In simple terms, a sterilizer is a closed, pressurized heater used to heat food sealed in a container. For foods that are packaged in containers that require commercial aseptic sterilization, a variety of different sterilizer systems can be used.

The sterilizer system has some of the same characteristics: The system is pressurized and the transfer temperature is much higher than boiling water. The system uses a medium, called a heating medium or a sterilizing medium, as a means of transferring heat to the product. The media used in the pot include pure steam, hot water (the container is fully immersed in water, water spray or water spray) and steam / air mixture.

Some systems use overpressure during sterilization and cooling to maintain the integrity and balance of the container to offset the pressure inside the tank. This is necessary because some packaging containers have limited tolerance to internal pressure. Some examples of overpressure sterilization containers are also semi-rigid plastic containers with heat-sealed or bi-metal seam can ends, soft bags, metal trays, cardboard containers and glass jars. The pressure at 250 ° F is about 15 psig (pounds per square inch), and any pressure exceeding 15 psig applied to the retort is called overpressure. Provide overpressure, such as 25-35psig sterilization system can operate at higher temperatures.

The operation of the sterilizer must be appropriate to ensure that the container is commercially sterile after sterilization.