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United States Department of Agriculture

Agricultural Research Service


Location: Environmental Microbial & Food Safety Laboratory

2012 Annual Report

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.

3. Progress Report:
Two commercial scale retail display cases have been donated to the ARS by Hussmann Corp. The equipment is now installed and operational at our ARS facility, and several objectives have already been achieved. The first goal of this project was to examine and modify the operational parameters of the open-refrigerated retail display cases to maintain compliance with the FDA regulations regarding holding temperatures for fresh-cut produce (below 41 degree Fahrenheit, FDA FOOD CODE). This objective was accomplished through manipulation of 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). Produce managers in retail stores routinely perform internal audits of their equipment thermostat settings and product temperatures as determined by instant-read non-contact thermometers. ARS has determined, through this research project, that the commonly-used infrared thermometer technology is not an appropriate method for determining the product temperature of bagged leafy-greens. ARS findings have been very well received by both industry stakeholders and regulatory agencies that frequently find temperature abuse at retail for foods that fall under the new FDA Food Code temperature requirements.

4. Accomplishments

Last Modified: 08/15/2017
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