Packaging technology for improving shelf-life of fruits based on a nanoporous-crystalline polymer

The ability of films with an active layer of nanoporous–crystalline syndiotactic polystyrene (s-PS) to prolong shelf-life, not only of climacteric but also of non-climacteric fruits, is discussed. Studies on oxygen and carbon dioxide concentrations in the environment of packaged fruits as well as in s-PS active layers have been combined. Reported results indicate that prolonged shelf-life can be associated with large increases and decreases of carbon dioxide and oxygen concentrations inside the package, respectively. These data are consistent with a higher barrier offered to both gases by nanoporous–crystalline s-PS layers. This barrier phenomenon is due to reduction of gas diffusivity typical of nanoporous–crystalline polymer films, which is further enhanced by orientation, parallel to the film plane, of crystalline planes of closely packed s-PS helices.