Modified atmosphere packaging (MAP): how gas extends shelf life
What nitrogen, carbon dioxide and oxygen do inside the pack, typical atmospheres by product group, and what “food grade gas” actually means.
3 min read
Food spoils for three main reasons: contact with oxygen, microbial activity and moisture loss. Modified atmosphere packaging (MAP) replaces the air inside the pack with a mixture matched to the product, slowing all three at once. Shelf life increases without additives and without altering the product itself.
Three gases and their jobs inside the pack
| Gas | Food code | Role in the pack |
|---|---|---|
| Nitrogen (N₂) | E941 | Inert filler. Displaces oxygen, delays fat oxidation and stops the pack from collapsing. |
| Carbon dioxide (CO₂) | E290 | Slows bacterial and mould growth. Dissolves into the product and its water; if the ratio is wrong the pack shrinks. |
| Oxygen (O₂) | E948 | Usually unwanted, but used to keep red meat visually fresh and to reduce anaerobic risk in some products. |
You can find the data sheets in our guide: Pure Nitrogen, Pure Carbon Dioxide and the food grade Biogon mixtures — for example Biogon NC 20.
Typical atmospheres by product group
The values below are widely used starting ranges. The exact mixture is confirmed by trials, based on the fat and water content of the product, the pack-to-product volume ratio, film permeability and the target shelf life.
| Product group | Typical atmosphere | Why |
|---|---|---|
| Fresh red meat | High O₂ + CO₂ | Oxygen keeps the colour bright, carbon dioxide suppresses microbial growth |
| Poultry and fish | CO₂ dominant + N₂ | High CO₂ delays spoilage; nitrogen maintains pack volume |
| Cheese and dairy | CO₂ + N₂ | Mould growth is suppressed; CO₂ is kept low for hard cheeses |
| Bakery | CO₂ dominant or 100% CO₂ | Mould is the critical spoilage route |
| Fresh pasta and ready meals | CO₂ + N₂ | Both microbial protection and pack shape retention |
| Nuts, crisps, coffee | Mainly N₂ | Removing oxygen to delay rancidity in fats |
What does “food grade gas” mean?
A gas that is adequate for industrial use is not automatically suitable for food contact. A food grade gas is expected to meet the purity required by food additive regulation, to come with the appropriate analysis and traceability documents, and to be supplied in cylinders prepared for that purpose. In practice, watch for:
- Documented compliance with the purity required of the gas as a food additive (E941 for N₂, E290 for CO₂, E948 for O₂).
- Batch-level traceability — the first thing asked for in an audit.
- Cylinders and fittings dedicated to this purpose and never mixed with the industrial line.
- Regular verification of the mixture ratio on the line; mixer drift quietly shortens shelf life.
Common problems in practice
- Pack collapse. If CO₂ is too high for the product it dissolves into it and the pack sinks. The usual fix is to raise the nitrogen share.
- Residual oxygen. A short vacuum/gas exchange cycle leaves oxygen inside. Residual O₂ should be measured on the line.
- Film choice. A film with a poor gas barrier renders the right mixture ineffective within days.
- Product-to-pack volume ratio. Too little gas volume means short protection; a gas volume of at least twice the product volume is a common target.
- Sealing. A dirty or cold sealing jaw leaves micro-leaks, and the resulting shelf-life loss is diagnosed late.
Where to start
Share your product, your current pack and film structure, your target shelf life and your current mixture if you have one; we will determine the right food grade gas or mixture, cylinder size and supply plan together. Start by reviewing our food gases family.
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