**4.1 Modified atmosphere packaging (MAP)**

Polymeric films are regularly used because of their advantages and their availability, the chief factor in their control of movement and concentration of gasses by lowering the oxygen concentration and raising carbon dioxide concentration that abridges the respiration rate and promotes produce shelf-life (controlled atmospheric (CA) packing). Temperature control plays a crucial role in modified atmosphere packaging (MAP) packing as it directly influences respiration rate that shows an effect on the shelf life of produce. The major drawback of MAP packing is that the concentration of O2 is reduced to a greater extent that may result in the fermentation of tissues producing undesirable off-flavors.

MAP can be done in 2 ways:


However, the packing material used may not satisfy all the properties required, so they are combined to provide a wide range of characters by lamination and co-extrusion. The concentration of gasses accumulated depends on many variables


#### *Advances in Postharvest Packaging Systems of Fruits and Vegetable DOI: http://dx.doi.org/10.5772/intechopen.101124*

#### **Table 1.**

*Gas permeability and water transmission rate (WTR) of polymeric film available for packaging of MAP produce.*


#### **Table 2.**

*Recommended gas mixtures for MAP.*

such as the chemical composition of products, packing material permeability, product respiration, and the influence of temperature on them. A lot of commercial interest has been focused on developing packing materials with high gas transmission rates. For major polythene films have more permeability to CO2 than O2, thus aid in maintaining a proper gaseous ratio. Thus, packaging film of the correct permeability must be chosen to realize the full benefits of MAP of fresh produce [17].

Typical packing material should have a 2–10% O2/CO2 ratio to maintain the freshness of produce and enhance its shelf life. Highly respiring produce must not be loaded in traditional packing material such as poly(vinyl chloride) (PVC), low-density polythene (PE-LD), polypropylene, oriented (OPP), instead kept in the highly permeable micro-perforated film so that the gaseous concentration is maintained. Ceramic films have high oxygen, carbon dioxide, ethylene permeability [18]. Films that have high gas permeability are usually a mixture of two or more non-numeric units each contributing a specific character such as strength, transmission, durability, permeability, etc. Furthermore, films can be laminated to achieve desired traits Films using micro-perforations can attain very high rates of gas transmission [19]. Films with micro-perforations are preferred, generally, the size ranges from 40 to 200 μm, and by making modifications to them we can regulate the gaseous concentration to meet product requirements. Based on the release of gasses from perforations of film, suitable packing materials have been identified for mushrooms. Perforated packing materials also proved good to store nectarines, apples, asparagus, etc. Macro perforated material can also be used to pack some strawberries and raspberries. Micro-perforated material is expensive and may also allow entry of some pathogens during wet handling conditions [17].

The most effective and efficient way for packing high respiring produce is by combining high O2 MAP and low O2 MAP, because of high oxygen concentration there is the prevention of off-flavors and odd odors that result due to fermentation [11, 17]. Macro perforated material can also be used to pack some strawberries and raspberries. Micro-perforated material is expensive and may also allow entry of some pathogens during wet handling conditions [17].

The most effective and efficient way for packing high respiring produce is by combining high O2 MAP and low O2 MAP, because of high oxygen concentration there is the prevention of off-flavors and odd odors that result due to fermentation [11, 17].


*Advances in Postharvest Packaging Systems of Fruits and Vegetable DOI: http://dx.doi.org/10.5772/intechopen.101124*

