Packaging gases

Modified Atmosphere Packing (MAP)

Packing foodstuffs in a gas atmosphere results in a prolonged shelf life of the foodstuffs and at the same time the food quality is retained.

The appearance of the food that is packed, is mainly determined by the mixing proportion between carbon dioxide and nitrogen. If the entire process is seen from the point of view of desired shelf life, it is more acceptable to pack with a high concentration of carbon dioxide. As carbon dioxide dissolves in the water phase of the product, the pack will look as if it has been vacuum packed, i.e. the pack will contract. To avoid this, nitrogen is added to the mixture as this prevents such a contraction occurring. The most usual proportions are 70:30 or 60:40.

Even though nitrogen is used mainly as a filler gas, this gas can be used alone in the packaging and improved product shelf life is attained.

Carbon dioxide 

Carbon dioxide is the most important gas for packing as it inhibits the development of bacteria and mould. To achieve this effect, the concentration of Carbon Dioxide in the pack must be more than 25% at the time of packing.

Nitrogen

Nitrogen is mainly used to expel oxygen, and it can be regarded as a filler gas in the pack. Nitrogen has no direct effect on microbiological storage qualities or colour.