Gas packaging

Packaging foods in atmospheres containing an inert gas and carbon dioxide inhibits both oxidative reactions and microbial spoilage. The use of a inert gas for coffee packaging for example increases shelf life three-fold with respect to vacuum packaging.

Oxidation of foods is largely chemical process driven by oxygen, which can be blocked by the displacement of oxygen by nitrogen.

The gas packaging technique involves packaging of product in an impermeable film with the appropriate gases and heat sealing of packages.

The gases commonly used for gas packaging of bakery products are N2 and CO2, These are neither toxic or dangerous nor are they regarded as food additives.

Other gases which have antimicrobial properties include carbon monoxide, sulphur dioxide ethylene oxide, ozone, nitrous and nitric oxide.

In inert gas packaging the air inside the container is replaced by inert gas either through the compensated vacuum technique or by flushing the inside of the package with inert gas.

In the former case, first a vacuum is created in the package, then enough inert gas to balance the internal and external pressure is admitted. In the latter case, a drop of liquefied inert gas is placed in the bottom of the package, which evaporates pushing the air out.

MAP gases can be delivered either as pre-mixtures in cylinders or as bulk gases to be mixed on site. Bulk gases may be delivered as compressed gases in cylinders or as cryogenic liquids.
Gas packaging

Inert gas for food packaging

It has been known for many years that altering the composition of the atmosphere surrounding a food can result in useful increases in shelf –life. Some gases, such as nitrogen and argon, are inert and therefore show no inherent antimicrobial activity.

In inert gas packaging the air inside the container is replaced by inert gas either through the compensated vacuum technique or by flushing the inside of the package with inert gas.

For example, the shelf life of roasted coffee could be improved by replacing the air inside the package with an inert gas such as N2 or Co2. Although the latter is not an ‘inert’ gas, it is naturally present in the product.

The procedure applied is based in the initial application of vacuum followed by its release with the desired gases. The pressure in the package is in equilibrium with the atmosphere at the moment of sealing. Just like in air packaging, to prevent internal pressure rising due to degassing, coffee must be either packed after degassing or the package fitted with a one-way valve.

Inert gases restrict the growth of aerobic organisms, like mounds, by reducing the amount of oxygen present. To be effective, at least 98% of the inert gas needs to be present in the headspace atmosphere, and this must be maintained during storage.

From a legal standpoint the gas added to the package is considered a processing aid rather than an additive, since it dissipates on opening.
Inert gas for food packaging