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.

Raw and minimally processed berries are not subjected to any processing kill steps and are stored under cold conditions to extend shelf-life. This study evaluated the growth and survival of high and low populations of L. monocytogenes on blueberries and raspberries stored under refrigerated and frozen temperatures. Fresh berries (10 g) were inoculated with a five-strain cocktail of L. monocytogenes to target 5.5 or 2 log CFU/g, stored at 4 and −18 ± 2 °C, and enumerated for up to 14 days post inoculation (dpi) at 4 °C and 168 dpi at −18 °C. Significant differences were evaluated (p ≤ 0.05), and die-off was modeled, using Davies test to determine breakpoints. No significant changes (p > 0.05) in L. monocytogenes populations were observed over time on berries stored at 4 °C, regardless of inoculation level. At −18 °C, significant reductions were observed over 168 dpi, with greater declines for high-inoculated blueberries and raspberries (2.63 and 2.13 log CFU/g, respectively), compared to those that were low-inoculated (0.67 and 0.46 log CFU/g, respectively). Die-off modeling indicated linear decay for both low-inoculated berry types and biphasic patterns for both high-inoculated frozen blueberries and high-inoculated raspberries stored at 4 °C. Results suggest that while L. monocytogenes does not grow, blueberries and raspberries support survival during refrigerated and frozen storage, emphasizing the need for stringent pre- and postharvest practices to limit contamination.