Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #298126

Title: Open-refrigerated retail display case temperature profile and its impact on product quality and microbiota of stored baby spinach

item KOU, LIPING - Northwest Agriculture And Forestry University
item Luo, Yaguang - Sunny
item INGRAM, DAVID - Food And Drug Administration(FDA)
item YAN, SHOULEI - Huazhong Agricultural University
item Jurick, Wayne

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2014
Publication Date: 8/5/2015
Publication URL:
Citation: Kou, L., Luo, Y., Ingram, D., Yan, S., Jurick II, W.M. 2015. Open-refrigerated retail display case temperature profile and its impact on product quality and microbiota of stored baby spinach. Food Control. 47:686-692.

Interpretive Summary: Storage temperature is a critical factor influencing the quality and safety of packaged fresh-cut leafy green vegetables. USDA-ARS Scientists at the Beltsville Agricultural Research Center evaluated the temperature profiles, product quality, and microbial growth of ready-to-eat baby spinach located in different positions (shelf height, depth) under various conditions in a commercial open-refrigerated display case operating under standard temperature conditions. Results from this study indicate that the observed temperature differential between the front and back of the case significantly reduced product quality and shelf life. However, blocking the heat transfer from the ambient warm air to the cabinet led to a significant improvement in the temperature uniformity. This study provides critical information to stakeholders and manufacturers to redesign and or modify existing equipment with improved temperature control features for maintaining food quality and safety while simultaneously reducing energy costs.

Technical Abstract: Open-refrigerated display cabinets are widely used in supermarkets and grocery chains around the globe. However, the temperature conditions in these display cases are variable which may impact product quality and safety. Therefore, we investigated the quality and microbiological populations of bagged baby spinach for 3 days at different positions within a commercial display case. Results from this study shows that significant temperature profiles occurred within products on the same shelf and at different depths. Baby spinach located near the back of the case had signs of low temperature damage and decreased quality. However, spinach at the front of the case was yellow, dehydrated, had high electrolyte leakage, and elevated microbial counts. In order to reduce the temperature variation, a number of technical enhancements were tested. Insulating foam boards, when installed in front or in the front-and-back of each shelf, significantly decreased the temperature variation by 4 - 5 °F, resulting in better overall temperature control. These results suggest that mechanical modification (i.e. like the addition of a curtain or glass door) to the display-case will provide better temperature homogeneity and thus maintain product quality and safety of bagged products during retail display.