Vacuum Packaging Conditions for Granular Materials
1. Material Selection
The packaging film must have excellent barrier properties to block oxygen and moisture. Common choices include multi-layer films like PET/AL/PE (polyester/aluminum/polyethylene) or EVOH (ethylene vinyl alcohol) for enhanced protection. The thickness and durability of the film should also match the product's abrasiveness-coarser granules may require stronger materials to avoid punctures.
2. Moisture & Oxygen Control
Granular materials should be pre-dried to a moisture content below 5% to prevent condensation inside the package. For oxygen-sensitive products (e.g., coffee, nuts), adding oxygen absorbers or nitrogen flushing can further prolong freshness.
3. Particle Size & Shape Considerations
Fine powders (e.g., flour, spices) require gentler vacuum settings to prevent dust dispersion, while larger granules (e.g., rice, beans) can withstand stronger suction. Irregularly shaped particles may need vibration-assisted settling to ensure even distribution before sealing.
4. Packaging Equipment & Settings
- Vacuum Level: Typically set between 0.08–0.1 MPa, adjusted based on material density.
- Sealing Temperature: Ranges from 150–200°C, depending on film type.
- Machine Type: Vertical form-fill-seal (VFFS) machines are ideal for automated packaging, while chamber vacuum sealers work well for smaller batches.
5. Sealing Integrity & Quality Checks
- A strong, wrinkle-free seal is crucial to prevent leaks. Common tests include:
- Pressure decay testing to detect leaks.
- Visual inspection for proper sealing and film integrity.
6. Storage & Handling
Even with optimal packaging, storage conditions matter. Vacuum-sealed granular products should be kept in cool, dry environments to avoid temperature fluctuations that could cause condensation.
