Our Newsletter to your inbox every week!
“Underfeeding will make a coward of a nation,” Dr. Mary Pennington announced at the National Poultry, Butter and Egg Association conference in Chicago in October 1917. “A hungry man may rise to a moment of valor, but when a whole people are hungry, they become moral and physical weaklings.” At the time Dr. Pennington made this statement she was serving as chief of the food research laboratory of the United States Department of Agriculture. America had entered the first World War six months prior to the conference in Illinois, and Mary was on a mission to encourage the country’s farmers to increase shipments of poultry, eggs, and fish. “The supply of beef is not enough to go around and the deficit must be made up with other food,” the October 19, 1917, edition of The Leavenworth Times reported the doctor as saying. “We must feed our men in the trenches and the men of our allies. We must also feed the civilians of our own country and those of our allies.”
Mary’s goal was sound, but the method for transporting meat and produce from one part of the United States to the other without those goods going bad had not yet been perfected. She would spend the next six years working with railroad companies developing the modern refrigerator boxcar.
Mary Engle Pennington was born in 1872 in Nashville, Tennessee. Her parents were Quakers who showered their children with attention and nurtured their academic talents. Mary’s interest in chemistry came about after reading one of her father’s books. She knew early in her life she would pursue a career in the field. She entered the University of Pennsylvania in Philadelphia in 1890 with the idea of acquiring a degree in science. Women pursuing a higher education was a relatively new notion. Despite of the fact that the university did not grant degrees to women, Mary completed her coursework, receiving high marks in every subject. Officials at the school awarded her a proficiency certificate in chemistry, zoology, and botany. Mary continued with her studies, earning the respect of the board of trustees who decided to bestow her with an advance Ph.D. in 1895.
From 1897 to 1899, she researched physiological chemistry at Yale. Before she ended her time at the Ivy League institution, she accepted a position as the Director of the Clinical Laboratory with the Women’s Medical College of Pennsylvania. During that same period, Mary also served as bacteriologist with the Philadelphia Bureau of Health and worked for the Pennsylvania Department of Hygiene. During her time with the government agencies, she successfully raised sanitation standards for the handling of milk and milk products.
The research and published findings that came about as a result of Mary’s work on bacteria toxicity levels in dairy products caught the attention of Harvey Wiley. Wiley was a chemist and head of the U. S. Department of Agriculture who believed strongly that the country needed to have food safety standards. He had dedicated his efforts to determining what, if any, hazardous effects resulted in adding coloring matter and preservatives to foods and canned goods specifically. Dr. Wiley’s work created problems for canning factories where vegetables, fruits, and meats were put up for table use and formed the chief winter diet for a large part of the people of the United States in the early 1900s.
In 1905, Dr. Wiley offered Mary a job on his “poison squad”. The squad was made up of like-minded chemists and botanists interested in the idea that consumers should expect the food they purchased to be pure and not filled with chemicals. Wiley believed Mary’s vast knowledge about agricultural products in cold storage would greatly benefit the department. Mary joined the team, and their combined discoveries prompted political leaders to approve the Pure Food and Drug Act of 1906. The act forced food manufacturers to list all the ingredients of the product on the package and prohibited the use of ingredients known to be deleterious to human health.
Not long after the passage of the act, Dr. Wiley asked Mary to head the Bureau of Chemistry’s Food Research Lab. In anticipation that the hiring of a woman to such a lofty title might not be well received, Dr. Wiley presented Mary’s resume, under the name of M. E. Pennington, and credentials to the executive who reviewed potential civil service employees. Mary was hired. Her job was to help implement the Pure Food and Drug Act. Under her leadership, the laboratory conducted pioneering research leading to the recognition that fresh foods could keep much longer without spoiling when they were kept at low temperatures.
In a presentation given to the Warehouseman’s Association in Washington, D. C., on October 3, 1908, Mary explained the importance of cooling fruits immediately upon being picked and warned the association that all food products should be merely cooled and kept cool and not frozen. She demonstrated that freezing food products caused chemical changes that materially altered the nature of the product. She also discussed the cooling of milk and butter and showed that the careful manufacture in the latter was of equal importance to care in transportation.
A cold storage boxcar, built under the direction of the Agricultural Department, was exhibited at the conference, and Mary gave a detailed explanation of the capabilities of the car. “This unit can create a temperature of fifteen degrees below zero and is intended to be used at fruit groves in cooling off the fruits as they are picked in order that they may get to market in perfect condition,” the December 4, 1908, edition of the Washington Post quoted her at the Warehouseman’s Association. The car was scheduled to be sent to California to be tested by actual use in the orange and lemon groves during the harvest season and then taken to Florida. Mary would travel with the car and carry out experiments along the way.
The first refrigerated boxcars, or “reefers” as they were called, became part of the railroad’s rolling stock in the late 1860s. Early designs featured metal racks that extended across the width of the car in which beef and pork were hung above a frozen mixture of ice and salt. The design was improved upon in 1875. Huge blocks of ice were packed into cars, and additional ice was added along the route via hatches in the roof. Hay and sawdust were packed around the ice to give it added insulation. Screen slats on opposite sides of the hatches on the roof provided the necessary ventilation. The train’s motion circulated the cool air throughout the cargo space. Meat and produce shipped across country risked contamination and mold using those inefficient, rudimentary refrigerator cars. Mary was convinced that improvements made to the refrigerator boxcar would keep perishable food making its way from once coast to the other from rotting. Inventing such a mechanism would help farmers and livestock growers increase their business, enable railroad companies to expand their lines, and keep consumers of these goods and services healthy.
In addition to working on designing a refrigerator boxcar, Mary was tasked with educating the public about the benefits of cold storage. Housewives across the country in 1910 were opposed to buying frozen foods, particularly poultry. The prevailing thought was that the product wasn’t fresh. Whenever they did purchase a frozen chicken, most women were placing it in water or leaving it outside in a pan to thaw. That action contaminated the food and made people who ate the chicken sick. The recommended thawing process was to take place in a home refrigerator over a period of time.
“No housewife can afford nowadays to remain in ignorance of what has happened to her chicken before she buys it,” Dr. Pennington explained in an article entitled “A Woman’s Work for Pure Storage Food”, in the March 20, 1910, edition of The Oregon Daily Journal. “What will happen afterwards is too direct a consequence of what has happened previously. The investigation which began with the study of poultry in cold storage, developed the impressive, guiding fact about four years ago that the condition of poultry when it came out depended largely on its condition when it went in.
“Every detail in the handling of perishable food products is important, and the underlying principles was the same whether storage is dealing with an apple or a carload of chicken. The chicken that is exhibited to the marketing housewife on the butcher’s stall is a chicken, it is true, but it is most likely not to be the particular era of chicken that is seems. And between the period when it was a live chicken and the period when it makes its public debut as dead, one of the fates of many elements have worked their will upon it.
“For some of its mischances, the housewife herself is responsible. It is therefore fitting that, as women have done so much to afflict the modern supply of poultry, a woman should be the one to study out the remedies,” Dr. Pennington concluded.
“Perhaps a mere man, not endowed with woman’s native affinity for chickens, might have been able to conduce the cold-storage investigations successfully, in spite of the handicap of his sex,” The Oregon Daily Journal article continued. “But the fact is simply that mere man didn’t and that Dr. Pennington’s previous record marked her for the expert whom Secretary Wilson and Dr. Wiley wanted on the job.
“She took her degree as doctor of philosophy at the University of Pennsylvania, and has since carried on investigations in chemistry and bacteriology in connection with both public and private laboratories. The importance and the urgent public need of the government inquiry into the food supply of the people at large became so considerable that she relinquished all her other work to act as the food research expert under Dr. Wiley in the Department of Agriculture.
“The purpose of Dr. Pennington’s work was fundamentally, of course, about insuring the perfect food supply to the people at large. But the entire trade and all its allies realized the commercial advantages of the improved methods the government is seeking to discover and establish. Packers, cold-storage warehousemen, merchants, retailers, and far from least on the list, railroad companies – all have cooperated as heartily and helpfully as the most enthusiastic could desire.”
Mary conducted her experiments and testing of refrigerator boxcars, also referred to as reefers, from a special railcar connected behind the refrigerator boxcar. From her rolling laboratory, she tested food being transported under typical railroad conditions as well as monitored the car’s temperature and humidity. Her research revealed that the refrigerator boxcar’s insulation was too thin and that the method of construction allowed cracks to form in the exterior shell, leaving what little insulation there was exposed to the outside elements.
After weeks of analyses, Mary determined that the keys to superior refrigerator boxcars were insulated and the need for a forced air system to maximize air circulation in the car. “Correct insulation,” Dr. Pennington noted in an article from the August 17, 1930, edition of The Atlanta Constitution, “means walls made with several thicknesses of material between which is packed an insulator of recognized efficiency. This insulating material should completely surround the box, especially protecting joints, seams and corners. The outside of the box may be made of wood or metal, either of which should be both attractive and easily cleaned. The inside of the refrigerator requires a material which is impervious to the moisture and action of constant cleaning methods. A finish on the inside to absorb odors or hold moisture would develop improper sanitation and become a health menace. The hard, enameled, metal linings have proven extremely satisfactory. These should be made with as few seams as possible, so food cannot lodge in cracks and crevices. The necessary seams should be well protected.”
Using Mary’s research, railroad construction companies implemented the recommended changes. The creation of the modern refrigerator boxcar had a significant impact on the American economy. This technology eliminated the need to transport livestock, which required feed and hands to man the herd. With refrigerator cars, only the parts of the animal in demand needed to be shipped. Meat packing plants who could afford to build their own refrigerator cars to ship their product everywhere and icing services that provided the ice needed for the cars profited substantially. Consumers, too, reaped the reward from the reefers. More foods were made available and affordable to them.
Railroad lines anticipating the additional business ordered a fleet of refrigerator boxcars. According to the January 19, 1922, edition of The Salina Daily Union, the Union Pacific Railroad requested bids for 33,000 refrigerator boxcars.
Mary resigned her position at the Bureau of Chemistry’s Food Research Lab in 1922 and went to work for the American Balsa Company. While with the bureau, she had discovered that balsa wood was the perfect insulation to be used in refrigerator boxcars and wanted to explore other like areas where balsa could be of service. Mary explained to fellow chemists at a meeting in Scranton, Pennsylvania, in June 1921 that balsa was a tropical tree that weighed a little more than seven pounds per cubic foot as compared with the twenty-five-pound weight of a block of spruce of equal size. “It possesses wonderful heat resisting qualities and is extremely valuable in the construction of refrigerators of all types,” she told her peers.
Dr. Mary Pennington’s career in cold storage spanned more than thirty years and earned her the nickname “Ice Woman.” In addition to designing the modern refrigerator boxcar, she invented a process for scaling, skinning, quick-freezing, and dry-packing fish.
Dr. Pennington died on December 27, 1952, at the age of eighty.