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Appertization is a process that involves sterilizing perishable foods in airtight containers. It was developed in the 19th century by a French confectioner. The method ensures that products can be preserved for long periods of time. It can be used to preserve vegetables, meat, and cooked dishes. But what are the different stages of this process, which combines packaging and heat treatment?
Appertization of food, a preservation process using heat
Heat treatment of food is the most common process for long-term preservation of food products. Appertization is defined as a method of preserving food by heat sterilization in hermetically sealed containers. These containers can be glass jars, metal cans, trays, Doypack pouches, etc.
Food packaging and heat treatment: combining two techniques
The appertization process combines two techniques. First, food products are packaged in metal cans or glass jars. Then, it involves high-temperature heat treatment: sterilization. Placed in their packaging and exposed to water or steam at a temperature above 100°C, the food is rid of microorganisms, spores, and toxins that could make it unfit for consumption.
Once the bacteria have been destroyed or inactivated, food products can be stored at room temperature for several years. A minimum shelf life date (MSLD) always accompanies a product that has undergone appertization. Exceeding this date does not prevent the food from being sold or consumed. This date simply indicates the period during which the food retains its full taste and nutritional value.
How does it differ from pasteurization, another heat treatment?
Heat treatment techniques vary depending on the characteristics of the food product to be canned. If the food is acidic, such as fruit or vegetables in vinegar, for example, pasteurization will be used.
Unlike appertization, foods are subjected to moderate heat treatment. The temperature of the water or steam ranges between 70 and 100°C for a specified period of time. The foods are then rapidly cooled. Pasteurization destroys microorganisms in the same way as appertization. However, it does not kill their spores. This is why pasteurized non-acidic foods must be stored at low temperatures. Acidic foods (pH < 4.5) are stabilized by pasteurization and can be stored at room temperature.
Nicolas Appert, the French inventor of the technique of preserving food by appertization
The term “appertisation” comes from the surname of its inventor, Nicolas Appert (1749-1842). At the end of the 18th century, this French confectioner became interested in food, particularly in preserving food using heat. In 1810, he published a book entitled “The Art of Preservation.” Appert describes his technique in it. It earned him first prize in a government competition.
Appertization consisted of filling glass jars with the product to be preserved and sealing them tightly. The jars were then immersed in superheated water. The temperature and duration differed depending on the food. Finally, they were rapidly cooled. Nicolas Appert’s invention was taken up by the Englishmen Peter Durand, Bryan Donkin, and John Hall. They adapted it to metal cans, placing the containers in an autoclave for sterilization.
Canning, sterilization, cooling: the different stages of food preservation
Nowadays, various types of food can be canned using the Appertization process. This preservation method can be used for
Food canning and juicing
Appertization must take place very soon after the food is harvested. This is essential to preserve the freshness of the products. Once blanched or pre-cooked, the food is then canned. A covering liquid (juice or sauce) is added to the can. This liquid facilitates heat transfer during sterilization. Next comes sealing. The can is closed by removing as much air as possible. For glass jars, this process is called capping.
Sterilization with water or steam in an autoclave
An autoclave is a type of pressure cooker capable of withstanding the high pressure generated by the rise in water temperature. The product is heated using water or steam heated to a temperature above 100°C. Sterilization programs specific to the food, packaging, and autoclave used must be followed during the process. There are different types of autoclaves for packaged foods.
- Air-steam autoclave : uses a mixture of air and steam to preserve the packaging.
- Water spray autoclave: water is sprayed under pressure and can be recycled, thus saving on consumption.
- Bi-process autoclave: combining the two previous methods, this technology is suitable for large-capacity autoclaves.
- Immersion autoclave: the traditional autoclave that works by immersing containers.
Pressure cooling to stop heat treatment
The final stage in food canning: rapid cooling of the cans, directly in the pressure cooker. Low-temperature water is injected into the cooker, causing a thermal shock that stops the heat treatment. Once the canning process is complete, the cans undergo several quality checks before being stored or distributed.
Appertization is therefore the basis for the preservation qualities of canned food and other long-life food containers. Carried out in an autoclave, it allows the product to be heated and sterilized directly through its packaging using water or steam. Steritech specializes in autoclaves and continuous systems. We can guide you in choosing your appertization solution.
