Minimizing pathogen growth and quality deterioration of packaged leafy greens by maintaining optimum temperature in refrigerated display cases with doors

Retail display of packaged fresh-cut leafy greens is a critical stage of cold chain management and is prone to temperature fluctuations when produce is displayed in open cases, due to infiltration of ambient air into the case. Previous studies demonstrated that retrofitting open display cases with doors is the most effective solution to bring produce temperatures into compliance with FDA Food Code (<5 °C), retain product quality longer, and reduce operational energy costs. In this study, we evaluated changes in quality attributes and populations of inoculated bacterial pathogens (Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes) in packaged baby spinach, chopped romaine, and lettuce mix displayed in a refrigerated case retrofitted with doors. All products displayed in the case with doors maintained high freshness and attractiveness after 3-day display, and the quality was comparable to that of products stored at a constant temperature in a 4 °C cold room. No substantial changes in pathogen populations were observed during the display period. These results demonstrate that retrofitting display cases with doors is a practical means of reducing temperature fluctuations and damage for fresh-cut products.