In the process of high temperature sterilization, the residual gas in the retort bag expands and the volume of contents becomes larger, which makes the pressure inside the bag rise. When the pressure inside the bag is greater than the internal pressure the bag can bear, the bag will be burst.In order to ensure that the retort bag does not break during the sterilization process, professional packaging manufacturers Lucky time pack give you some tips.
Use pressure sterilization and pressure cooling
After the retort bag enters the sterilization pot, it depends on the initial temperature of the retort pouch , the amount of bag, the amount of residual air, to determine how hot the pot is before air pressure is applied. Generally, the pressure starts from 90 degrees.If the pressurization starts too early, the heating time is extended, and if the pressurization starts too late, it is easy to break the bag.
The choice of sterilization medium during sterilization is also related to whether the bag is broken. General sterilization media include three types of high-pressure hot water, high-pressure steam, and steam + air mixed gas, each of which has its own advantages.
Studies have shown that high-pressure hot water is heated more evenly than the latter two during sterilization, but its disadvantage is that it consumes more heat when it is heated, and sometimes it will deform the packaging bag or contaminate the product. The other two have almost no such shortcomings. In other words, the steam + air mixed medium seems to be the most ideal, but the ratio of the air should be appropriate. If the air is too much, the heat transfer performance of the container is poor and the sterilization effect is reduced. On the contrary, if it is too little, the retort pouch may be broken by a slight change in pressure.
Inspection of packaging strength
It mainly includes the detection of sealing strength, peel strength, pressure strength, static pressure strength, puncture strength and drop strength.
The sealing strength reflects the firmness of the hot-melt sealing part of the retort bag. The peeling strength (or composite strength) reflects the reliability of the compounding between the layers of the retort bag. The internal pressure strength (burst strength) reflects the ability to withstand the pressure inside the bag. Compressive strength (external pressure strength) reflects the strength of the external static pressure that the retort bag filled with the content can withstand. The puncture strength reflects the strength of the retort bag under the pressure of the sharp object. The drop strength reflects the drop height allowed during the loading and unloading process after the retort bag filled with the contents is sealed.
In order to ensure the sealing strength, the key is not to contaminate the sealing part of the retort bag when filling the product. If juice, water droplets, etc. adhere to the inside of the sealing part, the sealing part area cannot be sealed.
The flatness of sealing position of the packaging bag is also one of the factors that affect the quality of the seal. To keep the sealing of the bag flat, no wrinkles occur after sealing, and the following points should be paid attention to: The mouth of the retort bag must be flat and the two sides have the same length, the sealing die of the sealing machine is flat on both sides and kept parallel, and the fixture is good, the content should not be too large, the amount should not be too much, and the total thickness of the bag should not exceed the limit requirements.
Pay attention to the sealing temperature and pressure. The retort time depends on the material of theretort bag, the melting temperature of the film, and the thickness of the edge seal. Within a certain sealing time, too low temperature will cause incomplete melting, and if the temperature is too high, it will cause the film to melt too much and change its physical and chemical properties.