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

History of low temperature pasteurization

During the Middle Ages, people used heat to extend the shelf life of food, such as wine and beer, by heating them to prevent souring. In 1864, Louis Pasteur developed the process of pasteurization with the specific goal of prolonging the lifespan of his favorite wine.

Despite Pasteur's experiments with wine, pasteurization faced significant resistance and took many years to gain widespread acceptance due to widespread skepticism.

Even though Pasteur proposed pasteurization for wine in 1868, it was not embraced by fine winemakers who traditionally preserved their wines through meticulous cellar maintenance and strict manufacturing methods. They found that pasteurized wine acquired an undesirable "cooked" taste.

In 1882, the first commercial milk pasteurizers were introduced, utilizing a high-temperature, short-time (HTST) process.

In 1879, Franz von Soxhlet invented the Soxhlet extractor, and in 1886, he advocated for the application of pasteurization to milk and other beverages.

Upon realizing that a low-temperature, long-time heating process (referred to as batch pasteurization) could effectively eliminate the TB bacterium in milk, governments promoted the adoption of this method.

By 1912, Milton Rosenau, an American public health official at the United States Marine Hospital Service, set standards for low-temperature pasteurization: slow heating at 60°C (140°F) for 20 minutes, as outlined in his publication "The Milk Question" (1912).

Low-temperature pasteurization successfully preserves the delightful, fresh flavor of milk. In this process, milk is gradually heated in a temperature-controlled vat.

In response to health concerns, U.S. states started enacting dairy pasteurization laws, with the initial legislation passed in 1947, and in 1973, the U.S. federal government made pasteurization mandatory for milk used in interstate trade.
History of low temperature pasteurization

Soxhlet apparatus

Milk heat treatment – pasteurization in history

Pasteurization, the name is derived from that of Louis Pasteur, whose discoveries in the 1860s and 1870s demonstrated that heating liquids, especially wines, to fairly low temperatures, such as 60°C, improved the keeping quality during storage.

In the middle of nineteenth century, commercial winemaker approached Louis Pasteur to seek a solution of abnormal fermentation and subsequent spoilage of wines and beers. Pasteur studied the problem during 1864–65 and found that some microorganisms are the root cause of abnormal fermentation leading to early spoilage of wines and it can be prevented by heating the wine around 60°C, which kills these microorganisms.

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. This method was successful in reducing infant morbidity and mortality rates.

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.

In 1867 Pasteur applies heat to milk and reports the process postponed milk souring.

The first application of pasteurizing heat treatments to milk may have been performed by Franz von Soxhlet in 1886, who pasteurized bottled milk fed to infants.

The first commercial pasteurizer was introduced in Germany in 1882, but it was not until 1893 that a commercial unit was established in the U.S. for pasteurization of raw milk.

Gerber and Wieske pasteurized milk in bottles at 65°C for 1 h as early as 1888. The first commercial pasteurizer was made in Germany in 1882; pasteurization on a commercial scale quickly became common practice in Denmark and Sweden in the mid-1880s.

In Denmark and Sweden, commercial pasteurization of milk was common as early as the mid-1880s, due in part to the early recognition by Danish butter makers of its merits. However, cities in the United States were much slower to openly embrace pasteurization techniques.

In the early 1900s, in Arizona, Jane H. Rider "publicized the link between infant mortality and contaminated milk, and finally convinced the dairy industry to pasteurize milk."

The first pasteurized milk ordinance was published in 1924 in the November issue of Public Health Reports; pasteurization was defined as a heating process of not less than 142°F (61.1°C) for 30 min in approved equipment.

In 1956 minimum temperature for vat pasteurization was raised from 142°F of to 145°F of based on heat resistance of Coxiella burnetii. Based on University of California Davis studies in late 1940's 1966 FDA memorandum accepts dual stem (CIP) flow diversion device to be used in HTST systems.

Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.

Milk heat treatment – pasteurization in history 

Pasteurization of milk in bottles

The custom of preserving milk by heat may be 'as old as the cow and the use of fire'. Pasteurization, named after French scientist Louis Pasteur, was introduced in milk in the late 1800s. The first application of pasteurizing heat treatments to milk may have been performed by Soxhlet, who pasteurized bottled milk fed to infants.

In 1880, British milk bottles were first produced by the Express Dairy Company. Gerber and Wieske pasteurized milk in bottles at 65°C for 1 h as early as 1888. Pasteurization in bottles has been practiced in certain localities for a considerable period of time. Pasteurization in bottles by the process of Gerber, which consists of heating milk in bottles for one hour at 65° C. (149° F.) during which they are agitated, had been practiced in their dairies for 15 years previous to 1903.

By 1898, pasteurization of all bottled milk was made compulsory in Denmark. The process of pasteurizing in bottles consists in bottling the milk in specialty constructed bottles of sufficient size to allow a space in the top of the bottle to take care of the expansion of the milk during heating.

After the milk in the bottles has reached the pasteurizing temperatures, the temperature is maintained for 30 minutes; the hot water is then replaced by cold and the milk cooled.

The first commercial pasteurizer was made in Germany in 1882, using a high-temperature, short-time (HTST) process; pasteurization on a commercial scale quickly became common practice in Denmark and Sweden in the mid-1880s. In 1894 – Anthony Hailwood from England developed the milk pasteurization process to create sterilized milk, and became the first person to sell sterilized milk in the United Kingdom.

What is believed to be the first commercially-operated milk pasteurizer in the United States of America (USA) was installed in Bloomville, New York in 1893.
Pasteurization of milk in bottles

Milk heat treatment

The term pasteurization has been coined after the name of Louis Pasteur of France, who in 1860-64 demonstrated that heating wine at a temperature between 122 to 140 ° F killed the spoilage organisms and helped in its preservation.

Although Louis Pasteur pioneered studies on heat treatment for preservation of the wine, pasteurization of milk first was attributed to Dr Frans von Soxhlet of Germany in 1886. He the first person to suggest that milk sold to the public to be heat treated.

Dr Frans von Soxhlet, an agricultural chemist also invented the Soxhlet extractor in 1879 and in 1886 he proposed he proposed that pasteurization be applied to milk in order to prevent disease and spoilage.

The son of a Belgian immigrant, Soxhlet is also known as the first scientist who fractionated the milk proteins in casein, albumin, globulin and lactoprotein. Furthermore, he described for the first time the sugar present in milk, lactose.

Frans von Soxhlet completed his PhD in Leipzig in 1872 before became an assistant at Landwirtschaftliches und tierphysiologisches Institut in Leipzig.
Milk heat treatment

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

Ohmic heating

Both irradiation and microwave heating employ radiant energies which affect foods when their energy is absorbed whereas ohmic heating raises the temperature of foods by passing an electrical current through the food.

Ohmic heating is one of the newest methods of heating foods. Ohmic heating’s major advantage is that is simultaneously heats solid pieces and liquids in a food with minimal destruction. It has been shown that Ohmic heaters can provide an interesting alternative to heat exchanger for thermal processing applications.

Georg Simon Ohm (1789-1854)

In 1827, German physicist, Georg Ohm published his treatise: Dei galvanische Kette, mathematisch bearbeite where he described what is today known as Ohm’s law.

But recognition of the thermal effects of electricity within a conductor was first elucidated by James Prescott Joule in 1840.

This resulted in a number of patents on the heating of flowable materials in the latter part of the nineteenth century. The ‘electric pasteurization’ process was used for milk treatment in six states in the United States in the 1930s.

In the 1980s, Ohmic heating was introduced by APV, who licensed the technology from the Electricity Council of Great Britain.

During this time the technology has achieved some industrial applications that include pasteurization of liquid eggs and processing of fruit products. Ohmic heating has shown good potential for blanching, evaporation, dehydration, fermentation, extraction, sterilization and pasteurization of food products.
Ohmic heating

Pasteurization in United States

Pasteurization is a technique of heating to reduce spoilage. It was developed initially by Louis Pasteur originally for wine and then applied to milk.

Pasteurization began in the United States as early as 1893, when private charity milk stations in New York City began to provide pasteurized milk to poor children through the city health department, a movement that spread to other cities.

In 1914, the discovery of tuberculosis in cows in a certified milk farm proved that pasteurization was the only way to produce safe milk. As early as 1908, Chicago was the first major US city to require pasteurization of milk.

In 1914, New York and Philadelphia required pasteurization of milk. In 1917, most major US cities required that all milk be pasteurized.

By the 1920s, pasteurized milk was commonly available throughout the United States and Canada and was considered compulsory in most large city.

By the second decade of this century, the United States was pioneering in commercial pasteurization as its method of guaranteeing a clean infant food supply.
Pasteurization in United States

History of Pasteurization

History of Pasteurization
Pasteurization is named for the French scientist Louis Pasture (1822-1895). In 1856, 34 year old Louis Pasteur began his fourth year as the Head of Sciences at the University of Lille in France.

In the fall of the same year, Maurice D’Argineau, a local businessman, found Pasteur in his cramped corner lab.

D’Argineau’s consistent failure to make wine from his fields of sugar beets without it going sour was driving him to financial ruin. Pasteur was particular intrigued by the problem since it hinted at the involvement of one of his pet interests and he readily agreed to study the matter.

Although he first experimented with this process in 1862, pasteurization was not put to use until the early twenty century.

In the United States pasteurization was championed by Alice Catherine Evans (1881-1975), a microbiologists who worked for the US department of Agriculture.

Evans suffered from a disease known as brucellosis (undulant fever) and in 1918 she discovered that brucella, the bacterium that caused her disease, could be found in cow’s milk.

Scientists eventually determined that brucella was not the only milk borne bacterium. Milk can harbor other bacteria – such as E. coli, salmonella, and listeria – which can cause harmful and even life threatening infectious in the young, the old, pregnant women and the infirm.

Indeed, unpasteurized cow’s milk was a very common cause of tuberculosis, typhoid fever and salmonellosis.

Evans advocated on behalf of pasteurization for years after her discovery. Finally in the 1930s, milk pasteurization became mandatory under US law.
History of Pasteurization