 90 d. Biphasic models better fit the inactivation of both pathogens. These findings highlight the importance of clean breaks and focusing interventions where pathogens demonstrate greater persistence in short-season packinghouses.