Modified atmosphere packaging (MAP) of fresh produce relies on the modification of atmosphere inside the package achieved by the natural interplay between two processes: the respiration rates of the commodity and the permeability of the packaging films. MAP has been a proven technology to meet the consumer's demand for more natural and fresh foods, which is increasing day by day. Because of its dynamic phenomenon, respiration and permeation take place simultaneously, and it is necessary to design the MAP system and select the matching films to achieve desired atmosphere early and maintain as long as possible. To meet the desired film characteristics for MAP, the different plastic films are either laminated or coextruded. In this modern world, the packaging films of required gas transmission properties are made available through advanced technology. Although the MAP industry has an increasing choice of packaging films, most packs are still constructed from four basic sustainable polymers: polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyproylene (PP) and polyethylene (PE) for packaging of fresh produce. Polystyrene has also been used but polyvinylidene, polyester and nylon have such low gas permeabilities that they would be suitable only for commodities with very low respiration rates.

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Modified atmosphere packaging (MAP) is a dynamic system during which respiration and permeation occur simultaneously. Hence factors affecting both respiration and permeation were considered for designing a package. In the design of MA packages for guava (cv. Baruipur) a total of 13 variables were considered. The independent variables includes: weight of fruits, surface area of packaging film, free volume of the package, thickness of the film and permeabilities of film to O 2 and CO 2 gas. The fixed variables considered were: the surrounding gas composition and temperature, the respiration rates for O 2 consumption and CO 2 evolution, and the equilibrium gas compositions to be attained in the package so that the fruit's shelf-life is extended. Two types of MA packages, having package size of 19 cm× 19 cm for a fill weight of 1,000±100 g were developed. Packages were designed to accommodate a fill weight range of 0.90-1.10 kg. Various package parameters were optimized to facilitate establishment of dynamic equilibrium at target levels of O 2 and CO 2 concentration in the package. The storage study of MA packages was performed at 10, 15, 20 and 25°C temperatures. The performance of film packages was evaluated for their ability to establish equilibrium at target levels and to extend the shelf life of the packaged fruit. The MA packaging system increased the shelf life of guava by 128-200 % compared to the unpacked fruits at various storage temperatures with a quality comparable with the freshly harvested commodity.