Pasteurization: Safeguarding Public Health and Food Safety

Pasteurization, a process named after the renowned French scientist Louis Pasteur (1822-1895), revolutionized food safety and preservation. In 1856, a 34-year-old Pasteur, then the Head of Sciences at the University of Lille in France, was approached by Maurice D’Argineau, a local businessman facing financial ruin. D’Argineau's repeated failures to produce non-sour wine from his sugar beets piqued Pasteur's curiosity, as it aligned with his research interests in fermentation and microorganisms. Pasteur readily agreed to investigate the matter, laying the groundwork for what would later become pasteurization.

Pasteur's initial experiments in 1862 involved heating wine to a specific temperature to kill harmful microbes without affecting the wine's taste. This breakthrough, however, did not see widespread application until the early 20th century, as the scientific community and industries gradually recognized its significance.

In the United States, pasteurization gained traction thanks to the efforts of Alice Catherine Evans (1881-1975), a pioneering microbiologist with the U.S. Department of Agriculture. Evans contracted brucellosis (undulant fever) in 1918 and discovered that Brucella, the bacterium responsible for her illness, was present in cow's milk. Her research revealed that milk could harbor a range of dangerous bacteria, including E. coli, Salmonella, and Listeria, which posed serious health risks, especially to vulnerable populations such as the young, elderly, pregnant women, and the infirm.

Before pasteurization became common practice, unpasteurized milk was a significant cause of diseases like tuberculosis, typhoid fever, and salmonellosis. Despite facing skepticism, Evans tirelessly advocated for milk pasteurization, emphasizing its importance in preventing these life-threatening infections. Her efforts, alongside mounting scientific evidence, eventually led to mandatory milk pasteurization in the United States by the 1930s.

Today, pasteurization remains a cornerstone of public health, ensuring that milk and other dairy products are safe for consumption, significantly reducing the incidence of milk-borne diseases, and saving countless lives worldwide. The legacy of Louis Pasteur and Alice Catherine Evans continues to impact global food safety standards.
Pasteurization: Safeguarding Public Health and Food Safety

Invention of pasteurization process by Louis Pasteur

Louis Pasteur earned his bachelor of arts degree (1840) and bachelor of science degree (1842) at the Royal College of Besançon and a doctorate (1847) from the École Normale in Paris. In 1854 Pasteur was appointed professor of chemistry and dean of the science faculty at the University of Lille. There, he worked on finding solutions to the problems with the manufacture of alcoholic drinks.

In 1857 Pasteur left Lille and returned to Paris, having been appointed manager and director of scientific studies at the École Normale Supérieure. That same year he presented experimental evidence for the participation of living organisms in all fermentative processes and showed that a specific organism was associated with each particular fermentation. This evidence gave rise to the germ theory of fermentation.

In 1863, at the request of the emperor of France, Napoleon III, Pasteur studied wine contamination and showed it to be caused by microbes. In 1864 Pasteur discovered that heating beer and wine was enough to kill most of the bacteria that caused spoilage, preventing these beverages from turning sour. The process achieves this by eliminating pathogenic microbes and lowering microbial numbers to prolong the quality of the beverage.

He then invented a process where bacteria could be removed by heating the wine to 50–60 °C (120–140 °F) then cooling liquid, a process now known universally as pasteurization. He completed the first test on April 20, 1862. Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.

The custom of preserving milk by heat may be ‘as old as the cow and the use of fire'. William Dewes recommended heating milk in the home before feeding to infants some 40 years before Pasteur conducted his experiments. Dewes observed that if the milk was heated to boiling point and cooled quickly, the tendency to spoil was reduced. Also preceding Pasteur was the contribution of Gail Borden who, in 1853, patented a process for heating and condensing milk under vacuum followed by addition of sugar for preservation.

Pasteurization was named after Louis Pasteur, who applied heat treatment to improve the shelf life of wine. Later, the process was applied to milk. Originally, the temperature–time combination for pasteurization was based on the amount of heat treatment required to destroy Mycobacterium tuberculosis var. bovis, which caused tuberculosis and was considered to be the most heat-resistant pathogen in milk at the time. Currently, the temperature–time setting is based on thermal death time studies for the most heat-resistant pathogen found in milk, Coxiella burnetii, which causes Q fever.

Invention of pasteurization process by Louis Pasteur