Retorts are used for the sterilization and pasteurization of packaged products. These are two methods of heat treatment: sterilization is made at a temperature higher than 100°C, whereas pasteurization is made at a temperature lower than 100°C. Both methods preserve food, by eliminating pathogenic microorganisms.

How does a sterilization or pasteurization cycle proceed?
The stages of sterilization or pasteurization are built in three principal phases:
– The heating is the first phase of the cycle. It makes it possible to raise the autoclave until the target temperature of sterilization or pasteurization.
– The plateau is the following phase of maintain at the temperature of sterilization or pasteurization. It is the most important and the most critical phase of the thermal treatment, the respect of the couple time/temperature is obligatory.
– The cooling is the last phase of the process: it makes it possible to lower again the autoclave and the products in temperature.

What are the parameters to manage?
– Temperature: respecting the cooking recipe is essential to validate the heat treatment.
– Pressure: temperature variations involve pressure variations, especially inside the packaging. This can cause distortions. To avoid them, it is essential to control it, thanks to the counter-pressure.
– The duration : it is linked to the previous parameters and must be respected according to the validated conditions.

How to control the sterilization or pasteurization cycle ?
The evaluation of the heat treatment is done according to the sterilizing value (F0) or pasteurizing value (VP). It allows to measure the intensity of the technical treatment. It is calculated through the presence of a temperature probe placed at the heart of the product. The VS or VP allows to check the right progress of the thermal treatment and to determine the couple time/temperature of the cooking phase. This value depends of the type of product and the quantity of micro-organisms initially present.

How to avoid package distortion?
To prevent the package from blowing up or compressing during a cycle, the counter-pressure must be controlled and adjusted. When the package blows up, air must be added and the counter-pressure must be raised. Conversely, when the package is compressed, air must be released and the counter-pressure decreases. The counter-pressure can be controlled with the Packsensor, a system developed by Steritech, allowing the regulation of the counter-pressure depending of the deformation of the packaging.

What are the different types of autoclave ?
– Autoclave with Air/Steam process : the thermal treatment is done by injecting steam directly around the products. Cooling is done by spraying water on the products.
– Autoclave with water spraying process: the products are warmed by hot water sprayed on the products. Then they are cooled by the same process with cold water.
– Bi-process autoclave: it has the advantages of the two previous processes!
– Immersion autoclave: the products are submerged in hot water and then in cold water in order to achieve the complete cycle.

The type of autoclave is chosen according to your needs.

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