Pasteurization is a process named for and developed by French scientist Louis Pasteur that uses heat to kill many of the harmful bacteria and microorganisms found in some consumer goods (Staff, 2021).  Perishable items like juice, eggs and dairy products sold in grocery stores today are typically subjected to pasteurization as a way of both making them safer for consumption and extending their shelf lives.  One of the most widely recognized pasteurized products is milk.  While pasteurization itself was the result of deliberate development, the application of pasteurization to dairy products, was a happy accident borne out of an effort to drive down infant mortality in the US and has changed the course of history.

In 1863, Louis Pasteur received a letter from the court of Napoleon III that urged him to look into the spoilage of wine, a major French industry (Bramen, 2009).  By that time, Pasteur was already a well-known scientist whose germ theory would end up creating a new field of scientific study that would later become micro-biology.  His theories about bacteria and micro-organisms debunked many misconceptions at the time and paved the way for his groundbreaking work on fermentation.

Pasteur discovered that fermentation was a biological process, that the alcohol and carbon dioxide produced in bread and beer and wine was the result of micro-organisms, yeast, eating sugars in the base material.  Prior to this, many bakers and brewers believed that yeast had a tangential, supporting role, not a central one (Nelson, 2009).  It was this work in fermentation that laid the groundwork for his creation of the pasteurization process.  It also brought him the academic attention to make him the natural choice to solve the problem that led to the discovery of pasteurization. 

As previously mentioned, Pasteur was asked to solve the problem of wine spoilage.  Wine was a major industry in France and spoilage was a large source of loss for local vintners.   Drawing on techniques and insights gained from his work in fermentations, Pasteur observed that wine was not pure, there were many forms of bacteria and fungi present.  He knew from his prior work with yeast that these microorganisms could be causing or influencing the spoilage.  Finally, he knew that heating a substance for a short period of time could kill yeast so he reasoned it might work in this case too.  He had demonstrated this earlier when he heated beet wine in order to kill naturally occurring yeast so that vintners could introduce the desirable yeast that would create fermentation (Nelson, 2009). 

Pasteur began experimenting and found that heating the wine to a temperature between 140 and 212 degrees for a short period of time killed off many of the undesirable microorganisms in the wine.  And because the heat applied was relatively mild, it had little to no noticeable effect on the flavor of the wine once it cooled again.  Pasteur’s process of heating at relatively low temperatures in the absence of oxygen had the desired effect; the shelf life of wine was significantly extended. 

Pasteur never experimented with milk.  But in the early 1800’s, milk was a common transmission vector for pathogens like tuberculosis. In fact, infant mortality rates in the late 1800’s was 30-60 times higher than mortality rates today, due in large part to the misunderstanding of how germs and pathogens spread to infants (Currier & Widness, 2018).  Applying the process of pasteurization to milk, and subsequently to other food products, led to dramatic decreases in food borne illnesses and mortality.  Pasteurized food has been so effective at reducing the spread of pathogens that tuberculosis is no longer listed a food-borne pathogen by the FDA (White, 2010).   Indeed, in 1973 the US Food and Drug Administration mandated that all interstate sales of milk undergo the pasteurization process (Staff, 2021). 

While not exactly an accident, the work of one scientist to preserve the shelf life of wine led to saving millions of infants from food borne pathogens on a different continent.  This is especially notable because information did not travel as fast in 1880, or even in 1960, as it does today.  The work of a French scientist would not have been easy to find for scientists in the United States looking for answers to their infant mortality problem, especially since Pasteur worked with an entirely different substance.  Applying the pasteurization process to the infant mortality problem was innovative and the clear result of a series of happy accidents. 

If we take the definition of accident that indicates it is an event that happens by chance, then this certainly fits.  Pasteur began his work as a chemist and yet became involved in fermentation.  Pasteur was at the right point in history to have access to microscopes that were good enough to see what he needed to see.  Microscopes had been around since the early 1600’s but would not have been able to see the microorganisms that because Pasteur’s focus until improvements in structure and lens quality that happened in the 1800’s (Anderson, 2010).  Finally, Pasteur himself never worked on the US mortality problem.  He was charged with solving wine spoilage on a different continent.  That US scientists engaged in solving the problem knew of and thought to apply Pasteur’s work, all at a time preceding digital communication, is remarkable. 

 

 

References

Anderson, H. (2010). History of the Microscope. Retrieved from https://www.microscopemaster.com/history-of-the-microscope.html

Bramen, L. (2009). When Food Changed History: Louis Pasteur. Smithsonian. Retrieved from https://www.smithsonianmag.com/arts-culture/when-food-changed-history-louis-pasteur-58855064/

Currier, R. W., & Widness, J. A. (2018). A Brief History of Milk Hygiene and Its Impact on Infant Mortality from 1875 to 1925 and Implications for Today: A Review. J Food Prot, 81(10), 1713-1722. doi:10.4315/0362-028x.Jfp-18-186

Nelson, B. (2009). The Lingering Heat over Pasteurized Milk. Retrieved from https://www.sciencehistory.org/distillations/the-lingering-heat-over-pasteurized-milk

Staff, M. C. (2021). What Is Pasteurization? Learn About the History and Benefits of Pasteurization. Retrieved from https://www.masterclass.com/articles/what-is-pasteurization-learn-about-the-history-and-benefits-of-pasteurization

White, C. (2010). How Pasteurization Works. Retrieved from https://science.howstuffworks.com/life/cellular-microscopic/pasteurization1.htm