Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #318380

Title: Lower temperatures in cases with doors improve produce quality and safety with reduced energy consumption

item DE FRIAS, J. ATILIO - University Of Maryland
item Luo, Yaguang - Sunny
item ZHOU, BIN - University Of Maryland
item Turner, Ellen
item Millner, Patricia
item Nou, Xiangwu

Submitted to: Produce Business
Publication Type: Trade Journal
Publication Acceptance Date: 7/15/2015
Publication Date: 8/12/2015
Citation: De Frias, J., Luo, Y., Zhou, B., Turner, E.R., Millner, P.D., Nou, X. 2015. Lower temperatures in cases with doors improve produce quality and safety with reduced energy consumption. Produce Business. 31(8):14.

Interpretive Summary: Product temperatures at the front of refrigerated, open-display cases used for fresh-cut and packaged ready-to-eat leafy greens often exceed the FDA Food Code temperature requirement. This issue cannot simply be solved by lowering thermostat settings, as reduced temperatures in the front would come at the expense of frozen products in the back of the case. USDA-ARS scientists at the Beltsville Agricultural Research Center evaluated many options for improving temperature uniformity and product quality, and demonstrated that the installation of clear glass doors on refrigerated fresh-cut produce cases was the most cost-effective solution to this problem. The solution enables compliance with the FDA Food Code with consistently low, yet above freezing temperatures throughout the display case. Products on display following the Food Code recommendations also lasted longer, with fewer quality defects, and no significant growth of human pathogens. In addition, operational energy costs were up to 69% less than those for refrigerated open-display cases. This study empowers fresh-cut processors and retailers with scientific information to improve product quality and safety, and reduce operational energy costs during retail display of fresh-cut produce.

Technical Abstract: Time-temperature control of fresh-cut produce at 41 °F (5 ºC) or less can significantly reduce the growth of human pathogens. Since 2009, the FDA Food Code has required that packaged ready-to-eat leafy greens be kept at 41 °F (5 ºC) or lower to minimize the potential of pathogen proliferation in the supply chain. Under commercial settings, scientific studies have reported large temperature variations and temperature abuse for produce displayed in open multi-deck refrigerated cases, often exceeding 41 °F (5 ºC) in the front rows. These conditions may expose products to an increased risk for pathogen growth and reduced produce quality, while the retailer incurs increased energy costs as a result of the high cooling load from the infiltration of warm ambient air into the case. Lower product temperatures in open cases are not achieved by simply lowering thermostat settings, because freezing temperatures and loss of product quality can occur in the rear sections of the cases. To address these issues, we examined several options in our research supermarket facility at the USDA Agricultural Research Service (ARS), including the use of insulators and heat storage materials inside the display cases, as well as the installation of curtains and doors. The installation of clear glass doors was determined as the most cost-effective solution.