Mary Engle Pennington Tracks the Cold

Written by Studio AM.

Mary Engle Pennington treated refrigeration as a continuous journey rather than a single cold room. Born in 1872, she studied chemistry and biology at the University of Pennsylvania. Women then received certificates rather than bachelor's degrees there, but she earned a doctorate in 1895. After running a clinical laboratory in Philadelphia, she joined the United States Department of Agriculture in 1905 as a bacteriological chemist.

Following the 1906 Pure Food and Drugs Act, Pennington became chief of the new Food Research Laboratory. Her team studied perishable foods and compared temperature conditions with bacterial growth and visible deterioration. Their work showed why foods needed steady cold, not cooling at isolated moments. Pennington followed the practical problem through storage, handling, transportation, and distribution. A well-cooled warehouse could not protect an egg that warmed elsewhere on its route.

The work joined laboratory evidence to ordinary equipment and routines. She examined containers and transport conditions and insisted that freshness claims be measured. Maintaining that continuity required engineers, drivers, warehouse workers, inspectors, and many others.

After leaving federal service in 1919, Pennington continued work on food preservation and later on frozen foods. Her work made each transfer part of the refrigeration problem: food needed suitable temperatures in transit as well as in storage. By making the gaps between facilities part of the scientific question, she helped turn refrigeration from a collection of cold places into a connected system.

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  1. Question 1 of 4

    What is the main idea of the passage?

  2. Question 2 of 4

    Why does the author describe refrigeration as a chain?

  3. Question 3 of 4

    What does “perishable” mean as used in the passage?

  4. Question 4 of 4

    What position did Pennington take in 1905?

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