Modified atmosphere packaging

Modified atmosphere packaging (MAP) is an active form of packaging that involved the removal of air from the pack and its replacement with a single gas or mixture of gasses.

The gas mixture used is dependent on the type of product. The proportions of each component is fixed when the mixture is introduced. No further control is exerted over the initial composition and the gas composition is likely to change with time owing to factors such as respiration of the packed product, biochemical changes and the slow permeation of gases through the container.

Gases primarily used include oxygen, carbon dioxide, and nitrogen. Carbon monoxide has limited application in MAP, and sulphur dioxide is commonly used.

Oxygen is necessary for several processes that lead to quality degradation of the product such as fat oxidation browning and pigment oxidation. Therefore, to avoid any of these situations most of atmosphere modifications contain low concentrations or absence of oxygen.

Nitrogen is an inert gas for filling the additional scope to prevent potential collapse.

The gases used should be of a specified purity and should be selected after consideration of the potential microflora in the specific food stuff. Legally the gases are regarded as food additive.

MAP is used for fresh and heat-treated products. If the product is heat-treated, the heat treatment takes place before packaging.
Modified atmosphere packaging