Home » Health » What is pasteurization? – EFE Health

What is pasteurization? – EFE Health

Even if we can’t see them, they are there. The pathogenic microorganisms they can contaminate food and make us sick. Currently, many of these diseases can be prevented thanks to the pasteurizationa process he developed Louis Pasteur in the decade of the 60s of the XIX century.

In those years, France had a major problem with wine, which threatened to ruin the exports of one of the country’s most prominent products.

Winemakers had difficulty guaranteeing the quality of the wine, which sometimes went bad without knowing why or how to remedy it.

Louis Pasteur, born on December 27, 1822, was then already a renowned scientist, so Napoleon III called him to find a solution.

How did pasteurization come about?

Luis Pasteur pasteurization
Luis Pasteur photographed by Eugène Pirou in 1884. Photo courtesy of the Institut Pasteur/Musée Pasteur

After a thorough study, Pasteur discovered that the wines decomposed due to the presence of microorganisms that intervened in the fermentation process.

To avoid this, he proposed heating the wine between 55°C and 60°C, a temperature that allows these microorganisms to be eliminated while preserving the aroma and flavor of the wine.

At first, this method did not quite convince the winemakers, until they found that the wine subjected to this process could be preserved in perfect condition for long periods of time.

Given the success with wine, beer makers also went to Pasteur to ask him for a similar solution that would allow this drink to be preserved. The scientist applied the same method to his country’s beer, at a time when, due to the Franco-Prussian War, the import of German beer had been restricted.

This method, today known throughout the world as pasteurization, in honor of its creator, has made it possible to preserve not only wine and beer, but many other foods, including milk.

“Milk and dairy products provide a wealth of nutritional benefits. However, raw milk, i.e. unpasteurized milk, can harbor dangerous microorganisms that can represent serious health risks”, points out the United States Food and Drug Administration (FDA).

Dangerous bacteria

“Raw milk can contain dangerous bacteria, such as Salmonella, E.coli, Listeria, Campylobacter and others that cause foodborne illnesses”, the organization emphasizes.


As explained by World Health Organization (WHO)people usually contract salmonellosis through the consumption of food of animal origin contaminated with Salmonella (mainly eggs, meat, poultry and milk).

Although there are also other foods that have been linked to transmission, for example, vegetables contaminated with manure.

Salmonellosis is a disease caused by bacteria Salmonella. It is characterized by the sudden onset of fever, abdominal pain, diarrhea, nausea and sometimes vomiting.

“In most cases, the symptoms of salmonellosis are relatively mild and patients recover without specific treatment. However, in some cases, particularly in young children and the elderly, the dehydration caused by the disease can be serious and life-threatening”, emphasizes the WHO.


Another bacteria that can cause food poisoning is the Escherichia coli. It is found in the intestines of people and animals, in the environment, and sometimes also in untreated food and water.

“Most types of E. coli are harmless and part of a healthy intestinal tract. However, some cause diseases that are sometimes serious such as diarrhea, urinary infections, respiratory diseases and bloodstream infections”, point out the specialists of the US Centers for Disease Control and Prevention (CDC).

To prevent them, from CDC they advise taking several precautions such as washing your hands well with running water and soap; cook the meat completely; do not drink untreated water and consume pasteurized milk and juices.

Wine pasteurization
Pasteur has a lot to do with the way wine is made today. EFE/ José Méndez


For its part, the Listeria can cause an infection called listeriosis. In general, this infection occurs through contact with food contaminated with the bacteria.

“The real problem of Listeria infection occurs in risk groups: immunocompromised patients, the elderly, pregnant women and infants. In immunocompromised or elderly patients, it is more common for the infection to spread to other organs and produce invasive listeriosis. In some cases, listeria affects the central nervous system and produces cases of meningitis or encephalitis that can be fatal,” he explains Andrés Sánchez Yagüe, specialist in gastroenterology.

“In pregnant women, the disease is usually not very symptomatic, but it can cause spontaneous abortion in one out of five cases. In addition, the infection can cross the placenta and cause fetal death or produce sequelae in the fetus. In other cases, premature birth can occur, with the risk of transmission to the fetus during childbirth”, adds Dr. Sánchez Yagüe.

The doctor recommends several measures to prevent listeriosis such as maintaining the hygiene of the surfaces on which food is handled; properly cook fresh meats and sausages and, if you belong to a risk group, avoid unpasteurized dairy products.


Food can also be contaminated by Campylobacter. According to the WHO, this bacterium “is one of the four main global causes of diarrheal disease and is considered the most frequent bacterial cause of gastroenteritis in the world”.

He also points out that in people with campylobacteriosis, complications such as bacteremia (presence of bacteria in the blood), hepatitis, pancreatitis and abortions have been observed with varying degrees of frequency. Post-infection complications include reactive arthritis (painful inflammation of the joints that can last several months) and neurological disorders such as Guillain-Barré syndromea form of paralysis similar to poliomyelitis”.

The WHO indicates that, generally, it is considered that “the main route of transmission is food, through meat and undercooked meat products, as well as unboiled or contaminated milk”.

Importance of pasteurization

To prevent these and other infections, the food industry uses pasteurization. The process consists of heating the food for a short period of time, as Louis Pasteur already did in the 19th century.

However, there are currently many types of pasteurization, which differ from each other by the temperature applied and the time during which the food is heated.

For example, the VAT pasteurization consists of heating the food to 63º C for thirty minutes; to the HTST pasteurization (High Temperature Short Time) the product is heated to 72º C for fifteen seconds and the UHT pasteurization (Ultra High Temperature) the food is subjected to temperatures of less than 138ºC for a few short seconds.

This last process, commonly used for milk that is bought packed in cartons, allows it to be kept in perfect condition for several months at room temperature as long as the container remains unopened.

Milk pasteurization
In UHT pasteurization (Ultra High Temperature) the food is subjected to temperatures of at least 130º C for a few seconds and is the one commonly used for milk that is bought packed in cartons, it allows it to be preserved in perfect condition for several months at room temperature as long as the package remains unopened. EFE/ Fernando Villar
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