A home-type refrigerator was used to determine the time of exposure of foods of varying solids content to temperatures suitable for microbial growth. The foods were handled using standard recommended public health procedures. Samples were tested with and without supplementary air circulation. The total time in the temperature range of 140 F to 45 F varied from 13 h to over 22 h. Supplementary air circulation had little benefit in reducing cooling times when used indirectly, i.e., when directed away from the test foods at the bottom of the refrigeration compartment. However, when the supplementary air was directed on the test foods from a distance of 4 inches, the cooling time was reduced by approximately one-half. The time of food exposure to a temperature range most favorable to microbial growth (100 F to 70 F) exceeded 5 h without supplementary direct air circulation, but was reduced to less than 2 1/2 h with direct forced air supplementary circulation. Alternate techniques to reduce the temperature of foods to supplement mechanical refrigeration are also discussed.

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Author notes

1TravisAir Force Base.

2College of Marin.