1a.Objectives (from AD-416):
The objective of this cooperative research is to facilitate evaluation of new designs and operations of refrigerated retail display cases as part of a series of food safety technologies and interventions.
1b.Approach (from AD-416):
A range of temperature control sequence options and shelf modifications will be used to evaluate growth of E. coli in packaged fresh-cut leafy greens, produce quality, and shelf-life. Non-pathogenic E. coli will be inoculated onto fresh leafy green produce or cut/shredded then inoculated. The product will be packaged, treated with modified atmosphere, subjected to simulated storage/transport, and placed in refrigerated retail display conditions for evaluation of E. coli survival. Cells of E. coli will be recovered from produce and quantified using standard plating or enrichment procedures.
Excellent progress has been made in this project. Two commercial scale open refrigerated retail display cases were donated by Hussmann Corp. The ARS team examined the operational parameters of the open cases to determine if they were in compliance with the FDA regulations regarding holding temperatures for fresh-cut produce at below 41oF without freezing the products. The team also evaluated the options of manipulating both the equipment duty cycles (defrost schedules, thermostat settings) and optimization of retail management practices (produce location within each shelf, stock rotation schedules and case shelving material). We reported that the large temperature variations between products located in the front row (warmest) and back rows (coldest) within the case were the major problem impeding compliance with the FDA food code, and that the current open case design is not energy efficient. In working closely with the Hussmann team, doors and night curtains were installed on the cases. Preliminary testing results show that the doored and curtained cases have much less temperature variation, and are more energy efficient. Additional evaluation on produce quality and safety is ongoing.