Food & deli
How does modified atmosphere packaging (MAP) work?
Short answer
In MAP, the air in a food pack is replaced with a protective gas mix before the pack is sealed with a barrier film. Carbon dioxide slows bacteria and mould, nitrogen fills the space so the pack does not collapse, and for red meat oxygen keeps the colour. The tray and lid must block gas, which is why MAP uses barrier trays such as AVI's RTE 104 140/40 and TBT 140 190/50 PP with barrier lidding.
Part of the guide: Meat, poultry and seafood packaging guide
- Main gasesCarbon dioxide, nitrogen, oxygen
- NeedsBarrier tray, barrier lid, sealer with gas flush
AVI's MAP trays
| Pack | Type | Size (L × W × H) | Empty weight | Holds | Per carton | Enquiry |
|---|---|---|---|---|---|---|
| RTE 104 140/40 | Modified-atmosphere-packaging tray | 140 × 104 × 42 mm | 10 g | — | — | |
| RTE 104 140/40 2CP | Modified-atmosphere-packaging tray | 140 × 104 × 42 mm | 10 g | — | — | |
| TBT 140 190/40 PP | Modified-atmosphere-packaging tray | 190 × 140 × 40 mm | 18.3 g | — | — | |
| TBT 140 190/50 PP | Modified-atmosphere-packaging tray | 190 × 140 × 50 mm | 20 g | — | — | |
| RTE 140 190/40 3CP PP | Modified-atmosphere-packaging tray | 190 × 140 × 40 mm | 18.8 g | — | — | |
| RTE 200 310/45 PL PP | Modified-atmosphere-packaging tray | 310 × 200 × 45 mm | 33 g | — | — |
All packs are rPET. Figures from AVI's catalogue; tolerances and fill depend on the produce, so samples are the final check.
AVI products for this
- MAP / Modified Atmosphere Trays13 MAP tray formats from AVI Global Plast, matched to AVI's high-barrier film structures for extended shelf life....
- High Barrier Films for Thermoforming & Food PackagingAVI Global Plast's high barrier films — PET/PE, PET/EVOH/PE and PET/PA/PE structures, 100–800 microns, for MAP,...
The gases and what they do
| Gas | Role |
|---|---|
| Carbon dioxide (CO₂) | Slows the growth of bacteria and mould |
| Nitrogen (N₂) | Inert filler; stops the pack collapsing as CO₂ dissolves into the food |
| Oxygen (O₂) | Keeps red meat red; left out for most other foods |
Typical mixes: red meat is often packed high in oxygen (around 70% O₂ with 30% CO₂); poultry, fish and cheese use CO₂ with nitrogen.
Fresh produce is different
Fruit and vegetables keep breathing after harvest, so they are not sealed in a fixed gas. Instead, a film with the right permeability (or micro-perforations) lets the pack settle at low oxygen and raised CO₂ on its own, which slows ripening.
What the pack needs
- A tray with a flat sealing flange and enough barrier for the shelf life.
- A barrier lidding film matched to the tray.
- A tray sealer that flushes the gas and seals in one step.
- For meat, often an absorbent pad or capillary tray to hold drip.
Related questions
What is the difference between MAP and vacuum packing?
Vacuum packing removes the air and pulls the film tight onto the food; MAP replaces the air with a gas mix and leaves the food loose in the tray. Both need barrier materials.
What are the disadvantages of MAP?
It needs barrier materials, a sealing machine with gas flushing and a gas mix chosen for each product, and the benefit ends once the pack is opened. Multi-layer barrier packs are also harder to recycle than single-material ones.
Is MAP safe?
Yes. The gases are those already in air, used in different proportions; MAP is widely used for meat, fish, cheese, salads and bakery.