How high-temperature retort pouches adapt to the requirements of content packaging and sterilization processes

Retort pouches must withstand the packaging process of the contents and subsequent sterilization process, so this condition has a great impact on them. The finished product after final packaging and sterilization must have a flat surface, and the packaging material itself must be free of shrinkage, wrinkles, bubbles, delamination, leakage, etc. The following are the key points to note:

        1 Select appropriate materials and structures according to the shape and properties of the contents. For example, different material structures should be selected for solid, liquid, or solid-liquid mixed states. Meat products with bones or thorns cannot pierce the bag before and after high-temperature sterilization. If the acidity and alkalinity of the contents are different, the material structure and specifications of the bag should be adjusted accordingly.

        2 Before mass use of retort pouches, food enterprises should confirm the performance of retort pouches through simulation tests. Due to the influence of the physicochemical properties of the contents, changes may occur at high temperatures, producing new substances that may penetrate between the layers of the retort pouch, thus reducing the packaging performance of the retort pouch.

        3 Select an appropriate packaging sealing temperature to ensure that the seal is firm, preventing leakage during sterilization and preventing bacteria in the cooling water from entering and contaminating during cooling.

        4 If it is not vacuum packaging, pay attention to controlling the amount of residual gas in the package, making the proportion moderate and the residual amount basically consistent. Otherwise, even if there is back pressure during the sterilization process, bags with a large amount of residual gas will burst.

        5 Determine stable high-temperature sterilization process conditions, such as standard sterilization conditions of 121 ℃ for 40 minutes Various materials used to make retort pouches have reached their maximum tolerance at 121 ℃. If the temperature and time exceed this process condition, it is difficult to ensure that certain properties of the retort pouch are not damaged, such as discoloration of light-colored ink, serious reduction in composite strength, and reduced heat sealing strength.

        6 Pay attention to the impact of material changes on the packaging, such as RCPP after sterilization hardening, leaching of additives in the material, etc. Evaluate the impact of changes in physical properties before and after sterilization, and also pay attention to the impact on the hygiene of the contents.

        7 Prevent breakage and leakage during storage and transportation, especially for vacuum retort pouches. Generally, RCPP after sterilization will harden, and leakage is prone to occur at the creases of vacuum packaging. This needs to be solved from material selection and process.

        8 Products packaged in retort pouches should not be handled roughly during handling and loading and unloading. They should be stored in a clean, dry, ventilated, and cool place, and should not be placed too close to heat sources. This can ensure the stability of the physical and chemical properties of the packaging bag and contents as much as possible. Products found to be swollen or leaking during storage and sales are prohibited from being sold or consumed. If many adverse conditions occur in the sales process, it will seriously affect the image of the product and may even destroy a brand. Enterprises using retort pouches should make a full assessment.

        9 For the contents and bags after high-temperature sterilization, a reasonable shelf life should be determined. For example, cooked meat products are rich in protein, and microorganisms are very easy to reproduce. Moreover, the fat in meat products is easily oxidized and deteriorated during storage. The shelf life is generally within one year, even with AL film structure should not exceed 24 months. Moreover, during high-temperature sterilization, some additives in the packaging material will accelerate their release to the surface under high-temperature conditions. For example, opening agents, antistatic agents, and smoothing agents added to plastic films will slowly seep out, and there is a risk of slowly contaminating food. Plastic products will also gradually age and continuously affect the performance of the bag, so they should not be stored for a long time.

        Although theoretically, according to the structure of the composite material, the shelf life of the contents can be calculated based on its moisture permeability, oxygen permeability data, and aging time, and the theoretical shelf life can be two years or even more than five years, but there are too many uncertain factors in practical applications. Considering the characteristics of the composite material itself and the uncertainty of the properties of the contents, the shelf life cannot be determined solely based on the moisture permeability, oxygen permeability data, and sealing performance of the packaging material. Therefore, it is not supported by factual evidence to determine a shelf life of more than two years for high-temperature sterilized food.

        10 Do not ignore special requirements, such as 500ml The customer standard requirements for high-temperature sterilization infusion bags with bellows seals above must meet the condition of no bag breakage after a 1.8m high natural drop. In this case, national standards cannot be blindly applied. Only by increasing the material thickness or adding anti-breakage additives to the heat-sealing layer can such requirements be met.

        The above analysis discusses the issues that need to be paid attention to in the production and use of retort pouches. Unlike ordinary bags, retort pouches must not only meet the standards before sterilization, but also meet the requirements of appearance, function, and hygiene after sterilization and within the shelf life. This actual requirement may be far higher than a certain national standard for retort pouches.

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