ABSTRACT
Modified atmosphere packaging (MAP) is a well established technology, which in combination with proper temperature management helps in extending the shelf life and maintaining quality of perishable produce. As the technology relies on modification of package atmosphere by the respiration of the commodity and the permeability of the packaging material, the different types of polymers with a range of O2, CO2 and water vapor transmission rates have turned into the most preferred packaging material for MAP. The common plastic films used in MAP are LDPE, LLDPE, HDPE, PP, PVC, PET, PVDC, and PA (nylon). PVDC, PVC, PET and nylon have low gas permeabilities and can be used only for slow respiring commodities. However, suitable perforations in the films can expand their use to many commodities. The film properties can also be modified by combining the individual films with one another or with other materials such as paper or aluminum through processes such as coextrusion, lamination, coating and metallization. Additives as antioxidants, heat stabilizers, UV stabilizers, anti-slip agents, as well as color pigments also improve the polymer characteristics. Besides, antifogging agents, nucleating agents, antistatic agents, plasticizers, oxygen scavengers, antimicrobials are also used as additives, which have facilitated the development of active food packaging technologies. Though MAP has gained considerable acceptance, particularly for the fresh fruits and vegetables and minimally processed products, there is often a mismatch between the commodity requirements and the polymer characteristics, defeating the basic purpose of MAP, and hence, further investigation to develop polymer films of recommended gas and moisture transmission characteristics are required. Other recent research interests in MAP have been in the areas of active packaging technologies, modification of film properties by use of nanocomposites and additives, and modeling to standardize the package materials and designs for specific commodities.
