There are not many new technologies in food preservation. One of the newest options, although it has been around in rudimentary form since the early part of the 1930s, is the use of modified atmosphere packaging or MAP.
The original use of controlled environments in the early days was in cargo ships transporting fruit. Carbon dioxide was pumped into the holding areas for the fruit, slowing down the ripening process for the sea voyage from producing country to consumer. Later, specific packaging processes were used to create MAP and more recently to further refine this to EMAP.
EMAP is equilibrium modified atmosphere packaging, and it actually goes back to the original increase in carbon dioxide in packaging to prevent ripening and spoiling of fresh fruits and vegetables. Keep in mind that fruits and vegetables can be harder to maintain due to the gasses they produce during the natural ripening process.
MAP Considerations
Many different types of food items can be preserved or have a significant extension to their shelf life through the use of MAP. Meats, fish and cheese will have different requirements for the specific gas mixture used in the packaging process as well as the type of film used. Some films are more or less permeable, which will enhance the preservation of the food item while also providing high levels of visibility and appeal for marketing and consumer appeal.
Safety Considerations
With a single product packaging requirement, such a sliced cheese or a cut of meat, it is less complicated to determine the correct gas mixture and film type for the modified atmosphere packaging.
Mixed types of foods, such as cooked entries, can be more of a challenge. Packaging will need to take into consideration the moisture levels, the composition of the food as well as the type of bacteria that may be problematic. Each bacterial strain responds differently to levels of nitrogen, oxygen and carbon dioxide, so both the original flushing gas as well as the final gas mix have to contain the right mixture to inhibit rather than enhance bacterial growth while also preserving the product.
Finally, it will also be critical to ensure that the film has the oxygen transmission rate or OTR that matches the respiration rate of the product. With most fruit and vegetables the process of cutting and packaging will increase the respiration, which will lead to browning on the produce as well as more microbial growth if the OTR is not correct.
There are ongoing tests and studies through the US Food and Drug Administration to provide clear guidelines for the correct application of MAP in safe food storage. Packaging equipment producers incorporate these recommendations into their equipment designs, helping producers to limit safety factors in MAP.
