What is Modified Atmosphere Packaging (MAP)
"Map" is a technique used to extend the shelf-life of fresh food in general, also save the flavour/aroma for some foods like coffee, spices ... etc. By changing the air surrounding the food in the package in order to reduce the activity of microorganisms, this change is made by adding either Oxygen (O2), Nitrogen (N2) or Carbon Dioxide (CO2) into the bag and then it sealed.
Also in some situations MAP Reduced the need for artificial preservatives.
Meat, fish, fruits and vegetables often use the MAP during packaging.
Equilibrium modified atmosphere packaging (EMAP) is most commonly used for cut fresh-cut produce.
The effects of each gas on food products are as follows:
Carbon dioxide (CO2)
Carbon dioxide inhibits the growth of most aerobic bacteria and moulds. Generally speaking, the higher the level of CO2, the longer the achievable shelf-life. However, CO2 is readily absorbed by fats and water – therefore, most foods will absorb CO2. Excess levels of CO2 in MAP can cause flavour tainting, drip loss and pack collapse. It is important, therefore, that a balance is struck between the commercially desirable shelf-life of a product and the degree to which any negative effects can be tolerated. When CO2 is required to control bacterial and mould growth, a minimum of 20% is recommended.
Nitrogen is an inert gas and is used to exclude air and, in particular, oxygen. It is also used as a balance gas (filler gas) to make up the difference in a gas mixture, to prevent the collapse of packs containing high-moisture and fat-containing foods, caused by the tendency of these foods to absorb carbon dioxide from the atmosphere. For modified atmosphere packaging of dried snack products 100% nitrogen is used to prevent oxidative rancidity.
Oxygen causes oxidative deterioration of foods and is required for the growth of aerobic micro-organisms.
Generally, oxygen should be excluded but there are often good reasons for it to be present in controlled quantities including:
Maintain fresh, natural colour (in red meats for example)
To maintain respiration (in fruit and vegetables)
To inhibit the growth of anaerobic organisms (in some types of fish and in vegetables).