2018 ASHS Annual Conference

We worked with a retailer in Florida to perform in-store measurements of temperature distributions in open and closed-door refrigerated display cases for whole and fresh-cut vegetables. Complementary projects were conducted with retailers in California, Iowa, and New York. The collaborating retailer selected two stores of the same size and identical floorplans, with comparable sales volumes and customer demographics. Refrigerated display cases in both stores were instrumented with eight temperature and humidity dataloggers per display case, placed in the front and back of the top, middle and bottom shelves. Doors were then retrofitted onto the display cases in one store and data were collected over 23 weeks from April to September 2017. Samples of bagged baby spinach were collected on a biweekly basis from the two stores and assessed for product quality and microbial growth. Temperature uniformity was improved in the closed-door display cases. Temperatures in the front were found to be 2.2°C and 1.2°C higher than in the back for open cases, but only 0.7°C and 0.5°C higher for closed cases in fresh-cut and whole vegetable displays, respectively. There was greater variation among temperatures at the back of the cases than the front, but that variation was reduced by half in the closed-door displays versus open displays. Use of doors decreased the temperatures inside the display cases by about 3.0°C for fresh-cuts and 1.8°C for whole vegetables, actually necessitating adjustment of temperature settings by +0.8°C after retrofitting to avoid sub-zero temperatures. Saturated relative humidity was continuously recorded due to presence of free water from misting plus evaporation. Reduced energy consumption was also validated for display cases with doors. Assessments of product quality and microbial growth revealed no significant differences between baby spinach from open and closed-door display cases, likely due to the relatively short residence time of the product on display (<12 hours).