First of all, we need to know that the different packaging materials will determine the structure of the sterilization retort machine chosen.In order to obtain a better heating environment for different packaging materials, there are sterilizing kettles with different heating forms and structures (steam type, water spray type, water bath type, steam air type), etc.;
The difference of contents in packaging materials will determine the formulation of the sterilization process (heating, heat preservation, cooling, and pressure changes corresponding to each sterilization stage) and the structure of the sterilization retort machines (stationary, rotating, shaking) to adapt to the state of handling the sterilized materials during the sterilization process. Let’s discuss the different sterilization retort structures corresponding to various packaging materials.
Flexible packaging products: The shape of flexible packaging products can fluctuate with the shape of the product. If the flexible packaging is evacuated, the shape of the packaging material will be close to the outer surface of the product, showing the appearance of the material. Because it is a vacuum-packed product, the pressure in the sterilization retort during the sterilization process can be at a certain value higher than the vaporization pressure at the sterilization temperature of the circulating water. Under such prerequisites, the constant pressure sterilization mode is a more suitable choice. As for the heat transfer effect, the product is fully immersed in water quickly and fully. That is, for soft packaging vacuum products, the sterilization mode is a water bath or water immersion sterilization retort machines.
Glass bottle packaging products: During the sterilization process of glass bottles, attention should be paid to the ambient temperature not to change suddenly. Glass bottles are rigid materials and are usually filled at high temperatures, so that the pressure in the packaging material of glass bottle products at normal temperature is lower than atmospheric pressure. That is to say, it is in a negative pressure state (one purpose of the negative pressure state is to prevent the bottle cap from being dented once the activity of spoilage bacteria in the material in the bottle produces some gas and causes the pressure in the bottle to rise during the storage and transportation process before consumption. raised to remind consumers that the contents of the bottle are no longer edible). However, during the high-temperature sterilization process, the pressure inside the glass bottle will increase. In order to prevent the circulating water outside the bottle from entering the bottle through the seal of the bottle cap, the pressure outside the bottle should not be higher than the pressure inside the bottle. According to these characteristics, for glass bottle packaging products, it is more appropriate to choose the top spray sterilization mode.
Packaging materials such as iron cans appear to be iron cans, but due to their relatively large specifications and sizes, their ability to withstand pressure differences is relatively weak. Therefore, during the sterilization process, the pressure in the sterilization retorts needs to be strictly controlled. Adjust as the temperature changes so that the pressure difference experienced by the iron can can be controlled within a tolerable range. One thing to note is that for the same temperature, the corresponding pressures are different during the heating stage and the cooling stage. Because the heating stage transfers heat to the inside of the product, and the temperature in the tank is lower than the temperature in the sterilizing retorts, the pressure required in the sterilizing retorts will be lower; while in the cooling stage, the heat inside the product is dissipated outward, and the tank If the temperature in the body is higher than the temperature in the sterilization kettle, the pressure required in the sterilization retorts will be higher, which needs to be noted. For different product specifications and different contents, the controlled pressure is also different and needs to be set one by one specifically.
Plastic packaging and stretch film packaging still requires strict control of the pressure value during the temperature change process. Because there is a certain amount of air in the box, the heat transfer is relatively slow, so during the heating and cooling process, the temperature cannot change too fast, and all products placed in the sterilization retorts must be synchronized within a smaller temperature range as much as possible. The ground heats up and cools down. The purpose of this is to make the packaging material basically not subject to pressure difference, thus ensuring that the packaging material will not be deformed due to pressure during the entire sterilization process. As mentioned before, it is necessary to make all the products in the sterilization retorts synchronously heat up and cool down within a small temperature range, which places high requirements on the heat distribution performance of the sterilization retort machines.
Box packaging: The sterilization of this type of product still requires strict control of the pressure value during the temperature change process. Because there is a certain amount of air in the box, the heat transfer is relatively slow, so during the heating and cooling process, the temperature cannot change too fast, and all products placed in the sterilization autoclave must be synchronized within a smaller temperature range as much as possible. The ground heats up and cools down. The purpose of this is to make the packaging material basically not subject to pressure difference, thus ensuring that the packaging material will not be deformed due to pressure during the entire sterilization process. As mentioned before, it is necessary to make all the products in the sterilization chamber synchronously heat up and cool down within a small temperature range, which places high requirements on the heat distribution performance of the sterilization chamber.
Cup-shaped packaging and bowl-shaped packaging: The sterilization of these products still requires strict control of the pressure value during the temperature change process. Because there is a certain amount of air in the box, the heat transfer is relatively slow, so during the heating and cooling process, the temperature cannot change too fast, and all products placed in the sterilization autoclave must be synchronized within a smaller temperature range as much as possible. The ground heats up and cools down. It is worth noting that if the air content in the packaging material is small, the problem of product compression can be ignored, that is, the back pressure in the sterilization autoclave retort can be increased, so that the sterilization autoclave is always at a level during the entire sterilization process. pressure. Because the materials in the packaging materials are incompressible and have little air content, even if the external pressure is large, the packaging materials themselves will not be deformed.
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