Maintaining proper storage temperature is critical for ensuring the quality and safety of fresh-cut products. The US Food and Drug Administration Food Code recommend that packaged fresh-cut leafy green vegetables be kept no warmer than 5C at all times to ensure food safety. Substantial temperature variations, however, within the widely used open refrigerated display cases used in retail stores are known to present the technical challenge of complying with this federal guidance for industry.

Product temperature profile
Product temperature profile

Packaged fresh-cut vegetables are popular food products as they are convenient, healthy, and ready-to-eat. Due to increased consumer demand, the fresh-cut produce industry has been rapidly expanding. However, fresh-cut produce has limited shelf stability due to rapid product quality deterioration. Advancements in freshcut packaging technologies have enabled the industry to maintain quality for longer periods of time.

The ability to maintain recommended storage temperatures of these fresh-cut products is vital to ensure optimal food quality, and extended product shelf life.

Storage temperature is an important factor affecting the growth of spoilage and pathogenic bacteria. Studies showed that Escherichia coli O157:H7 grows rapidly in temperature-dependent manner on bagged fresh-cut leafy green products. The US Food and Drug Administration (FDA, 2009) revised the Food Code to include packaged fresh-cut leafy greens in the “temperature control for safety” (TCS) food category, and recommended that these products be maintained at 5 C or below in transport, storage and retail display. This has also been adopted in the 2013 version of the Food Code.

Open-refrigerated display cases are widely used in supermarkets and grocery stores as a primary means to provide the cold temperature necessary for the proper storage of fresh and fresh-cut produce. Although these cases have the visual benefit of being aesthetically pleasing with concomitant easy access by consumers, they are not energy efficient and often fail to provide the temperature necessary for proper storage of the packaged fresh-cut fruits and vegetables.

Furthermore, temperature profiles in commercial retail displays showed large variations depending on the location of the produce in the displays.These surveys reinforce the fact that retail display cases represent a weak link in the maintenance of a proper cold chain management.

The highly variable temperature conditions associated with the storage of fresh-cut products in commercial open-refrigerated display cases dramatically affect the quality and safety of produce suggest that research-based time range estimates for retail storage and accurate correlations between time and temperature during retail storage are needed, and the importance of this lag time in modeling E. coli O157:H7 growth in leafy greens is currently unknown.

A technical challenge of open display cases is to keep products in the front rows below 5 C and products in the back above freezing. Thermostat setting, room temperature and HVAC systems are factors that affect product temperatures inside the open case.

Although changing case duty cycle could increase or decrease product temperatures, lowering the case thermostat setting would lead to the potential for freezing damage, while increasing thermostat setting may increase the risk of high temperature abuse and violation of the FDA Food Code.

To alleviate these problems related to temperature abuse and freezing damage, retailers have been frequently rotating the products from front to back and back to front. However, those practices are labor intensive and costly. Foam blocks are a good alternative to this problem, and we demonstrated their effective insulation in the display case, however, these may not be suitable for commercial display case installation. Presently, the number of retail stores installing night curtains or transparent doors is increasing. The installation of curtains and doors would not only decrease the amount of warm air coming in from the aisle, but also retain the cold air coming from the back of the display case, and thus reduce energy costs. Studies conducted by the U.S. Department of Energy (DOE) showed that for open refrigerated display cases, infiltration loads comprise 70e80% of the total case heat load. For comparison, in display cases manufactured with vertical transparent display doors that are operating in a similar configuration, the infiltration accounts for roughly 10% of the heat load to be removed from the display case.

Our PIMM™ Analytics (AI engine) system has access to all of the product data throughout the distribution process. The storage and shipment data is analyzed by our AI engine in PIMM™ PPT – it is then re-analyzed with the product specification and traceability data to determine the number of “Lost Days” of shelf Life. The last calculation is to apply the number of “Lost “Days” to the “Sell by Date” which will determine the new Estimate Shelf Life Date.

To learn more about this and other PIMM™ Products, please visit us at or call TOLL FREE today 1-888-571-PIMM (1-888-571-7466)!

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