In order for the production of canned food – vegetables or animals – to be carried out under good safety conditions and for these to be preserved at room temperature, they must be sterilized. Additionally, in most regulatory bodies of all countries, food sterilization through autoclaves is a legal requirement for producing and marketing canned goods.
Food sterilization
The sterilization of canned food, also known as commercial sterilization, is a physical technique for preserving food sealed in a container and subjected to high temperatures for a period of time to completely destroy its microorganisms, whether pathogenic or not, and spores.
We refer to it as a physical method because it does not involve gases or chemicals (chemical sterilization).
Thanks to the complete eradication of any bacteria or fungi, the shelf life of sterilized products is significantly extended, often exceeding four months, and they do not require refrigeration for preservation.
Unlike pasteurization, sterilization eliminates all types of microorganisms and spores. Pasteurization only eliminates most microorganisms and does not remove spores. There is confusion between the two techniques when it comes to microorganisms or temperature. For more information, we recommend reading our post What is the difference between sterilization and pasteurization?
Sterilization without altering the product
However, the use of high temperatures in sterilization can affect the quality of the product by reducing its nutritional value, as it destroys some vitamins and aromas. It can also cause some organoleptic changes, such as alterations in color and flavor.
In order to minimize these potential losses as much as possible, it is essential to correctly balance the parameters of exposure time and temperature. And for that, the following must be taken into account:
Characteristics of the food
Although all the characteristics of an ingredient—shape, length, width, and composition—are important when sterilizing, the level of acidity, the pH, is the most crucial element, as it determines the viability of the product.
The vast majority of foods fall within a pH scale of 3 to 7. The more acidic a food is, the lower its pH value.
Foods with a neutral pH (>4.5) are usually sterilized at temperatures above 100ºC, because in products with an acidic pH, microorganisms cannot grow or are more sensitive to thermal treatment, and therefore lower temperatures (below 100ºC) are used.
The type of packaging
The container also plays an important role when it comes to food preservation. The material it is made from, its porosity, shape, and the morphology of the sealing are key to ensuring the quality and shelf life of the product, preventing possible oxidation. You can find more information about the different types of packaging suitable for sterilization on our Blog.
All types of meats, fish, vegetables, and fruits are typically sterilized. This also includes jams, syrups, pickles, creams, soups, sauces, and stews, among others.
The most commonly used method in the sterilization of canned food is wet heat, which uses steam from water to transfer thermal energy and eliminate microorganisms. This is a system with a short cycle due to the high heat transfer capacity of water vapor.
The sterilization process
The sterilization of a food item using an autoclave is structured in three phases:
Heating phase
Sterilization phase:
Cooling phase:
Origins of food sterilization
The sterilization of canned food originated from the technique of heat preservation, also known as ‘appertization’. This was discovered in 1810 by Nicolas Appert, a French confectioner and cook, who founded the world’s first commercial canned food factory.
He developed this process at the request of the French army, which urgently needed food to be preserved for a long period of time. Based on this premise, Appert came up with the idea of placing food in glass bottles sealed with cork stoppers held with wire and sealed with wax or lacquer, and then boiling them in water for a long period of time.
TERRA Food-Tech® Autoclaves for sterilizing canned packaged food
With TERRA Food-Tech® compact autoclaves for canned packaged food, determining the precise temperature and time for cooking and sterilizing any type of food is much easier, as the temperature probe, which regulates the entire process, is placed in a product sample. This allows for perfect process control, preserving organoleptic properties, minimizing potential changes in the nutritional characteristics of the packaged product, and complying with all food industry requirements and standards.
Also, remember that at TERRA Food-Tech® we offer free consulting and technical support for the production of your canned goods during the first 3 months when purchasing an autoclave. For more information, feel free to contact our sales team, we will be happy to assist you.
