Pasteurization and sterilization – what are the differences?

Since the dawn of time, mankind has been working to preserve food in a safe way. The aim has been to invent techniques for eliminating all bacteria and microorganisms that could be harmful to health. In this article, we will describe the two main examples: pasteurization and sterilization. 

Discover the differences between pasteurization and sterilization. 

What is the technical process of pasteurization?

French scientist Louis Pasteur invented the pasteurization process in the 19th century. Pasteurization was patented in 1865. The process involves raising the temperature of a product over a given period of time. 

There are two types of food pasteurization depending on the storage temperature

Our Steritech autoclaves can be used for two types of pasteurization. 

• Pasteurization of products with an acid pH below 4.5. Products can then be stored at room temperature.
• Pasteurization of products with a pH above 4.5. Products must be stored in a cool place.

The different objectives of pasteurization

Pasteurization heat treatment destroys pathogenic bacteria present in a product. However, pasteurization does not destroy certain spores or the most resistant strains of microorganisms. The destruction of bacteria and microorganisms depends on the pasteurization process. 

Certain pathogenic microorganisms have been destroyed in products with a pH below 4.5. No microorganisms can develop. The acidity of the product completes the preservation process. The same applies to products with a pH above 4.5, where certain pathogenic microorganisms have been destroyed. Cold completes the preservation process.

What is the shelf life of a pasteurized product? 

Once again, the shel life of pasteurized foods depends on the acidity of the product. 

• Products with a pH below 4.5: more than 12 months with DMD (date of minimum durability). The words “best before” must appear on the packaging.
• Products with a pH above 4.5: these are perishable foods. Shelf life is a few months. The words “best before” must appear on the packaging.

What is the technical process of sterilization?

Sterilization is a temperature-based food preservation process. Depending on sterilization protocols and your equipment, the heating temperature can reach at least 121°C under a pressure of 100 kPa. The duration of the process depends on the product.

What are the two types of food sterilization processes?

There are two types of low-temperature sterilization (UV, chemical or ionizing radiation, or filtration) specifically adapted to medical equipment. Only high-temperature heat treatments such as autoclaving can sterilize food products.

The different objectives of the sterilization process

The main goal of the sterilization process is to eliminate all microbes from a food preparation. Biological agents, such as spores and pathogenic organisms, are eliminated by raising the temperature for a given period.

What are the differences between pasteurization and sterilization processes?

The first difference between pasteurization and sterilization concerns their inventors. Nicolas Appert discovered the sterilization process, also known as appertization, at the end of the 17th century. Pasteurization was discovered by Louis Pasteur in the following century.

The differences in temperature

During the sterilization process, the temperature exceeds 100°C. All pathogenic organisms are destroyed, including spores. Canned food can be stored at room temperature. In the pasteurization process, on the other hand, the temperature remains below 100°C. Not all pathogenic organisms are destroyed, which is why food must be kept cold for non-acidic products. The use-by date must be respected. 

What is the shelf life for each process?

Sterilized products have a longer shelf life than the pasteurized products. This is because pasteurization does not destroy all pathogenic organisms. 

Which products are involved in each process?

The pasteurization process applies to all types of food: milk and its derivatives (butter, cream, etc.), fruit juices or beverages (wine, cider or beer), jams and even meat. All can be pasteurized. However, some foods, such as ready-made meals, must be kept refrigerated. 

Sterilization also covers a wider range of products : whole fruit, vegetables and ready meals. Steritech does not manufacture continuous pasteurizes for milk or fruit juices. In general, liquids such as milk and fruit juices can be pasteurized before bottling. 

Different times and temperatures for different processes

For both dry and moist heat sterilization, time and temperature vary according to the product concerned. The same applies to pasteurization, which depends on the product. However, rapid cooling must follow the process.

What is the right type of packaging for the product?

Sterilization and pasteurization processes are particularly well suited to different types of packaging. For example, a glass bottle can be used to sterilize vegetable soup. Flexible packaging such as plastic trays can also be used for sterilization and pasteurization. 

Why use pasteurization or sterilization?

We usually talk about the “technical” reasons for using pasteurization or sterilization. Let’s focus on other reasons to use these processes.

A gain in food sovereignty 

At Steritech, we’re committed to the concept of food safety. Crop variability due to climatic phenomena (heatwaves, drought, frost) has become the norm. Thanks to sterilization, food can be stored for several years at room temperature.

Environmentally-friendly cooking and food preservation

Our autoclaves are “2 in 1” solutions. Cooking can be carried out at the same time as heat treatment. This type of preservation requires no energy consumption. We have always been committed to sustainable development. Our pasteurization and sterilization solutions save energy.

Make the right choice and opt for a company renowned for its expertise in sterilization and pasteurization. Discover our range of autoclaves, the fastest on the market. Do you have any further questions? Please do not hesitate to contact us.