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The Influence of Treatment and Storage Conditions on Gas Permeability through Polymeric Packaging Materials

One of the most important characteristics of polymeric material used for food packaging is gas permeability. Polymeric materials have different permeability characteristics depending on its thickness, temperature, permeate characteristics (shape and size), pressure differences, additive presence, molecular structure of polymers etc. The resistance of polymeric materials towards chemical nature of the foodstuffs is also important. For this purpose model solution, as food simulants in contact with polymeric materials are often used at specific test condition. The permeation of oxygen and carbon dioxide through polypropylene monofilm and polyethylene/polyester laminate is studied. Permeability characteristics of materials is analysed before and after fresh shredded cabbage packaging, as well as after additional treatment with acetic acid solution. Measurements are performed at 20 oC, 40 oC and 60°C. Low permeability values are obtained for untreated samples. Treated samples showed higher permeability values which increases with increasing temperature. The exception is noticed in the case of laminate PE/polyester, showing the lowest permeability at higher temperature. Activation energy for permeation is in a good accordance with Arrhenius equation. Very low global migration values are determined. The obtained values are much lower than the maximum permitted global migration, set by EU directives, for the polymeric materials when in contact with food simulants.

carbon dioxide; oxygen; permeability; polypropylene; polyethylene/polyester laminate; storage.

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