A Comprehensive Evaluation of Temperatures within Home Refrigerators

Abstract

SUMMARY Microbial growth in many foods can be controlled by proper refrigeration. Thus, it is recommended that refrigerators be maintained at 40 o F (4.4°C) or below. However, no recent extensive studies have been reported that assess actual temperatures at which cold foods are stored over time within the home. The objective of this project was to evaluate the temperatures of refrigerators in 200 homes in the United States. Loggers were used to record temperatures each minute in several locations in each refrigerator. In some homes, a thermocouple was also placed in a commercially sealed hot dog and in a cup of yogurt. Data were analyzed using Excel and SPSS-PC. Mean temperatures were 35.5, 38.0 and 41.3oF (1.9, 3.3 and 5.2°C) for the top shelf, bottom shelf and door, respectively, with 9, 25 and 61% of these areas having average temperatures above 40oF (4.4°C). Over 66% of refrigerator door temperatures were above 40oF (4.4°C) for more than eight hours per day. The temperature of the foods fluctuated less than the temperature of the surrounding air. Temperatures rose above the danger zone (above 40oF or 4.4°C) for more than 2 hours a day for 33%, 45%, and 80% (top shelf, middle shelf, door, respectively) of refrigerators. Consumers need to check the temperature regularly and should be advised to store temperature-sensitive foods on the top shelf of the refrigerator when appropriate.