The principle behind vacuum bags is based on the physical mechanism of reducing air inside the bag to lower the oxygen content, thereby extending the shelf life of food. The following is a detailed explanation:
1. Vacuuming Principle
Vacuuming involves using a vacuum device (such as a vacuum pump) to extract the air from the bag, lowering the air pressure inside the bag to below the external pressure, creating a near-vacuum sealed environment.
The process is as follows:Place the item: Place the food or other item into the vacuum bag;
Evacuation and Sealing: After the vacuum pump is activated, the connected pump begins to extract the air from the bag;
The air inside the bag gradually decreases, creating a negative pressure;
After the air is extracted, the vacuum pump immediately seals the bag, heating the bag opening to prevent further air from entering.
The vacuum environment is established: The bag adheres tightly to the surface of the item, inhibiting microbial growth.
This prevents oxidation, moisture, and mildew, thereby extending the shelf life.
2. Why Does Vacuuming Preserve Food?
Microbial Inhibition: Many aerobic microorganisms, such as bacteria and mold, cannot survive in oxygen-free or low-oxygen environments.
Reduce Oxidation: Oils, fats, and iron-containing foods are susceptible to spoilage in high-oxygen environments; vacuum packaging can prevent oxidation.
Prevent Moisture Loss: Vacuuming reduces air contact, preventing moisture evaporation from food.
Inhibit Odor Transfer: Prevents food from absorbing refrigerator odors or transferring flavors.
3. Vacuum Bag Compatibility Requirements
Strong Airtightness: The bag must have excellent barrier properties to prevent air permeation.
Pressure and Tension Resistance: After vacuuming, the bag will fit tightly to the item, without cracking or leaking.
Secure Sealing: The heat seal must be secure and must not be loose, otherwise it will affect the freshness preservation effect.
Suitable Materials: Common materials such as PA/PE, PET/CPP, and PA+PE co-extruded films.
