The swelling of a bag depends on the type of packaging and the contents inside. In most cases, this bloating occurs due to product spoilage and fermentation, poor sealing, high permeability of packaging materials, temperature fluctuations, or chemical reactions that generate gas. By ensuring proper hygiene during production, using reliable sealing methods, and selecting suitable packaging materials, you can effectively prevent bag swelling.
Main Causes of Bag Swelling
1. Product Fermentation or Spoilage Produces Gas
When products containing moisture or sugar are contaminated by microorganisms, they may undergo fermentation and release gases like carbon dioxide, causing the bag to expand.
Common in: Food, ointments, cosmetics, nutritional liquids.
How to solve it:
- Maintain strict hygiene during the filling process
- Use high-temperature sterilization or aseptic filling equipment (such as LTPM liquid or paste filling machines)
- Check sealing quality to prevent air from entering
2. Poor Sealing or Air Leakage
If the sealing of the bag is not completely airtight, air will gradually enter during transportation or storage, making the bag appear swollen.
Common causes: Low sealing temperature or insufficient sealing time on automatic packaging machines.
Solutions:
- Adjust sealing temperature, pressure, and sealing time
- Clean and maintain heat-sealing molds regularly to avoid contamination that affects sealing quality
3. Packaging Material Has High Permeability
Low-cost films or single-layer plastic materials may allow oxygen and moisture to slowly enter the packaging, increasing internal air pressure.
Solutions:
- Choose high-barrier materials such as PET/AL/PE multilayer composite films
- For sensitive products, use vacuum packaging or nitrogen flushing
4. Temperature Changes Cause Gas Expansion
Residual air inside the bag expands when exposed to high temperatures. This is especially common during transportation or storage in hot environments.
Solutions:
- Avoid high-temperature storage
- Reduce residual air during packaging by using vacuum or nitrogen-filled machines
5. Chemical Reactions Generate Gas
Certain ingredients in pharmaceuticals or cosmetics can gradually react with moisture or oxygen, generating gas during storage.
Solutions:
- Adjust formulas to remove unstable components
- Use inert gas protection such as nitrogen during packaging
FAQ
Why is nitrogen used in food packaging?
Nitrogen prevents oxidation and inhibits microbial growth. It also keeps the bag slightly inflated, which is normal and does not indicate spoilage.
How to check if a bag is leaking?
Leak testing methods include the water immersion test, vacuum leak detector, or air-tightness testing equipment.
Why do some medicine packages swell?
Possible causes include moisture absorption, gas release from ingredients, or poor sealing. Packaging materials with poor barrier properties should be checked.
How can packaging machines improve sealing quality?
Use intelligent packaging machines with automatic control of sealing temperature, pressure, and time, such as LTPM CHINA pouch packaging machines or liquid filling and sealing machines.
Can high-temperature sterilization prevent swelling?
Yes. It significantly reduces gas generation caused by microorganisms, but excessive temperature or time may affect product quality.
Conclusion
Bag swelling is not a minor issue—it often indicates risks in the production or packaging process. For food, pharmaceutical, or cosmetic manufacturers, it is recommended to use automated high-precision packaging equipment, maintain a clean production environment, and perform air-tightness and stability testing before shipment.
If you are looking for a packaging solution that prevents bag swelling and improves sealing and stability, feel free to contact us. We offer a 5% discount on customized packaging machines.