Consumer Storage Practices and Their Impacts on Microbial Safety of Home Refrigerated Foods

Introduction: Studies have shown that consumers often failed to follow the recommended guidelines for proper storage of refrigerated foods at home. However, the relation of improper refrigeration practices and microbiological contamination of refrigerated foods has not been fully assessed.

Purpose: The objective of this study was to identify risk factors for microbial contamination related to storage practices of refrigerated foods.

Methods: In-home interviews and observations were conducted in seventy homes in Nashville, Tennessee. A total of three hundred and twenty samples were collected from participants’ refrigerators during home visits. Swab samples were taken from shelf surfaces in the refrigerators and food samples (including home prepared foods, leftovers, and opened packages of ready-to-eat foods) were collected from the participants’ refrigerators. Microbiological analyses were performed and molecular fingerprints of Staphylococcus aureus (SA), and Bacillus cereus (BC) were studied using Pulsed Field Gel Electrophoresis (PFGE).

Results: Eighty-four percent of the observed leftover containers were covered, but only 3.3% of the leftovers had a date labeled. When asked about how long the leftovers were in the refrigerator, 20.5% answered longer than two weeks and 38.5% did not know. Microbiological analyses indicated refrigerator shelf surfaces were often contaminated with high level (more than 10³ CFU/100cm²) of SA (15.7%) and BC (22.1 %). Significant numbers of food samples contained high level (more than 10³ CFU/g) of SA (13.9%) and BC (16.7%). Of the 180 food samples, two of SA and five of BC contamination in refrigerated foods belong to the same PFGE type from the refrigerator shelf surfaces where the foods were stored.

Significance: The results suggested poor sanitation condition and prolonged storage were the most significant factors that affect microbiological safety of home refrigerated foods.