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.