Mitigating Listeria monocytogenes and Salmonella populations on Field Packed Cantaloupe Contact Surfaces

During cantaloupe field packing cleaning and sanitizing food contact surfaces, like stainless steel packing tables and knives, are among the main control measures to prevent cross-contamination. Organic materials can build up on food contact surfaces throughout an operational day, impacting sanitizing efficacy. This study aimed to evaluate the efficacy of free chlorine (sodium hypochlorite; 150 ppm) and peroxyacetic acid (PAA; 80 ppm), at two contact times (30 min, and 15 h), against dry (∼5 log10 CFU/coupon) and wet (∼7 log10 CFU/coupon) inoculated cocktails of either Listeria monocytogenes and Salmonella, on clean and fouled stainless steel coupons (cm2). Inoculated untreated and water treated coupons were processed in parallel. Reductions of L. monocytogenes ranged from 0.5 ± 0.3 to >5.9 ± 0.0 [reached limit of detection (LOD)] and 0.4 ± 0.5 to >3.8 ± 0.0 (LOD) log10 CFU/coupon for wet and dry inoculation, respectively. Reductions of Salmonella ranged from 0.8 ± 0.3 to >5.9 ± 0.0 (LOD) log10 CFU/coupon for wet inoculation and from 0.9 ± 0.2 to >4.3 ± 0.0 (LOD) log10 CFU/coupon for dry inoculation. Except for L. monocytogenes on dry inoculated clean coupons held for 15 h, reductions in L. monocytogenes and Salmonella were significantly greater on coupons treated with Chlorine and PAA compared to untreated coupons, with nearly all sanitizer-treated coupons reaching the LOD. Reductions in both pathogens increased when contact time was extended and were greater when coupons were in a clean condition. Chlorine and PAA showed similar efficacy, with both achieving greater reductions than water alone. The most effective protocol for fouled surfaces was 15 h either chlorine or PAA, while 30 min sufficed for clean stainless steel; underscoring the need for thorough cleaning before applying sanitizers. These results offer valuable insights for the produce industry, aiding in data-driven decision-making regarding hygiene practices for stainless steel food contact surfaces. •Pathogen populations on fouled coupons were more resistant to sanitizer treatment•The addition of sanitizers increased population reductions•Extending sanitizer contact time increased pathogen reductions on fouled surfaces•Effective cleaning and sanitizing can reduce the risk of cross-contamination