Lloyd Augustus Hall

American chemist and inventor Lloyd Hall (1894-1971) created an innovative method of preserving meat known as “flash-drying.” He also worked to find methods to combat spoilage and rancidity in various food products such as spices and oils; in all, he published more than 50 scientific papers and received about 105 patents. An active supporter of scientific and civic causes, in 1955 Hall became the first African American to sit on the board of directors of the American Institute of Chemists.

Discovered Interest in Chemistry

Lloyd Augustus Hall was born on June 20, 1894, to Augustus and Isabel Hall in Elgin, Illinois, about 40 miles northwest of Chicago. Augustus Hall was a high school graduate and a Baptist minister; his own father had come to Chicago in the 1830s and had become the first pastor of the Quinn Chapel African Methodist Episcopal Church, the city's first African-American congregation, in the 1840s. Isabel Hall was also a high school graduate— uncommon for women, especially African-American women, in the late 1800s. Her mother had escaped slavery on the Underground Railroad as a teenager and settled in Illinois.

The Hall family moved to nearby Aurora, Illinois, when Lloyd Hall was a child. He attended East Side High School in Aurora, and there became interested in chemistry. He was also active in activities such as debate, track, football, and baseball. During his high school years, Hall was one of only five African-American students at the school. In 1912 he graduated as one of the top ten students in his class and received scholarship offers from four Illinois universities. Hall entered Northwestern University in nearby Chicago. There he studied chemistry while working his way through school. He graduated with a bachelor of science degree in 1916 and began pursuing graduate studies at the University of Chicago.

Early Career

Despite Hall's academic qualifications, racism affected his employment prospects; for example, he was hired for a job sight unseen with the Western Electric Company, but turned away when he arrived for work in person. Many other companies unwilling to employ an African-American chemist also rejected Hall, before he found a job with the Chicago Department of Health Laboratories in 1916. There, Hall quickly was promoted to senior chemist. During World War I, Hall served as assistant chief inspector of powder and high explosives in the Ordnance Department of the U.S. Army, primarily inspecting the output of a Wisconsin explosives plant. After the war ended in 1919, Hall was offered a position as chief chemist with the Ottumwa, Iowa-based meatpacking firm John Morrell & Company. On September 23 of that same year, Hall married Myrrhene E. Newsome, a schoolteacher from Macomb, Illinois. The couple later had two children, Kenneth and Dorothy.

Hall worked at John Morrell & Company until 1921, when he returned to Chicago to take the position of chief chemist with the Boyer Chemical Laboratory. He worked there only briefly before becoming president and chemical director of a consulting laboratory, Chemical Products Corporation.

During these early years of his career, Hall developed an interest in food-related chemistry, and this area of expertise would ultimately make his name as a chemist. In the early 1920s, many companies sought ways to cheaply and safely preserve food. One of Hall's clients was Griffith Laboratories, run by a former Northwestern classmate and lab partner of Hall's, Carroll L. Griffith. In 1924 Griffith Laboratories offered Hall laboratory space where he could conduct research while maintaining his consulting business. The following year, Hall became Griffith Laboratories' chief chemist, director of research, and, according to his biography on the Griffith Laboratories Web site, its “first technical mastermind.” In 1929 Hall gave up his consulting business. He remained with Griffith until his retirement in 1959.

Created Flash-Drying Technique

At Griffith Laboratories, Hall turned his interest in food chemistry specifically to the science of meat curing. Curing techniques intended to preserve and enhance the flavor and appearance of meat had been used for some time; table salt mixed with chemicals such as sodium or potassium nitrate was a well-known curing compound. Hall sought to improve upon this method by combining sodium nitrite, sodium nitrate (saltpeter), and sodium chloride (table salt). However, a significant problem arose: because the sodium nitrite and sodium nitrate affected the meat considerably more quickly than did the sodium chloride, the meat fell apart before it was preserved. Hall considered possible methods to delay the effects of the sodium nitrite and sodium nitrate, so that the sodium chloride would have sufficient time to fully preserve the meat.

Hall's solution to this challenge revolutionized the meat-curing industry. He determined that by including small amounts of sodium nitrite and sodium nitrate within crystals of sodium chloride, the quicker-acting chemicals would not reach the meat until after the slower-acting sodium chlorite had dissolved. This meant that the meat was fully preserved before it was exposed to the curative properties of the sodium nitrite and sodium nitrate. In order to encapsulate the chemicals within the sodium chloride crystals, Hall developed a “flash-drying” technique. First, he made a strong mixture of sodium chloride containing small amounts of sodium nitrite and sodium nitrate. He then quickly evaporated the mixture over heated metal rollers, leaving only the flash-dried crystals. These crystals looked like salt, but had the capability to quickly and safely preserve meat, locking in its freshness.

Despite this great success, Hall's work was not complete. He discovered that the flash-dried crystals tended to absorb moisture from the air when stored, rendering them less effective. To solve this problem, Hall sought a way to deter the absorption of moisture by the crystals. He struck upon the idea of adding a combination of glycerin and alkali metal tartrate to the prepared flash-dried crystals. This changed their consistency from a salt-like one to a powdery one, and increased their ability to effectively preserve the meat. Finally, Hall determined that using chemically softened water in the flash-drying process improved its efficacy.

Experimented in Food Chemistry

After finalizing the flash-drying process, Hall turned his attention to other areas of food chemistry. At the time, food packers pre-seasoned their meats with such various spices as garlic powder and paprika before shipment, thinking that this pre-seasoning would improve the preservation of the meat during transport. However, this seasoned meat usually deteriorated more, rather than less, quickly. Hall found that the spices used in the seasoning process contained bacteria that hastened the spoilage of the meat, and began seeking a way to, as Louis Haber wrote in Black Pioneers and Science and Invention, “effectively sterilize these foodstuffs and at the same time preserve their appearance, quality, and flavor with no noticeable change.”

Hall researched this problem for some time. Finally, he discovered that by using the gas ethylene oxide, he could kill germs in food. Because naturally-occurring moisture and gases in the meat prevented the ethylene oxide from fully reaching every surface, Hall first introduced the meat into a vacuum. This removed all barriers to the ethylene oxide, which he then used to sterilize the various foodstuffs. This discovery led to the invention of food products that contained not only spices, but also proteins, baking ingredients, and others. James Michael Brodie observed in Created Equal: The Lives and Ideas of Black American Innovators that this method “still is utilized throughout the world by hospitals for such items as bandages, dressing, drugs, sutures, and cosmetics,” showing its lasting effects on chemical products.

Hall soon returned to the question of food preservation by working with fats and oils. These spoiled quickly, often due to contact with oxygen. Hall began experimenting with different antioxidants to prevent this contact. Eventually, he isolated some chemicals that were effective as antioxidants, but was faced with a new challenge: these often did not dissolve in fats such as those Hall hoped they would preserve. To solve this problem, Hall contained the antioxidants in chemicals that did dissolve in fats. This process greatly increased the amount of time refined fats and oils could be safely stored without turning rancid. Eventually, he replaced some of the original materials used, creating an antioxidant salt mixture.

Hall made other important chemical discoveries during his years at Griffith Laboratories. He worked with proteins, finding a way to break them down to extract their flavoring materials. An entry on Hall in Contemporary Black Biography commented that this was “among Hall's most successful and most widely used products …. [It] convinced Griffith Laboratories to open a large manufacturing facility devoted to protein hydrolysates.” During World War II, Hall again worked the U.S military, this time serving on a food research committee for the scientific advisory board of the Quartermaster Corps of the Army. Haber maintained that Hall was “invaluable in solving problems of maintaining military food supplies in pure and palatable form.”

One of Hall's last great food discoveries occurred in 1951. He improved the process for curing bacon from one that took up to two weeks to one that took only hours. Like Hall's other food discoveries, this process also enhanced the appearance and safety of the cured meat.

Retirement and Legacy

In 1959 Hall retired from Griffith Laboratories. That same year he received an honorary membership award from the American Institute of Chemists, honoring his leadership in food chemistry. After retirement, Hall and his wife relocated to Pasadena, California, where he resided for the rest of his life.

Haber noted that “Hall does not separate the chemist from the citizen.” Hall's dedication to civic affairs lasted throughout his life. In the 1930s, as a supporter of civil rights, Hall first served on the Chicago Executive Committee of the National Association for the Advancement of Colored People (NAACP) and later on the Board of Directors of the Chicago Urban League. He served on the Illinois State Food Commission and consulted with the George Washington Carver Foundation in the 1940s, and worked with the Institute of Food Technologists, serving on the organization's board in the early 1950s. During the late 1950s, Hall was active in the Hyde Park-Kenwood Conservation Community Council, an organization that worked for urban renewal in Chicago. From 1959 to 1960, Hall served as a member of the Board of Trustees of the Chicago Planetarium Society, acting as a science and education adviser to the Adler Planetarium.

After his official retirement in 1960, Hall continued his scientific and educational pursuits. Shortly after his retirement he traveled to Indonesia to serve as a consultant to the United Nations' Food and Agricultural Organization. In 1962 President John F. Kennedy appointed Hall to the American Food for Peace Council, which oversaw the donation of food to developing nations. Hall remained in this position until 1964. He was also active in organizations such as the American Red Cross, and worked on the SEED project, which aimed to educate underprivileged youth who were interested in chemistry careers.

Hall died on January 2, 1971, in Altadena, California. By the time of his death he had received 105 patents, covering areas such as solid seasonings, flavoring compounds, and protective food coatings. He had also received honorary doctorates from Virginia State University, Howard University, and the Tuskegee Institute. In 2004 Hall was posthumously inducted into the Inventors' Hall of Fame in honor of his pioneering contributions to the field of food preservation and science.