Pasteurization

We use heat to keep food safe.

Heat kills tiny things in milk. This helps the food stay good longer. It stops us from getting sick.

This process is named after Louis Pasteur. He found a way to heat wine. This kept the wine from turning sour.

Today, we use it for milk and juice. It can be done in big machines. This makes our food safer to eat.

It is a very helpful way to eat.

Pasteurization is a way to keep food safe.

It uses mild heat to kill germs. These germs are called pathogens. They can make people very sick. This process also stops enzymes. Enzymes are parts of food that make it spoil.

This method is named after Louis Pasteur. He was a French scientist. In the 1860s, he found a way to heat wine. This kept the wine from turning sour.

Today, we use this for milk and juice. For milk, we use different ways to heat it. One way is called HTST. This means we heat milk to 72°C for 15 seconds. This keeps milk good for about two weeks in the fridge. Another way is called UHT. This uses very high heat for just 1 to 2 seconds. UHT milk can stay good for three months without a fridge!

Most liquid foods move through a machine. The food goes through a heating zone. Then it stays in a tube to get warm. Finally, it goes through a cooling zone. This makes our food safer to eat.

Pasteurization is a clever way to keep our food safe to eat.

This method uses mild heat to stop bad things from growing in food. These tiny living things are called pathogens, and they can make people very sick. The process also stops enzymes, which are parts of food that cause it to spoil. By using heat, we can make milk and juices last much longer. This helps prevent many dangerous diseases like tuberculosis and Salmonella. It is a very important tool for food safety around the world.

How does this heat treatment actually work?

For many liquids, the food moves through a continuous machine. First, it enters a heating zone to get warm. Next, it goes into a hold tube to stay at that temperature for a set time. For example, milk might be heated to 72°C for 15 seconds in a process called HTST. After that, it moves into a cooling zone to bring the temperature back down. This quick heating and cooling helps protect the taste and nutrition of the food. It also stops the food from changing color or flavor.

People have been trying to save food for a very long time.

In 1795, a chef named Nicolas Appert put food in glass jars and boiled them. He won a prize from the French military for this invention. Later, Peter Durand used tin cans to create modern canning. In the 1860s, a scientist named Louis Pasteur found a better way for wine. He discovered that heating young wine to about 55°C for a short time killed microbes. This kept the wine from turning sour without ruining its quality. We named the process pasteurization to honor his great work.

There are many different ways to use this heat today.

For milk, one method is called ultra-high-temperature or UHT. This heats milk at 135°C for only one or two seconds. When used with special packaging, this milk can last three months without a fridge. Most other liquids use a plate heat exchanger to stay safe. This machine uses thin stainless steel plates to move the food through heat zones. These machines help factories process huge amounts of milk and juice every day.

We can see the importance of this science in our own kitchens. Before milk was regulated, it could be very dangerous to drink. In England and Wales, 65,000 people died from tuberculosis in milk between 1912 and 1937. In the United States, the government began requiring pasteurization for milk sold between states in 1973. Today, most of the milk you buy at the store is much safer because of it. It is a way of using heat to protect our health. This makes sure that the food we love stays fresh and good.

Pasteurization is a specialized food preservation process. It uses mild heat to treat packaged foods like milk and fruit juices. This method aims to eliminate pathogens, which are harmful microorganisms that cause disease. It also deactivates enzymes that contribute to food spoilage. By destroying or deactivating these elements, pasteurization extends the shelf life of many liquid products.

The mechanism of pasteurization relies on precise temperature and time controls. In a continuous system, food typically moves through a heating zone. It then enters a hold tube to maintain the required temperature. Finally, it passes through a cooling zone to bring the temperature back down. This specific sequence helps prevent a phase change in the product. Cooling is also vital to stop the Maillard reaction and caramelization. These reactions can change the color and flavor of the food.

Different types of liquids require different heat parameters. The acidity of a food, measured by its pH, determines the treatment. Acidic foods have a pH of 4.6 or less. Examples include fruit juices and beer. In these foods, heat inactivates enzymes like pectin methylesterase and polygalacturonase. It also destroys spoilage microbes like yeast and lactobacillus. Less acidic foods have a pH greater than 4.6. Milk and liquid eggs fall into this category. For these, heat must destroy pathogens and spoilage organisms like molds and yeast.

There are several ways to apply this heat. High-temperature short-time (HTST) pasteurization is common for milk. This method heats milk to 72°C for 15 seconds. It provides a refrigerated shelf life of about two weeks. Ultra-high-temperature (UHT) pasteurization is even more intense. It heats milk at 135°C for only one to two seconds. When used with aseptic packaging, UHT milk can last three months without refrigeration. Some non-thermal methods also exist, such as pascalization or high-pressure processing (HPP). Another method is pulsed electric field (PEF) processing.

The history of food preservation is long and complex. Heating wine for preservation was known in China by AD 1117. It was also documented in Japanese diaries between 1478 and 1618. In 1768, Lazzaro Spallanzani proved thermal processing could make products sterile. He boiled meat broth for one hour and sealed it. In 1795, Nicolas Appert began experimenting with preserving food in glass jars. He won a 12,000-franc prize from the French military in 1810. Appert's method involved boiling jars in water to cook the contents.

Louis Pasteur revolutionized this field in the 1860s. During a summer holiday in Arbois, he studied why wine turned acidic. He discovered that heating young wine to 55°C for a short time killed microbes. This prevented souring without sacrificing the wine's quality. His work provided evidence for germ theory. Later, Peter Durand patented the use of tin cans in 1810. This led to modern canning. In the early 20th century, Milton Joseph Rosenau established milk standards. He suggested low-temperature heating at 63°C for 20 minutes.

Pasteurization has saved countless lives by making milk safer. Before regulation, raw milk was a major source of disease. Between 1912 and 1937, 65,000 people died of tuberculosis from milk in England and Wales. In the United States, the CDC reported that between 1998 and 2011, 79% of dairy-related outbreaks involved raw milk. This included 148 outbreaks and 2,384 illnesses. Pasteurization prevents diseases like tuberculosis, brucellosis, diphtheria, and scarlet fever. It also kills bacteria like Salmonella, Listeria, and E. coli O157:H7.

Modern food processing uses advanced equipment to manage these tasks. Many liquid foods move through plate heat exchangers. These consist of many thin, vertical stainless steel plates. They are ideal for low-viscosity products like nut milk or juices. For food in containers, producers use steam or hot water. If the packaging is glass, they use hot water to avoid thermal shock. This prevents the glass from cracking. This technology connects microbiology with industrial engineering to keep our global food supply safe.