MAP is modified atmosphere packaging in which you change the composition of gas in a container with a fixed gas mixture. After doing so you do not have any control over the process and the gas composition changes inevitably in the container due to activities such as product respiration. On the other hand in Controlled Atmosphere Packaging (CAP) you have control over the storage atmosphere (which is in fact air tight). As the desired gas composition (i.e. high carbon dioxide level and low oxygen level) changes due to metabolic activity of fruits and vegetables, it is possible to add fresh air or nitrogen to achieve pre-determined (desired) gaseous composition.
MAP is modified atmosphere packaging in which you change the composition of gas in a container with a fixed gas mixture. After doing so you do not have any control over the process and the gas composition changes inevitably in the container due to activities such as product respiration. On the other hand in Controlled Atmosphere Packaging (CAP) you have control over the storage atmosphere (which is in fact air tight). As the desired gas composition (i.e. high carbon dioxide level and low oxygen level) changes due to metabolic activity of fruits and vegetables, it is possible to add fresh air or nitrogen to achieve pre-determined (desired) gaseous composition.
I broadly agree and I think there is an element of control with MAP. You may for example use a micro-perforated film to generate a specific and controlled gas composition over shelf-life. You may do real time micro-perforation to match respiration rates of produce as it changes with the season. You also exert control by the selection of materials with appropriate barrier properties.
In MAP you can modify the atmosphere and changes the gas composition inside at the packaging moment (addition of CO2, and other gases). It is generally in order to keep oxygen content low. In CAP you don't modify the gas composition directly, but using proper films or coatings you change the gas exchanges that normally occur due to respiration inside the bag. For example it is common the use of film that reduce the loss of CO2 from the bag while they accellerate the release of O2 from the bag once produced by respiratory processes.
In MAP once you fixed the gas composition the it is left in packing without monitoring the individual gad (O2 CO2 and N2) but CAP specific film or sachet within the pack, cork with gas scavenger or scrubber are used to control the O2 and CO2 level and also ethylene level within the pack.
Basically, there are two types of MAP; passive MAP and active MAP. The former is basically the modification of air inside the package which relies on an interplay between the packaged produce respiration process and the permeability of the packaging material. Here, I would like to emphasize on the importance of careful selection of packaging film/material that matches the respiration rate of the produce in order to generate an effective equilibrium MAP (EMAP). On the other hand, in active MAP, the in-package gas composition is modified actively by replacing normal air (mainly 78% N2, 21% O2 and 0.035% CO2) with a desired mixture of gases. However, in spite of the initial introduction of gas mixture in the active MAP headspace, the maintenance of final EMAP ultimately depends on film permeability and produce respiratory characteristics.
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