Modified atmosphere packaging is defined as ‘the packaging of a perishable product in an atmosphere that has been modified so that its composition is other than that of air’.
It is the imposition of a gas atmosphere, typically containing an inert gas, such as nitrogen combined with an anti-microbially active gas, such as carbon dioxide, upon a packaged food product to extend its shelf life.
While traditionally mainly dairy products, meat products or bread were packaged under protective atmosphere, now MAP is more and more used for other foods like fish, coffee, fruit or vegetables.
The three main gases used in MAP in Europe are O2, CO2 and N2; carbon monoxide (CO) is used widely in the United States of America (USA). All of gases are naturally present in atmosphere.
It is often desirable to generate an atmosphere low in O2 and high in CO 2 concentration to influence the metabolism of the produce being packaged, or the activity of decay-causing organisms to increase storage life.
Presence of nitrogen gas prevents the package collapse that can take place because of high concentration of carbon dioxide. In addition to atmosphere modification, MAP vastly improves moisture retention, which can have a greater influence on preserving quality.
Similar to oxygen, carbon monoxide is sometimes used to retain the red color of, primarily, meat. The required concentrations are very low. In some countries, including the EU, the use of carbon monoxide for modified atmospheres is nonetheless prohibited in foods.
MAP cannot improve the quality of a poor-quality food product. It is, therefore, essential that the food is of the highest quality prior to packing in order to optimize the benefits of modifying the pack atmosphere.
Modified atmosphere packaging
