When exposed to oxygen, foodstuffs degrade rapidly. Protective atmosphere packaging helps to overcome this problem. Here is an overview of this packaging method, which is also called MAP (Modified Atmosphere Packaging).

Replace air with other gases

The packaging under protective atmosphere consists in protecting the food from any contact with the air by replacing it by other gases, of industrial origin. In practice, this technique is often combined with low temperature preservation.

In general, the industrial gas used is a mixture, adapted to the type of food to protect. The different gases authorized for modified atmosphere packaging are listed in the European Directive 2008/84/EC:

- Nitrogen (N2) prevents pigment oxidation and bacterial proliferation.
- Carbon dioxide (CO2) limits the growth of bacteria and molds.
- Oxygen (O2) preserves the color of the meat and prevents the proliferation of germs.
- Argon (Ar) acts like nitrogen, while reducing enzymatic decomposition.

Nitrogen promotes the preservation of dry products, while oxygen protects fresh fruits and vegetables, meats and fish. Argon is used to package vulnerable products such as wine. The gases used can be produced on the user's site using a specific generator (nitrogen generator, oxygen generator...), possibly coupled with a mixer.

Optimal food preservation

Protective atmosphere packaging offers many advantages for the preservation of foodstuffs:

• It prolongs their freshness
• It  moves back the shelf life
• It facilitates inventory management across the distribution chain
• It guarantees hygiene by reducing the risk of bacterial contamination
• It allows a better presentation of products, more attractive for the consumer

This mode of conditioning, on the other hand, requires a strict respect of the cold chain, and is not suitable for all types of food.

The packaging process

The protective atmosphere packaging has several stages.

It starts with the choice of the packaging itself, which must be adapted to the foodstuffs to be protected. Some foods require permeable films, which allows them to breathe. This is the case of fresh fruits and vegetables. Others, on the contrary, must be wrapped in totally hermetic films. This is the case with meat and fish.

The preservative gas is then injected into the package. For this, two techniques are possible:

● gas scavenging: it consists in injecting gas into the packaging until it has replaced the air.

● the compensated vacuum: it consists in removing the air from the packaging before injecting the gas.

Gaseous sweep is suitable for fragile foods. The compensated vacuum is better suited for products able to withstand the pressure generated by vacuum.

Finally, once packaged, the food is carefully controlled. Various techniques make it possible to perform this control : the tightness of the packaging can be tested by using vacuum measurement instruments, or the gas contained in the package can be analyzed.