Mary Engle Pennington(1872 — 1952)
Mary Engle Pennington
États-Unis
6 min read
Mary Engle Pennington (1872-1952) was an American chemist, bacteriologist, and engineer, a pioneer of food preservation through refrigeration. She established the scientific standards of the cold chain for milk, eggs, and poultry in the United States.
Frequently asked questions
Key Facts
- 1895: earned a doctorate in chemistry from the University of Pennsylvania at a time when women rarely graduated from the institution
- 1907: became the first woman to head a laboratory within the U.S. Department of Agriculture (the food laboratory of the Food Research Laboratory)
- Established the scientific standards for cold preservation of milk, eggs, and poultry
- 1919: received the Notable Service Medal from President Herbert Hoover for her work during the First World War
- 1940: first woman inducted into the American Society of Refrigerating Engineers
Works & Achievements
A rare degree for a woman at the time, which launched her scientific career.
An institution she founded and directed, where she developed methods for analyzing food safety.
A framework adopted by Philadelphia and then other cities, helping to reduce illnesses linked to contaminated milk.
The first woman to head this federal laboratory, where she founded the science of cold preservation.
A set of temperature and hygiene standards that permanently transformed the American food industry.
Design of better insulation and improved cold ventilation for transporting perishable goods.
An authoritative reference work on the freshness and preservation of eggs.
Posthumous recognition of her role as a pioneer of food refrigeration.
Anecdotes
In 1892, the University of Pennsylvania refused to grant Mary Engle Pennington a bachelor's degree because she was a woman: instead, she was handed a mere “certificate of proficiency.” Far from discouraged, she continued her studies and earned a doctorate in chemistry by 1895, at just 22 years old.
To sit the federal civil service examination, Mary signed her application “M. E. Pennington,” without revealing her first name. The examiners, convinced they were dealing with a man, hired her: only afterward did they discover that their brilliant candidate was a woman.
To understand why food spoiled during transport, Pennington thought nothing of climbing into the refrigerated cars of freight trains herself to measure the temperatures inside. Her observations made it possible to design better-insulated, better-iced cars, the ancestors of our modern cold chain.
A recognized authority on the egg, she perfected “candling”: by holding an egg up to a lamp, one can see through it whether it is fresh or spoiled. Her recommendations on the handling of eggs and poultry became standard references throughout the American food industry.
Her pioneering work was recognized long after her death: in 2018, Mary Engle Pennington was inducted into the United States National Inventors Hall of Fame, alongside the greatest inventors, for having built the scientific foundations of food preservation by refrigeration.
Primary Sources
A reference work in which Pennington synthesizes decades of research on the freshness, preservation, and marketing of eggs, from producer to consumer.
Official documents written under Pennington's direction, establishing the temperature and hygiene conditions for the collection, storage, and refrigerated transport of perishable goods.
Bacteriological standards developed by Pennington to assess the safety of milk, later adopted as a model by other American cities.
Pennington's doctoral work in chemistry, which opened the way to a scientific career then largely closed to women.
Key Places
Birthplace of Mary Engle Pennington in 1872.
The city where she grew up, studied, and began her career; here she founded her laboratory and developed the standards for milk inspection.
The institution where she earned her doctorate in chemistry in 1895, despite being denied a bachelor's degree.
Headquarters of the Department of Agriculture, where she led the Food Research Laboratory from 1908 onward.
The city where she worked as a refrigeration consultant and where she died in 1952.