Improving temperature management and retaining quality of fresh-cut leafy greens by retrofitting open refrigerated retail display cases with doors

• Published in: Journal of food engineering Vol. 292; p. 110271
• Main Authors: Xie, Yurui, Brecht, Jeffrey K., Abrahan, Carolina E., Bornhorst, Ellen R., Luo, Yaguang, Monge, Ana Lorena, Vorst, Keith, Brown, Wyatt
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2021
• Subjects: Baby spinach; Chopped romaine quality; Lactuca sativa L. var. longifolia; Refrigerated display cases with doors; Spinacia oleracea; Spring mix; Spinacia oleracea; Baby spinach; Spring mix; Refrigerated display cases with doors; Chopped romaine quality; Lactuca sativa L. var. longifolia
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2020.110271

Open refrigerated display cases in supermarkets are prevalent in the United States despite being prone to temperature fluctuations. We collaborated with a chain retailer in Florida to retrofit existing open vegetable display cases with doors, and monitored the display temperature profile over 5 months. Quality evaluations were performed on baby spinach, spring mix, and chopped romaine lettuce after storage under simulated open and closed case conditions. Doors improved spatial and temporal temperature uniformity in whole and fresh-cut vegetable cases. Optimal storage temperature for ready-to-eat produce (≤5 °C) was recorded over 98% of the time after door installation versus 49–88% before retrofitting. An overall temperature decrease in the fresh-cut produce case from 3.62 to 0.66 °C necessitated a thermostat setting adjustment of +1.1 °C to avoid freezing of salad product. Elevated headspace CO2 concentrations and higher populations of aerobic bacteria (6.6 log CFU g−1), yeasts and molds (4.6 log CFU g−1) were found under open display conditions for one or more salad products tested. Baby spinach leaves from the open case environment were lighter green and more yellowish in color. Electrolyte leakage and ascorbic acid content of the three salad types were similar between the open and closed door displays. Superior overall visual quality and stronger purchase intent were found for baby spinach and spring mix samples from the closed display case. These products had less severe off-odor and discoloration, and crispier texture than those held in the open case. The decreased overall temperature and improved temperature uniformity in closed display cases, along with better produce quality and potential energy savings, may encourage retailers to consider retrofitting open displays with doors or purchasing closed displays.
•Enclosing produce displays improved spatial and temporal temperature uniformity.•The lower temperature reduced respiration and better retained leafy greens quality.•Populations of aerobic bacteria and yeasts and molds on chopped romaine were lower.