Temperature profiling of open- and closed-doored produce cases in retail grocery stores

Temperature control of produce in the retail environment is essential to reduce food safety risks, maintain quality, and reduce food waste. Previous studies have demonstrated that retrofitting or replacing open display cases doors results in better control of temperature and humidity. However, there are no studies to date that comprehensively evaluate temperature profiles in cases with and without doors in actual retail store environments. Twenty-five open and closed refrigerated display cases in ten retail stores in five states were monitored for temperature and humidity over 9 months. Sensors recorded data every 2 min at eight positions (top, middle, bottom and under the bottom bin, in the front and back locations of each shelf). There were significant differences between open and closed cases, retailers, and sensor position in display cases on temperature and relative humidity (p < 0.0001). Seven display cases were retrofitted with doors and, as a result, temperature variations were significantly minimized (p-value < 0.0001). Cases with doors maintained temperatures significantly lower (4.7 degrees C, p-value < 0.0001) than cases without doors, and the top front position in the cases had both the highest temperature (5.7 degrees C) and abuse due to high temperature ( > 5 degrees C) for the longest duration (35.7% of total time observed) of allow locations measured. Temperatures and abuse conditions above 5 degrees C were not significantly different between front and back positions in the cases. The range of temperature and RH variability was reduced following door installation. With changes in display case technology over the past five years, this study provides updated data on operational temperatures in display cases before and after retrofitting with doors. It also provides evidence of the importance of temperature monitoring within display cases to ensure abusive conditions do not persist.