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Listeria monocytogenes (L. monocytogenes) biofilm formation on food-contact surfaces is a significant food safety concern. However, research on the ability of contact surfaces to resist fouling by L. monocytogenes biofilm is limited. With the objective of assessing the combined effects of substrate topography and coating composition on L. monocytogenes biofilm formation, we used stainless steel 304 with three surface topographies (native finish, #4 commercial brushed finish, and native finish with microfabricated pillars developed by a new process), in each case either uncoated or coated with one of five FDA-approved food-contact substances (chromium nitride, titanium nitride, Dursan, Ni–P-polytetrafluoroethylene (Ni–P-PTFE), and Lectrofluor 641). Results indicate that surface topography and composition significantly affected fouling resistance. Significant enhancement of resistance to L. monocytogenes fouling was observed on native finish coated by Ni–P-PTFE, which reduced L. monocytogenes by 1.5 Log CFU/cm2. Coating the brushed finish with Ni–P-PTFE, Lectrofluor 641, or Dursan reduced L. monocytogenes fouling by 0.5, 0.4, and 0.9 Log CFU/cm2, respectively. The greatest reductions in L. monocytogenes biofilm formation were obtained with Dursan coated on the native finish (3.4 Log CFU/cm2) and on the micropillar-modified native finish (2.8 Log CFU/cm2). The combined variation of substrate topography modification and coating composition provides a new approach to enhance fouling resistance of stainless steel against L. monocytogenes biofilm for improved sanitary design of food processing equipment. • Nonfouling enhancement of stainless steel against Listeria monocytogenes biofilm. • Combination of topography modification and food contact substances (FCS) coating. • Dursan coating demonstrates the strikingly good fouling-resistant effect. • The new strategy can be applied for improved food processing equipment design. [ABSTRACT FROM AUTHOR]

Retail display of highly perishable foods behind glass doors ensures uniform product temperatures below the FDA Food Code threshold of 5 °C, resulting in better-preserved foods while reducing energy costs. However, only a handful of studies have evaluated the effect of repeated door openings on product temperatures and energy consumption with contrasting reports. In this paper, we evaluated the effects of two frequencies (doors opened every 5 or 15 min) and four durations (doors held ajar for 5, 15, 30 or 60 s) on product simulator temperatures in a display case installed in our research supermarket. At ambient conditions (19.6–20.9 °C, 63% RH), with a case thermostat setting of 0.6 °C and a daily 30-min defrost cycle, the only statistically significant fluctuation in product simulator temperatures was found for the most aggressive opening schedule where the door was opened every 5 min for 60 s at each opening. Pairwise comparisons demonstrated that this treatment resulted in product simulator temperatures (up to 6.6 °C during defrost cycle) that were significantly higher (p < 0.001) or somewhat significantly higher (p < 0.03) compared to product exposed to all other combinations. Product exposed to all other treatment combination resulted in temperatures that either never exceeded 5 °C or briefly exceeded it only during the single 30-min defrost cycle. As a result, we selected an average opening sequence (every 10 min for 12 s) to perform an energy consumption assessment of the case. Energy consumption was determined to be 66% lower than that compared to an open-retail display case (same model, mark, size, operating schedule and thermostat setting). Even with the most extreme schedule where three of the six doors remained open continuously, there was still a measured 45% reduction in energy consumption as compared to that of the open-retail display case. • Enclosed refrigerated display cases support compliance with US Food Code. • Typical door opening regimes do not impact product temperature uniformity in display cases. • Typical door opening regimes still provide significant energy savings compared to an open display case. [ABSTRACT FROM AUTHOR]