Modified Atmosphere Packaging (MAP)

Generally speaking, Modified Atmosphere Packaging (MAP) is the substitution of the atmospheric gas content inside a package by another gas mixture, O₂ being usually removed to be replaced by nitrogen or carbon dioxide.

This is achieved by “flushing” another gas mixture into the package after the food has been placed inside, which results in the atmospheric gas content being replaced. The flexible packaging is then sealed hermetically.

The purpose of this operation is to extend the shelf life of the products, mostly perishable food, by reducing ongoing biological or physiological process.

Even within the same sort of food, like fruits, for example, the maximum CO₂ tolerated can vary from 2% to 15%, depending on the kind of fruit packed. It is the responsibility of the Food Manufacturer to ensure that the correct mix of gases is selected, and that it will remain undisturbed until the last day of the shelf life.

2. Selection of adapted packaging materials: The appropriate selection of the film adapted to the application is critical. MAP plastic films can be either laminated or coextruded. For coffee application, for example, high-barrier foil-based laminate, made out of multiple layers, are perfectly suitable to prevent oxygen, moisture, light, and extreme temperatures to enter the packaging after it has been sealed hermetically. For fruits however, you have to select a “breathable” film that allows some permeability, to achieve “Equilibrium Modified Atmosphere Packaging” (EMAP). The “breathable film” is required because the fruits will continue to consume O₂ and produce CO₂ and some water vapor after having been packed, so the film will allow their transfer both ways via permeation control, and therefore maintain the integrity of the original gas mix.

3. Preventing leaks: leaks are the enemy number one of MAP packaged foods. During transportation to their retail destination, packaged food can be subject to a certain number of stresses: pressure differences, package compression, extreme temperatures leading to the escape of the gas recipe from the packaging, and its subsequent undesirable replacement by atmospheric gases like O₂. This may have consequences before the end of the shelf life of the product, like loss of taste, sogginess, mouldy appearance, change of colour, and in the worst-case scenario, food may become unsafe to consume.

All the benefits of the MAP are lost if the package leaks excessively. It is therefore absolutely necessary to ensure that the sealing has been correctly achieved to retain the gas recipe inside the packaging. However, “zero leak” does not exist. What needs to be determined is the maximum permissible leak value for your product, to ensure that it remains consumable and it retains his important characteristics like taste, crispiness and colour to maximize Customer experience, all this throughout the duration of the shelf life.

With the GammaLab, you can establish a relation between the size of the leak and the change of the O₂ content of your gas recipe in your packaging over a period of time. You can then determine your Critical Limit, and make sure that your products are within the acceptable range & that they will be correctly preserved until the last day of their shelf life.

With the GammaPro, the O₂ concentration inside the packaging of the products can be automatically measured without any human intervention, in order to compare it with the O₂ concentration that the machine is delivering. Monitoring and reporting of this value is particularly useful when production is switched during nightshift to another product with a different gas recipe for example, which allows inspection to take place the next day by the Supervisor that the gas modification was correctly executed.

Perform automatically a leak test just after, and check that the result is within expected range as per your HACCP Plan.