The shelf life of most foods can be extended with modified atmosphere packaging (MAP ), a practice that more than 30 years ago is being implemented progressively in the food industry. In this technique the atmosphere between the container and food is different from the air, but should be compared with storage in controlled atmosphere where the product is constantly exposed to a well-defined gas mixture. MAP can be defined as food packaging material impervious to gases, whose indoor environment has been modified to reduce the processes of respiration, reduce the growth of microorganisms and retard the enzymatic alterations, which is able to extend the life of the product when combined with proper cooling.
gases normally used in MAP are carbon dioxide (CO2), oxygen (O2) and nitrogen (N2).
The CO2 is used because at high concentrations inhibits the growth of most microorganisms responsible for the alteration of food. However the drawback that some psychrophilic pathogenic microorganisms, ClostridiumBotulinum as they can grow in these conditions and create toxins before it is observable alteration in the food.
The N2 is an inert gas, with little antibacterial properties but has the advantage over CO2 disseminated not in food, which does make the CO2. CO2 is normally combined with antibacterial properties to its characteristic N2 inert gas.
The O2 is necessary in some cases, as in the packaging of raw meat to maintain its bright red color through the oxygenated form of myoglobin. The thickness of the oxymyoglobin layer depends on the partial pressure of O2, but at higher pressure decreases the life of the product by encouraging the growth of bacteria responsible for the alteration.
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